1
|
Yamaguchi R, Yagi Y, Okuwaki R, Enescu B. The complex rupture evolution of the long and slow, tsunamigenic 2021 South Sandwich Islands earthquake. Sci Rep 2025; 15:17706. [PMID: 40399352 PMCID: PMC12095499 DOI: 10.1038/s41598-025-02043-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2025] [Accepted: 05/11/2025] [Indexed: 05/23/2025] Open
Abstract
On August 21, 2021, a large earthquake occurred in the South Sandwich subduction zone, and the associated tsunami was widely observed. To robustly analyse the detailed seismic source process of this long-source duration (over 200 s) event occurring in a convexly shaped subduction zone, we applied the Potency Density Tensor Inversion with a non-rectangular and non-planar source surface to the broadband teleseismic P-waves. This method allows us to suitably reduce the effect of the time-increasing uncertainty of the Green's function and the effect of modelling errors related to the fault geometry. We found the slip vectors of the 400 km long rupture area rotate clockwise to the south, corresponding to the clockwise rotation of the trench strike. Our results reveal that the rupture propagated up-dip to the shallow region, then propagated to the south-southeast along the trench, and stagnated for about 30 s at around 130 km south-southeast from the epicentre. After the stagnation of the rupture front, the moment-rate gradually increased with time, although a clear rupture area could not be identified for about 45 s. Afterwards the rupture re-propagated south-southwest along the trench from the stagnation area. The slow rupture growth following the stagnation of the fast rupture triggered a new fast rupture, which led to the 2021 South Sandwich Islands earthquake having the typical characteristics of a tsunami earthquake, with a long rupture duration and a slow average rupture front velocity.
Collapse
Affiliation(s)
- Ryo Yamaguchi
- Graduate School of Science and Technology, University of Tsukuba, Tennodai 1-1-1, Tsukuba, 305-8572, Ibaraki, Japan.
| | - Yuji Yagi
- Institute of Life and Environmental Sciences, University of Tsukuba, Tennodai 1-1-1, Tsukuba, 305-8572, Ibaraki, Japan.
| | - Ryo Okuwaki
- Institute of Life and Environmental Sciences, University of Tsukuba, Tennodai 1-1-1, Tsukuba, 305-8572, Ibaraki, Japan
| | - Bogdan Enescu
- Department of Geophysics, Graduate School of Science, Kyoto University, Kitashirakawa, Oiwake-cho, Sakyo-ku, Kyoto, 606-8502, Japan
- National Institute for Earth Physics, Calugareni str. 12, P.O. Box MG-2, Magurele-Bucharest, Ilfov, 077125, Romania
| |
Collapse
|
2
|
Zheng J, Zhang Z, Li X. Relationship Between the 2019 Ridgecrest, California, MW7.1 Earthquake and Its MW6.4 Foreshock Sequence. ENTROPY (BASEL, SWITZERLAND) 2024; 27:16. [PMID: 39851636 PMCID: PMC11765204 DOI: 10.3390/e27010016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2024] [Revised: 12/16/2024] [Accepted: 12/23/2024] [Indexed: 01/26/2025]
Abstract
The 2019 Ridgecrest MW7.1 earthquake has received significant attention due to its complex fault activity. It is also noticeable for its MW6.4 foreshock sequence. There are intricate dynamic relationships between earthquakes in such vigorous sequences. Based on the relocated catalogue, we adopt the nearest neighbour algorithm to analyze its foreshock and aftershock sequences. Detailed links and family structures of the sequence are obtained. The results show that a MW5.0 event at 03:16 (UTC) on 6 July is a direct foreshock of the MW7.1 mainshock. It is likely related to barriers on the northwest-striking fault. The MW6.4 event on 4 July is characterized as a complex conjugate rupture. Notably, a magnitude 4.0 event occurred on the northwest-striking fault before the MW6.4 event, establishing it as a direct foreshock. The Ridgecrest sequence is predominantly influenced by northwest fault activity. It first caused small fractures on the northwest-striking fault. Then, it triggered conjugate slips on the southwest-striking fault. Lastly, it led to larger ruptures on the northwest-striking fault.
Collapse
Affiliation(s)
- Jianchang Zheng
- Department of Mathematics and Statistics, University of Otago, Dunedin 9054, New Zealand
- Shandong Earthquake Agency, China Earthquake Administration, Jinan 250102, China; (Z.Z.); (X.L.)
| | - Zhengshuai Zhang
- Shandong Earthquake Agency, China Earthquake Administration, Jinan 250102, China; (Z.Z.); (X.L.)
| | - Xiaohan Li
- Shandong Earthquake Agency, China Earthquake Administration, Jinan 250102, China; (Z.Z.); (X.L.)
| |
Collapse
|
3
|
Gabriel AA, Garagash DI, Palgunadi KH, Mai PM. Fault size-dependent fracture energy explains multiscale seismicity and cascading earthquakes. Science 2024; 385:eadj9587. [PMID: 39052808 DOI: 10.1126/science.adj9587] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Accepted: 05/29/2024] [Indexed: 07/27/2024]
Abstract
Earthquakes vary in size over many orders of magnitude, often rupturing in complex multifault and multievent sequences. Despite the large number of observed earthquakes, the scaling of the earthquake energy budget remains enigmatic. We propose that fundamentally different fracture processes govern small and large earthquakes. We combined seismological observations with physics-based earthquake models, finding that both dynamic weakening and restrengthening effects are non-negligible in the energy budget of small earthquakes. We established a linear scaling relationship between fracture energy and fault size and a break in scaling with slip. We applied this scaling using supercomputing and unveiled large dynamic rupture earthquake cascades involving >700 multiscale fractures within a fault damage zone. We provide a simple explanation for seismicity across all scales with implications for comprehending earthquake genesis and multifault rupture cascades.
Collapse
Affiliation(s)
- Alice-Agnes Gabriel
- Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA, USA
- Department of Earth and Environmental Sciences, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Dmitry I Garagash
- Department of Civil and Resource Engineering, Dalhousie University, Halifax, Canada
| | - Kadek H Palgunadi
- Physical Science and Engineering, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
- Geophysical Engineering Department, Institut Teknologi Sepuluh Nopember, Surabaya, Indonesia
| | - P Martin Mai
- Physical Science and Engineering, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
| |
Collapse
|
4
|
Sardeli E, Michas G, Pavlou K, Vallianatos F. Spatiotemporal Variations of the Frequency-Magnitude Distribution in the 2019 Mw 7.1 Ridgecrest, California, Earthquake Sequence. ENTROPY (BASEL, SWITZERLAND) 2023; 25:1612. [PMID: 38136492 PMCID: PMC10742953 DOI: 10.3390/e25121612] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Revised: 11/27/2023] [Accepted: 11/29/2023] [Indexed: 12/24/2023]
Abstract
Significant seismic activity has been witnessed in the area of Ridgecrest (Southern California) over the past 40 years, with the largest being the Mw 5.8 event on 20 September 1995. In July 2019, a strong earthquake of Mw 7.1, preceded by a Mw 6.4 foreshock, impacted Ridgecrest. The mainshock triggered thousands of aftershocks that were thoroughly documented along the activated faults. In this study, we analyzed the spatiotemporal variations of the frequency-magnitude distribution in the area of Ridgecrest using the fragment-asperity model derived within the framework of non-extensive statistical physics (NESP), which is well-suited for investigating complex dynamic systems with scale-invariant properties, multi-fractality, and long-range interactions. Analysis was performed for the entire duration, as well as within various time windows during 1981-2022, in order to estimate the qM parameter and to investigate how these variations are related to the dynamic evolution of seismic activity. In addition, we analyzed the spatiotemporal qM value distributions along the activated fault zone during 1981-2019 and during each month after the occurrence of the Mw 7.1 Ridgecrest earthquake. The results indicate a significant increase in the qM parameter when large-magnitude earthquakes occur, suggesting the system's transition in an out-of-equilibrium phase and its preparation for seismic energy release.
Collapse
Affiliation(s)
- Eirini Sardeli
- Section of Geophysics-Geothermics, Department of Geology and Geoenvironment, National and Kapodistrian University of Athens, 15772 Athens, Greece; (E.S.); (K.P.); (F.V.)
| | - Georgios Michas
- Section of Geophysics-Geothermics, Department of Geology and Geoenvironment, National and Kapodistrian University of Athens, 15772 Athens, Greece; (E.S.); (K.P.); (F.V.)
| | - Kyriaki Pavlou
- Section of Geophysics-Geothermics, Department of Geology and Geoenvironment, National and Kapodistrian University of Athens, 15772 Athens, Greece; (E.S.); (K.P.); (F.V.)
| | - Filippos Vallianatos
- Section of Geophysics-Geothermics, Department of Geology and Geoenvironment, National and Kapodistrian University of Athens, 15772 Athens, Greece; (E.S.); (K.P.); (F.V.)
- Institute of Physics of Earth’s Interior and Geohazards, UNESCO Chair on Solid Earth Physics and Geohazards Risk Reduction, Hellenic Mediterranean University Research & Innovation Center, 73133 Chania, Greece
| |
Collapse
|
5
|
Jia Z, Jin Z, Marchandon M, Ulrich T, Gabriel AA, Fan W, Shearer P, Zou X, Rekoske J, Bulut F, Garagon A, Fialko Y. The complex dynamics of the 2023 Kahramanmaraş, Turkey, Mw 7.8-7.7 earthquake doublet. Science 2023; 381:985-990. [PMID: 37535759 DOI: 10.1126/science.adi0685] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2023] [Accepted: 07/19/2023] [Indexed: 08/05/2023]
Abstract
The destructive 2023 moment magnitude (Mw) 7.8-7.7 earthquake doublet ruptured multiple segments of the East Anatolian Fault system in Turkey. We integrated multiscale seismic and space-geodetic observations with multifault kinematic inversions and dynamic rupture modeling to unravel the events' complex rupture history and stress-mediated fault interactions. Our analysis reveals three subshear slip episodes during the initial Mw 7.8 earthquake with a delayed rupture initiation to the southwest. The Mw 7.7 event occurred 9 hours later with a larger slip and supershear rupture on its western branch. Mechanically consistent dynamic models accounting for fault interactions can explain the unexpected rupture paths and require a heterogeneous background stress. Our results highlight the importance of combining near- and far-field observations with data-driven and physics-based models for seismic hazard assessment.
Collapse
Affiliation(s)
- Zhe Jia
- Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92093, USA
| | - Zeyu Jin
- Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92093, USA
| | - Mathilde Marchandon
- Department of Earth and Environmental Sciences, Ludwig-Maximilians-Universität München, 80539 Munich, Germany
| | - Thomas Ulrich
- Department of Earth and Environmental Sciences, Ludwig-Maximilians-Universität München, 80539 Munich, Germany
| | - Alice-Agnes Gabriel
- Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92093, USA
- Department of Earth and Environmental Sciences, Ludwig-Maximilians-Universität München, 80539 Munich, Germany
| | - Wenyuan Fan
- Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92093, USA
| | - Peter Shearer
- Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92093, USA
| | - Xiaoyu Zou
- Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92093, USA
| | - John Rekoske
- Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92093, USA
| | - Fatih Bulut
- Geodesy Department, Bogazici University Kandilli Observatory and Earthquake Research Institute, Istanbul 34342, Turkey
| | - Aslı Garagon
- Geodesy Department, Bogazici University Kandilli Observatory and Earthquake Research Institute, Istanbul 34342, Turkey
| | - Yuri Fialko
- Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92093, USA
| |
Collapse
|
6
|
Li J, Kim T, Lapusta N, Biondi E, Zhan Z. The break of earthquake asperities imaged by distributed acoustic sensing. Nature 2023; 620:800-806. [PMID: 37532935 DOI: 10.1038/s41586-023-06227-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Accepted: 05/16/2023] [Indexed: 08/04/2023]
Abstract
Rupture imaging of megathrust earthquakes with global seismic arrays revealed frequency-dependent rupture signatures1-4, but the role of high-frequency radiators remains unclear3-5. Similar observations of the more abundant crustal earthquakes could provide critical constraints but are rare without ultradense local arrays6,7. Here we use distributed acoustic sensing technology8,9 to image the high-frequency earthquake rupture radiators. By converting a 100-kilometre dark-fibre cable into a 10,000-channel seismic array, we image four high-frequency subevents for the 2021 Antelope Valley, California, moment-magnitude 6.0 earthquake. After comparing our results with long-period moment-release10,11 and dynamic rupture simulations, we suggest that the imaged subevents are due to the breaking of fault asperities-stronger spots or pins on the fault-that substantially modulate the overall rupture behaviour. An otherwise fading rupture propagation could be promoted by the breaking of fault asperities in a cascading sequence. This study highlights how we can use the extensive pre-existing fibre networks12 as high-frequency seismic antennas to systematically investigate the rupture process of regional moderate-sized earthquakes. Coupled with dynamic rupture modelling, it could improve our understanding of earthquake rupture dynamics.
Collapse
Affiliation(s)
- Jiaxuan Li
- Seismological Laboratory, Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA, USA.
| | - Taeho Kim
- Mechanical and Civil Engineering, Division of Engineering and Applied Science, California Institute of Technology, Pasadena, CA, USA
| | - Nadia Lapusta
- Seismological Laboratory, Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA, USA
- Mechanical and Civil Engineering, Division of Engineering and Applied Science, California Institute of Technology, Pasadena, CA, USA
| | - Ettore Biondi
- Seismological Laboratory, Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA, USA
| | - Zhongwen Zhan
- Seismological Laboratory, Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA, USA
| |
Collapse
|
7
|
Nanjo KZ, Yukutake Y, Kumazawa T. Activated volcanism of Mount Fuji by the 2011 Japanese large earthquakes. Sci Rep 2023; 13:10562. [PMID: 37386094 DOI: 10.1038/s41598-023-37735-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Accepted: 06/27/2023] [Indexed: 07/01/2023] Open
Abstract
The relation between earthquakes and volcanic eruptions, each of which is manifested by large-scale tectonic plate and mantle motions, has been widely discussed. Mount Fuji, in Japan, last erupted in 1707, paired with a magnitude (M)-9-class earthquake 49 days prior. Motivated by this pairing, previous studies investigated its effect on Mount Fuji after both the 2011 M9 Tohoku megaquake and a triggered M5.9 Shizuoka earthquake 4 days later at the foot of the volcano, but reported no potential to erupt. More than 300 years have already passed since the 1707 eruption, and even though consequences to society caused by the next eruption are already being considered, the implications for future volcanism remain uncertain. This study shows how volcanic low-frequency earthquakes (LFEs) in the deep part of the volcano revealed unrecognized activation after the Shizuoka earthquake. Our analyses also show that despite an increase in the rate of occurrence of LFEs, these did not return to pre-earthquake levels, indicating a change in the magma system. Our results demonstrate that the volcanism of Mount Fuji was reactivated by the Shizuoka earthquake, implying that this volcano is sufficiently sensitive to external events that are considered to be enough to trigger eruptions.
Collapse
Affiliation(s)
- K Z Nanjo
- Global Center for Asian and Regional Research, University of Shizuoka, 3-6-1 Takajo, Aoi-Ku, Shizuoka, 420-0839, Japan.
- Center for Integrated Research and Education of Natural Hazards, Shizuoka University, 836 Oya, Suruga-Ku, Shizuoka, 422-8529, Japan.
- Institute of Statistical Mathematics, 10-3 Midori-Cho, Tachikawa, Tokyo, 190-8562, Japan.
- Japan Agency for Marine-Earth Science and Technology, Yokohama Institute for Earth Sciences, 3173-25 Showa-Machi, Kanazawa-Ku, Yokohama, Kanagawa, 236-0001, Japan.
| | - Y Yukutake
- Earthquake Research Institute, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-Ku, Tokyo, 113-0032, Japan
| | - T Kumazawa
- Institute of Statistical Mathematics, 10-3 Midori-Cho, Tachikawa, Tokyo, 190-8562, Japan
| |
Collapse
|
8
|
Taufiqurrahman T, Gabriel AA, Li D, Ulrich T, Li B, Carena S, Verdecchia A, Gallovič F. Dynamics, interactions and delays of the 2019 Ridgecrest rupture sequence. Nature 2023:10.1038/s41586-023-05985-x. [PMID: 37225989 DOI: 10.1038/s41586-023-05985-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Accepted: 03/20/2023] [Indexed: 05/26/2023]
Abstract
The observational difficulties and the complexity of earthquake physics have rendered seismic hazard assessment largely empirical. Despite increasingly high-quality geodetic, seismic and field observations, data-driven earthquake imaging yields stark differences and physics-based models explaining all observed dynamic complexities are elusive. Here we present data-assimilated three-dimensional dynamic rupture models of California's biggest earthquakes in more than 20 years: the moment magnitude (Mw) 6.4 Searles Valley and Mw 7.1 Ridgecrest sequence, which ruptured multiple segments of a non-vertical quasi-orthogonal conjugate fault system1. Our models use supercomputing to find the link between the two earthquakes. We explain strong-motion, teleseismic, field mapping, high-rate global positioning system and space geodetic datasets with earthquake physics. We find that regional structure, ambient long- and short-term stress, and dynamic and static fault system interactions driven by overpressurized fluids and low dynamic friction are conjointly crucial to understand the dynamics and delays of the sequence. We demonstrate that a joint physics-based and data-driven approach can be used to determine the mechanics of complex fault systems and earthquake sequences when reconciling dense earthquake recordings, three-dimensional regional structure and stress models. We foresee that physics-based interpretation of big observational datasets will have a transformative impact on future geohazard mitigation.
Collapse
Affiliation(s)
- Taufiq Taufiqurrahman
- Department of Earth and Environmental Sciences, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Alice-Agnes Gabriel
- Department of Earth and Environmental Sciences, Ludwig-Maximilians-Universität München, Munich, Germany.
- Institute of Geophysics and Planetary Physics, Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA, USA.
| | - Duo Li
- Department of Earth and Environmental Sciences, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Thomas Ulrich
- Department of Earth and Environmental Sciences, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Bo Li
- Department of Earth and Environmental Sciences, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Sara Carena
- Department of Earth and Environmental Sciences, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Alessandro Verdecchia
- Department of Earth and Planetary Sciences, McGill University, Montreal, Quebec, Canada
- Institute of Geology, Mineralogy and Geophysics, Ruhr-University Bochum, Bochum, Germany
| | - František Gallovič
- Department of Geophysics, Faculty of Mathematics and Physics, Charles University, Prague, Czech Republic
| |
Collapse
|
9
|
Nevitt JM, Brooks BA, Hardebeck JL, Aagaard BT. 2019 M7.1 Ridgecrest earthquake slip distribution controlled by fault geometry inherited from Independence dike swarm. Nat Commun 2023; 14:1546. [PMID: 36941244 PMCID: PMC10027285 DOI: 10.1038/s41467-023-36840-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Accepted: 02/17/2023] [Indexed: 03/23/2023] Open
Abstract
Faults often form through reactivation of pre-existing structures, developing geometries and mechanical properties specific to the system's geologic inheritance. Competition between fault geometry and other factors (e.g., lithology) to control slip at Earth's surface is an open question that is central to our knowledge of fault processes and seismic hazards. Here we use remote sensing data and field observations to investigate the origin of the 2019 M7.1 Ridgecrest, California, earthquake rupture geometry and test its impact on the slip distribution observed at Earth's surface. Common geometries suggest the fault system evolved through reactivation of structures within the surrounding Independence dike swarm (IDS). Mechanical models testing a range of fault geometries and stress fields indicate that the inherited rupture geometry strongly controlled the M7.1 earthquake slip distribution. These results motivate revisiting the development of other large-magnitude earthquake ruptures (1992 M7.3 Landers, 1999 M7.1 Hector Mine) and tectonic provinces within the IDS.
Collapse
Affiliation(s)
- Johanna M Nevitt
- U.S. Geological Survey, Earthquake Science Center, Moffett Field, CA, USA.
| | - Benjamin A Brooks
- U.S. Geological Survey, Earthquake Science Center, Moffett Field, CA, USA
| | - Jeanne L Hardebeck
- U.S. Geological Survey, Earthquake Science Center, Moffett Field, CA, USA
| | - Brad T Aagaard
- U.S. Geological Survey, Geological Hazards Science Center, Golden, CO, USA
| |
Collapse
|
10
|
Abstract
The deep magmatic architecture of the Hawaiian volcanic system is central to understanding the transport of magma from the upper mantle to the individual volcanoes. We leverage advances in earthquake monitoring with deep learning algorithms to image the structures underlying a major mantle earthquake swarm of nearly 200,000 events that rapidly accelerated after the 2018 Kīlauea caldera collapse. At depths of 36 to 43 kilometers, we resolve a 15-kilometers-long collection of near-horizontal sheeted structures that we identify as a sill complex. These sills connect to the lower depths of Kīlauea's plumbing by a 25-kilometers-long belt of seismicity. Additionally, a column of seismicity links the sill complex to a shallow décollement near Mauna Loa. These findings implicate the mantle sill complex as a nexus for magma transport beneath Hawai'i and furthermore indicate widespread magmatic connectivity in the volcanic system.
Collapse
Affiliation(s)
- John D Wilding
- Seismological Laboratory, California Institute of Technology, Pasadena, CA, USA
| | - Weiqiang Zhu
- Seismological Laboratory, California Institute of Technology, Pasadena, CA, USA
| | - Zachary E Ross
- Seismological Laboratory, California Institute of Technology, Pasadena, CA, USA
| | - Jennifer M Jackson
- Seismological Laboratory, California Institute of Technology, Pasadena, CA, USA
| |
Collapse
|
11
|
Cartwright-Taylor A, Mangriotis MD, Main IG, Butler IB, Fusseis F, Ling M, Andò E, Curtis A, Bell AF, Crippen A, Rizzo RE, Marti S, Leung DDV, Magdysyuk OV. Seismic events miss important kinematically governed grain scale mechanisms during shear failure of porous rock. Nat Commun 2022; 13:6169. [PMID: 36257960 PMCID: PMC9579157 DOI: 10.1038/s41467-022-33855-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2021] [Accepted: 10/04/2022] [Indexed: 11/09/2022] Open
Abstract
Catastrophic failure in brittle, porous materials initiates when smaller-scale fractures localise along an emergent fault zone in a transition from stable crack growth to dynamic rupture. Due to the rapid nature of this critical transition, the precise micro-mechanisms involved are poorly understood and difficult to image directly. Here, we observe these micro-mechanisms directly by controlling the microcracking rate to slow down the transition in a unique rock deformation experiment that combines acoustic monitoring (sound) with contemporaneous in-situ x-ray imaging (vision) of the microstructure. We find seismic amplitude is not always correlated with local imaged strain; large local strain often occurs with small acoustic emissions, and vice versa. Local strain is predominantly aseismic, explained in part by grain/crack rotation along an emergent shear zone, and the shear fracture energy calculated from local dilation and shear strain on the fault is half of that inferred from the bulk deformation.
Collapse
Affiliation(s)
| | | | - Ian G Main
- School of GeoSciences, University of Edinburgh, Edinburgh, UK
| | - Ian B Butler
- School of GeoSciences, University of Edinburgh, Edinburgh, UK
| | - Florian Fusseis
- School of GeoSciences, University of Edinburgh, Edinburgh, UK
| | - Martin Ling
- Independent Electronics Developer, Edinburgh Hacklab, Edinburgh, UK
| | - Edward Andò
- EPFL Center for Imaging, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Andrew Curtis
- School of GeoSciences, University of Edinburgh, Edinburgh, UK
| | - Andrew F Bell
- School of GeoSciences, University of Edinburgh, Edinburgh, UK
| | - Alyssa Crippen
- School of GeoSciences, University of Edinburgh, Edinburgh, UK
| | - Roberto E Rizzo
- School of GeoSciences, University of Edinburgh, Edinburgh, UK.,Department of Earth Sciences, University of Florence, Via La Pira 4, 50121, Florence, Italy
| | - Sina Marti
- School of GeoSciences, University of Edinburgh, Edinburgh, UK
| | - Derek D V Leung
- School of GeoSciences, University of Edinburgh, Edinburgh, UK
| | - Oxana V Magdysyuk
- Beamline I12-JEEP, Diamond Light Source Ltd., Harwell Science and Innovation Campus, Didcot, UK
| |
Collapse
|
12
|
Collettini C, Barchi MR, De Paola N, Trippetta F, Tinti E. Rock and fault rheology explain differences between on fault and distributed seismicity. Nat Commun 2022; 13:5627. [PMID: 36163188 PMCID: PMC9512795 DOI: 10.1038/s41467-022-33373-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Accepted: 09/15/2022] [Indexed: 11/17/2022] Open
Abstract
Analysis of seismicity can illuminate active fault zone structures but also deformation within large volumes of the seismogenic zone. For the Mw 6.5 2016-2017 Central Italy seismic sequence, seismicity not only localizes along the major structures hosting the mainshocks (on-fault seismicity), but also occurs within volumes of Triassic Evaporites, TE, composed of alternated anhydrites and dolostones. These volumes of distributed microseismicity show a different frequency-magnitude distribution than on-fault seismicity. We interpret that, during the sequence, shear strain-rate increase, and fluid overpressure promoted widespread ductile deformation within TE that light-up with distributed microseismicity. This interpretation is supported by field and laboratory observations showing that TE background ductile deformation is complex and dominated by distributed failure and folding of the anhydrites associated with boudinage hydro-fracturing and faulting of dolostones. Our results indicate that ductile crustal deformation can cause distributed microseismicity, which obeys to different scaling laws than on-fault seismicity occurring on structures characterized by elasto-frictional stick-slip behaviour.
Collapse
Affiliation(s)
- C Collettini
- Dipartimento di Scienze della Terra, Università di Roma La Sapienza, Rome, Italy.
- Istituto Nazionale di Geofisica e Vulcanologia (INGV), Rome, Italy.
- Consorzio Interuniversitario Nazionale per la Scienza e Tecnologia dei Materiali, Firenze, Italy.
| | - M R Barchi
- Dipartimento di Fisica e Geologia Università degli Studi di Perugia, Perugia, Italy
| | - N De Paola
- Department of Earth Sciences, Durham University, Durham, UK
| | - F Trippetta
- Dipartimento di Scienze della Terra, Università di Roma La Sapienza, Rome, Italy
- Consorzio Interuniversitario Nazionale per la Scienza e Tecnologia dei Materiali, Firenze, Italy
| | - E Tinti
- Dipartimento di Scienze della Terra, Università di Roma La Sapienza, Rome, Italy
- Istituto Nazionale di Geofisica e Vulcanologia (INGV), Rome, Italy
| |
Collapse
|
13
|
Correlation between seismic activity and tidal stress perturbations highlights growing instability within the brittle crust. Sci Rep 2022; 12:7109. [PMID: 35501477 PMCID: PMC9061777 DOI: 10.1038/s41598-022-11328-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Accepted: 04/21/2022] [Indexed: 12/19/2022] Open
Abstract
Faults become more and more responsive to stress perturbations as instability mounts. We utilize this property in order to identify the different phases of the seismic cycle. Our analysis provides new insights about the features of impending mainshocks, which are proposed to emerge from a large-scale crustal-weakening preparation process whose duration depends on their seismic moments, according to the power-law T \documentclass[12pt]{minimal}
\usepackage{amsmath}
\usepackage{wasysym}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsbsy}
\usepackage{mathrsfs}
\usepackage{upgreek}
\setlength{\oddsidemargin}{-69pt}
\begin{document}$$\propto$$\end{document}∝ M\documentclass[12pt]{minimal}
\usepackage{amsmath}
\usepackage{wasysym}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsbsy}
\usepackage{mathrsfs}
\usepackage{upgreek}
\setlength{\oddsidemargin}{-69pt}
\begin{document}$$_{0}^{1/3}$$\end{document}01/3 for M\documentclass[12pt]{minimal}
\usepackage{amsmath}
\usepackage{wasysym}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsbsy}
\usepackage{mathrsfs}
\usepackage{upgreek}
\setlength{\oddsidemargin}{-69pt}
\begin{document}$$_{0}$$\end{document}0\documentclass[12pt]{minimal}
\usepackage{amsmath}
\usepackage{wasysym}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsbsy}
\usepackage{mathrsfs}
\usepackage{upgreek}
\setlength{\oddsidemargin}{-69pt}
\begin{document}$$\le$$\end{document}≤ 10\documentclass[12pt]{minimal}
\usepackage{amsmath}
\usepackage{wasysym}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsbsy}
\usepackage{mathrsfs}
\usepackage{upgreek}
\setlength{\oddsidemargin}{-69pt}
\begin{document}$$^{19}$$\end{document}19 N m. Moreover, further studies are performed about the impact of tidal stress perturbation on seismicity; in particular, the relationship between frequency-magnitude scaling and perturbations is discussed, showing that the sensitivity of earthquakes to solid Earth tides decreases as their magnitudes increase.
Collapse
|
14
|
Cross-platform analysis of public responses to the 2019 Ridgecrest earthquake sequence on Twitter and Reddit. Sci Rep 2022; 12:1634. [PMID: 35102161 PMCID: PMC8803888 DOI: 10.1038/s41598-022-05359-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Accepted: 01/04/2022] [Indexed: 11/23/2022] Open
Abstract
Online social networks (OSNs) have become a powerful tool to study collective human responses to extreme events such as earthquakes. Most previous research concentrated on a single platform and utilized users’ behaviors on a single platform to study people’s general responses. In this study, we explore the characteristics of people’s behaviors on different OSNs and conduct a cross-platform analysis of public responses to earthquakes. Our findings support the Uses and Gratification theory that users on Reddit and Twitter are engaging with platforms that they may feel best reflect their sense of self. Using the 2019 Ridgecrest earthquakes as our study cases, we collected 510,579 tweets and 45,770 Reddit posts (including 1437 submissions and 44,333 comments) to answer the following research questions: (1) What were the similarities and differences between public responses on Twitter and Reddit? (2) Considering the different mechanisms of Twitter and Reddit, what unique information of public responses can we learn from Reddit as compared with Twitter? By answering these research questions, we aim to bridge the gap of cross-platform public responses research towards natural hazards. Our study evinces that the users on the two different platforms have both different topics of interest and different sentiments towards the same earthquake, which indicates the necessity of investigating cross-platform OSNs to reveal a more comprehensive picture of people’s general public responses towards certain disasters. Our analysis also finds that r/conspiracy subreddit is one of the major venues where people discuss the 2019 Ridgecrest earthquakes on Reddit and different misinformation/conspiracies spread on Twitter and Reddit platforms (e.g., “Big one is coming” on Twitter and “Nuclear test” on Reddit).
Collapse
|
15
|
Ionospheric Disturbances Observed Following the Ridgecrest Earthquake of 4 July 2019 in California, USA. REMOTE SENSING 2022. [DOI: 10.3390/rs14010188] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Earthquakes are known to generate disturbances in the ionosphere. Such disturbances, referred to as co-seismic ionospheric disturbances, or ionoquakes, were previously reported for large earthquakes with magnitudes Mw≥ 6.6. This paper reports ionoquakes associated with the Ridgecrest earthquakes of magnitude (Mw=6.4), that occurred on 4 July 2019 in California, USA. The ionoquakes manifested in total electron content (TEC) in the form of traveling ionospheric disturbances (TIDs) within 1 h from the mainshock onset. These seismic-origin TIDs have unique wave characteristics that distinguish them from TIDs of non-seismic origin arising from a moderate geomagnetic activity on the same day. Moreover, in the space-time domain of the detection of seismic-origin TIDs, TIDs are absent on the day before and day after the earthquake day. Their spectral characteristics relate them to the Earth’s normal modes and atmospheric resonance modes. We found the ground velocity associated with the mainshock, rather than the ground displacement, satisfies the threshold criteria for detectable ionoquakes in TEC measurements. Numerical simulation suggested that the coupled seismo–atmosphere–ionosphere (SAI) dynamics energized by the atmospheric waves are responsible for the generation of ionoquakes. This study’s findings demonstrate the potential of using TEC measurement to detect the ionospheric counterparts of moderate earthquakes.
Collapse
|
16
|
Kim J, Holt WE, Bahadori A, Shen W. Repeating Nontectonic Seasonal Stress Changes and a Possible Triggering Mechanism of the 2019 Ridgecrest Earthquake Sequence in California. JOURNAL OF GEOPHYSICAL RESEARCH. SOLID EARTH 2021; 126:e2021JB022188. [PMID: 35860427 PMCID: PMC9285800 DOI: 10.1029/2021jb022188] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 09/08/2021] [Accepted: 09/10/2021] [Indexed: 06/15/2023]
Abstract
Here we characterize the 13-year history of nontectonic horizontal strain anomalies across the regions surrounding Ridgecrest, CA, using cGPS data from January 2007. This time-dependent model reveals a seasonality in the nontectonic strain anomalies and the associated Coulomb stress changes of ∼±0.5-2 kPa. In the area surrounding the epicenters of the 2019 Ridgecrest earthquake sequence of July, we find that the seasonal preseismic Coulomb stress changes peaked every early summer (May and June) during the last 13 years including during June 2019, a month prior to the large events. In addition, our statistical tests confirm that more strike-slip earthquakes (Mw ≥ 2) occur during times when seasonal stress changes are increasing on right-lateral faults in comparison with times when stresses are decreasing. These results suggest that the timing of the 2019 Ridgecrest earthquakes may have been modulated by nontectonic seasonal stress changes. The dynamic source of the seasonal nontectonic strain/stress anomalies, however, remains enigmatic. We discuss a possible combination of driving forces that may be attributable for the seasonal variations in nontectonic strain/stress anomalies, which captured in cGPS measurements.
Collapse
Affiliation(s)
- Jeonghyeop Kim
- Department of GeosciencesStony Brook UniversityStony BrookNYUSA
| | - William E. Holt
- Department of GeosciencesStony Brook UniversityStony BrookNYUSA
| | | | - Weisen Shen
- Department of GeosciencesStony Brook UniversityStony BrookNYUSA
| |
Collapse
|
17
|
Gao Y, Duan H, Zhang Y, Chen J, Jian H, Wu R, Yin W. Coseismic fault-slip distribution of the 2019 Ridgecrest Mw6.4 and Mw7.1 earthquakes. Sci Rep 2021; 11:14188. [PMID: 34244533 PMCID: PMC8270957 DOI: 10.1038/s41598-021-93521-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Accepted: 06/24/2021] [Indexed: 11/09/2022] Open
Abstract
The 2019 Ridgecrest, California seismic sequence, including an Mw6.4 foreshock and Mw7.1 mainshock, represent the largest regional seismic events within the past 20 years. To obtain accurate coseismic fault-slip distribution, we used precise positioning data of small earthquakes from January 2019 to October 2020 to determine the dip parameters of the eight fault geometry, and used the Interferometric Synthetic Aperture Radar (InSAR) data processed by Xu et al. (Seismol Res Lett 91(4):1979-1985, 2020) at UCSD to constrain inversion of the fault-slip distribution of both earthquakes. The results showed that all faults were sinistral strike-slips with minor dip-slip components, exception for dextral strike-slip fault F2. Fault-slip mainly occurred at depths of 0-12 km, with a maximum slip of 3.0 m. The F1 fault contained two slip peaks located at 2 km of fault S4 and 6 km of fault S5 depth, the latter being located directly above the Mw7.1hypocenter. Two slip peaks with maximum slip of 1.5 m located 8 and 20 km from the SW endpoint of the F2 fault were also identified, and the latter corresponds to the Mw6.4 earthquake. We also analyzed the influence of different inversion parameters on the fault slip distribution, and found that the slip momentum smoothing condition was more suitable for the inversion of the earthquakes slip distribution than the stress-drop smoothing condition.
Collapse
Affiliation(s)
- Yang Gao
- College of Geological Engineering and Geomatics, Chang'an University, Xi'an, 710064, Shaanxi, China
| | - HuRong Duan
- College of Geomatics, Xi'an University of Science and Technology, Xi'an, 710054, Shaanxi, China.
| | - YongZhi Zhang
- College of Geological Engineering and Geomatics, Chang'an University, Xi'an, 710064, Shaanxi, China
| | - JiaYing Chen
- College of Geomatics, Xi'an University of Science and Technology, Xi'an, 710054, Shaanxi, China
| | - HeTing Jian
- College of Geomatics, Xi'an University of Science and Technology, Xi'an, 710054, Shaanxi, China
| | - Rui Wu
- College of Geomatics, Xi'an University of Science and Technology, Xi'an, 710054, Shaanxi, China
| | - WenHao Yin
- Xi'an Institute of Surveying and Mapping, Xi'an, 710054, Shaanxi, China
| |
Collapse
|
18
|
Ridgecrest aftershocks at Coso suppressed by thermal destressing. Nature 2021; 595:70-74. [PMID: 34194023 DOI: 10.1038/s41586-021-03601-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2020] [Accepted: 04/30/2021] [Indexed: 11/08/2022]
Abstract
Geothermal and volcanic areas are prone to earthquake triggering1,2. The Coso geothermal field in California lies just north of the surface ruptures driven by the 2019 Ridgecrest earthquake (moment magnitude Mw = 7.1), in an area where changes in coseismic stress should have triggered aftershocks3,4. However, no aftershocks were observed there4. Here we show that 30 years of geothermal heat production at Coso depleted shear stresses within the geothermal reservoir. Thermal contraction of the reservoir initially induced substantial seismicity, as observed in the Coso geothermal reservoir, but subsequently depleted the stress available to drive the aftershocks during the Ridgecrest sequence. This destressing changed the faulting style of the reservoir and impeded aftershock triggering. Although unlikely to have been the case for the Ridgecrest earthquake, such a destressed zone could, in principle, impede the propagation of a large earthquake.
Collapse
|
19
|
Brissaud Q, Krishnamoorthy S, Jackson JM, Bowman DC, Komjathy A, Cutts JA, Zhan Z, Pauken MT, Izraelevitz JS, Walsh GJ. The First Detection of an Earthquake From a Balloon Using Its Acoustic Signature. GEOPHYSICAL RESEARCH LETTERS 2021; 48:e2021GL093013. [PMID: 34433991 PMCID: PMC8365762 DOI: 10.1029/2021gl093013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Revised: 04/20/2021] [Accepted: 04/23/2021] [Indexed: 06/13/2023]
Abstract
Extreme temperature and pressure conditions on the surface of Venus present formidable technological challenges against performing ground-based seismology. Efficient coupling between the Venusian atmosphere and the solid planet theoretically allows the study of seismically generated acoustic waves using balloons in the upper atmosphere, where conditions are far more clement. However, earthquake detection from a balloon has never been demonstrated. We present the first detection of an earthquake from a balloon-borne microbarometer near Ridgecrest, CA in July 2019 and include a detailed analysis of the dependence of seismic infrasound, as measured from a balloon on earthquake source parameters, topography, and crustal and atmospheric structure. Our comprehensive analysis of seismo-acoustic phenomenology demonstrates that seismic activity is detectable from a high-altitude platform on Earth, and that Rayleigh wave-induced infrasound can be used to constrain subsurface velocities, paving the way for the detection and characterization of such signals on Venus.
Collapse
Affiliation(s)
- Quentin Brissaud
- Seismological LaboratoryCalifornia Institute of TechnologyPasadenaCAUSA
- the Norwegian Seismic Array (NORSAR)OsloNorway
| | | | | | | | - Attila Komjathy
- Jet Propulsion LaboratoryCalifornia Institute of TechnologyPasadenaCAUSA
| | - James A. Cutts
- Jet Propulsion LaboratoryCalifornia Institute of TechnologyPasadenaCAUSA
| | - Zhongwen Zhan
- Seismological LaboratoryCalifornia Institute of TechnologyPasadenaCAUSA
| | - Michael T. Pauken
- Jet Propulsion LaboratoryCalifornia Institute of TechnologyPasadenaCAUSA
| | | | - Gerald J. Walsh
- Jet Propulsion LaboratoryCalifornia Institute of TechnologyPasadenaCAUSA
| |
Collapse
|
20
|
Gabriel AA, Li D, Chiocchetti S, Tavelli M, Peshkov I, Romenski E, Dumbser M. A unified first-order hyperbolic model for nonlinear dynamic rupture processes in diffuse fracture zones. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2021; 379:20200130. [PMID: 33715407 PMCID: PMC8059614 DOI: 10.1098/rsta.2020.0130] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Accepted: 09/28/2020] [Indexed: 06/12/2023]
Abstract
Earthquake fault zones are more complex, both geometrically and rheologically, than an idealized infinitely thin plane embedded in linear elastic material. To incorporate nonlinear material behaviour, natural complexities and multi-physics coupling within and outside of fault zones, here we present a first-order hyperbolic and thermodynamically compatible mathematical model for a continuum in a gravitational field which provides a unified description of nonlinear elasto-plasticity, material damage and of viscous Newtonian flows with phase transition between solid and liquid phases. The fault geometry and secondary cracks are described via a scalar function ξ ∈ [0, 1] that indicates the local level of material damage. The model also permits the representation of arbitrarily complex geometries via a diffuse interface approach based on the solid volume fraction function α ∈ [0, 1]. Neither of the two scalar fields ξ and α needs to be mesh-aligned, allowing thus faults and cracks with complex topology and the use of adaptive Cartesian meshes (AMR). The model shares common features with phase-field approaches, but substantially extends them. We show a wide range of numerical applications that are relevant for dynamic earthquake rupture in fault zones, including the co-seismic generation of secondary off-fault shear cracks, tensile rock fracture in the Brazilian disc test, as well as a natural convection problem in molten rock-like material. This article is part of the theme issue 'Fracture dynamics of solid materials: from particles to the globe'.
Collapse
Affiliation(s)
- A.-A. Gabriel
- Ludwig-Maximilians-Universität München, Theresienstr. 41, 80333 München, Germany
| | - D. Li
- Ludwig-Maximilians-Universität München, Theresienstr. 41, 80333 München, Germany
| | - S. Chiocchetti
- Laboratory of Applied Mathematics, University of Trento, Via Mesiano, 77, 38123 Trento, Italy
| | - M. Tavelli
- Laboratory of Applied Mathematics, University of Trento, Via Mesiano, 77, 38123 Trento, Italy
| | - I. Peshkov
- Laboratory of Applied Mathematics, University of Trento, Via Mesiano, 77, 38123 Trento, Italy
| | - E. Romenski
- Sobolev Institute of Mathematics, 4 Acad. Koptyug Avenue, 630090 Novosibirsk, Russia
- Laboratory of Applied Mathematics, University of Trento, Via Mesiano, 77, 38123 Trento, Italy
| | - M. Dumbser
- Laboratory of Applied Mathematics, University of Trento, Via Mesiano, 77, 38123 Trento, Italy
| |
Collapse
|
21
|
An Improved Quadtree Sampling Method for InSAR Seismic Deformation Inversion. REMOTE SENSING 2021. [DOI: 10.3390/rs13091678] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
With the development of interferometric synthetic aperture radar (InSAR), the seismic deformation observation density increases sharply. Data down-sampling can effectively reduce the observation density and the computational cost for subsequent researches. Considering the saliency of the deformation field, we introduce a saliency-based quadtree algorithm for down-sampling (SQS). Three simulation experiments show that SQS can effectively distinguish the near-field and far-field deformation, as well as reduce the amount of observation, while keeping the detailed information of the main deformation near the fault. SQS can avoid the interference of far-field local deformation better than the traditional quadtree sampling algorithm (QS), thus obtaining better inversion results. We took the Dingri earthquake on 20 March 2020 as a case study to verify the advantages of SQS in dealing with real earthquake deformation. We obtained the co-seismic deformation from the ascending and descending Sentinel-1 for the Dingri earthquake, using QS and SQS for sampling and inversion separately. The results show the advantages of SQS in data volume reduction, observation distribution, anti-interference of local deformation, and inversion accuracy. Our preferred solution based on SQS shows that the Dingri earthquake was caused by a normal fault slip. The main slip area is 2–5.5 km deep with a maximum slip of 0.68 m. The estimated geodetic moment is 3.14 × 1017 Nm, corresponding to a magnitude of Mw5.63.
Collapse
|
22
|
Jiang J, Bock Y, Klein E. Coevolving early afterslip and aftershock signatures of a San Andreas fault rupture. SCIENCE ADVANCES 2021; 7:7/15/eabc1606. [PMID: 33837071 PMCID: PMC8034852 DOI: 10.1126/sciadv.abc1606] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2020] [Accepted: 02/23/2021] [Indexed: 05/26/2023]
Abstract
Large earthquakes often lead to transient deformation and enhanced seismic activity, with their fastest evolution occurring at the early, ephemeral post-rupture period. Here, we investigate this elusive phase using geophysical observations from the 2004 moment magnitude 6.0 Parkfield, California, earthquake. We image continuously evolving afterslip, along with aftershocks, on the San Andreas fault over a minutes-to-days postseismic time span. Our results reveal a multistage scenario, including immediate onset of afterslip following tens-of-seconds-long coseismic shaking, short-lived slip reversals within minutes, expanding afterslip within hours, and slip migration between subparallel fault strands within days. The early afterslip and associated stress changes appear synchronized with local aftershock rates, with increasing afterslip often preceding larger aftershocks, suggesting the control of afterslip on fine-scale aftershock behavior. We interpret complex shallow processes as dynamic signatures of a three-dimensional fault-zone structure. These findings highlight important roles of aseismic source processes and structural factors in seismicity evolution, offering potential prospects for improving aftershock forecasts.
Collapse
Affiliation(s)
- Junle Jiang
- School of Geosciences, University of Oklahoma, Norman, OK, USA.
| | - Yehuda Bock
- Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA, USA
| | - Emilie Klein
- Laboratoire de Géologie, Département de Géosciences, ENS, CNRS, UMR 8538, PSL Research University, France
| |
Collapse
|
23
|
Consecutive ruptures on a complex conjugate fault system during the 2018 Gulf of Alaska earthquake. Sci Rep 2021; 11:5979. [PMID: 33727671 PMCID: PMC7966370 DOI: 10.1038/s41598-021-85522-w] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Accepted: 02/26/2021] [Indexed: 01/31/2023] Open
Abstract
We developed a flexible finite-fault inversion method for teleseismic P waveforms to obtain a detailed rupture process of a complex multiple-fault earthquake. We estimate the distribution of potency-rate density tensors on an assumed model plane to clarify rupture evolution processes, including variations of fault geometry. We applied our method to the 23 January 2018 Gulf of Alaska earthquake by representing slip on a projected horizontal model plane at a depth of 33.6 km to fit the distribution of aftershocks occurring within one week of the mainshock. The obtained source model, which successfully explained the complex teleseismic P waveforms, shows that the 2018 earthquake ruptured a conjugate system of N-S and E-W faults. The spatiotemporal rupture evolution indicates irregular rupture behavior involving a multiple-shock sequence, which is likely associated with discontinuities in the fault geometry that originated from E-W sea-floor fracture zones and N-S plate-bending faults.
Collapse
|
24
|
Real-time determination of earthquake focal mechanism via deep learning. Nat Commun 2021; 12:1432. [PMID: 33664244 PMCID: PMC7933283 DOI: 10.1038/s41467-021-21670-x] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Accepted: 01/27/2021] [Indexed: 01/31/2023] Open
Abstract
An immediate report of the source focal mechanism with full automation after a destructive earthquake is crucial for timely characterizing the faulting geometry, evaluating the stress perturbation, and assessing the aftershock patterns. Advanced technologies such as Artificial Intelligence (AI) has been introduced to solve various problems in real-time seismology, but the real-time source focal mechanism is still a challenge. Here we propose a novel deep learning method namely Focal Mechanism Network (FMNet) to address this problem. The FMNet trained with 787,320 synthetic samples successfully estimates the focal mechanisms of four 2019 Ridgecrest earthquakes with magnitude larger than Mw 5.4. The network learns the global waveform characteristics from theoretical data, thereby allowing the extensive applications of the proposed method to regions of potential seismic hazards with or without historical earthquake data. After receiving data, the network takes less than two hundred milliseconds for predicting the source focal mechanism reliably on a single CPU.
Collapse
|
25
|
Surface Rupture Kinematics and Coseismic Slip Distribution during the 2019 Mw7.1 Ridgecrest, California Earthquake Sequence Revealed by SAR and Optical Images. REMOTE SENSING 2020. [DOI: 10.3390/rs12233883] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The 2019 Ridgecrest, California earthquake sequence ruptured along a complex fault system and triggered seismic and aseismic slips on intersecting faults. To characterize the surface rupture kinematics and fault slip distribution, we used optical images and Interferometric Synthetic Aperture Radar (InSAR) observations to reconstruct the displacement caused by the earthquake sequence. We further calculated curl and divergence from the north-south and east-west components, to effectively identify the surface rupture traces. The results show that the major seismogenic fault had a length of ~55 km and strike of 320° and consisted of five secondary faults. On the basis of the determined multiple-fault geometries, we inverted the coseismic slip distributions by InSAR measurements, which indicates that the Mw7.1 mainshock was dominated by the right-lateral strike-slip (maximum strike-slip of ~5.8 m at the depth of ~7.5 km), with a small dip-slip component (peaking at ~1.8 m) on an east-dipping fault. The Mw6.4 foreshock was dominated by the left-lateral strike-slip on a north-dipping fault. These earthquakes triggered obvious aseismic creep along the Garlock fault (117.3° W–117.5° W). These results are consistent with the rupture process of the earthquake sequence, which featured a complicated cascading rupture rather than a single continuous rupture front propagating along multiple faults.
Collapse
|
26
|
The Effect of Catalogue Lead Time on Medium-Term Earthquake Forecasting with Application to New Zealand Data. ENTROPY 2020; 22:e22111264. [PMID: 33287032 PMCID: PMC7712439 DOI: 10.3390/e22111264] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 11/03/2020] [Accepted: 11/04/2020] [Indexed: 11/24/2022]
Abstract
‘Every Earthquake a Precursor According to Scale’ (EEPAS) is a catalogue-based model to forecast earthquakes within the coming months, years and decades, depending on magnitude. EEPAS has been shown to perform well in seismically active regions like New Zealand (NZ). It is based on the observation that seismicity increases prior to major earthquakes. This increase follows predictive scaling relations. For larger target earthquakes, the precursor time is longer and precursory seismicity may have occurred prior to the start of the catalogue. Here, we derive a formula for the completeness of precursory earthquake contributions to a target earthquake as a function of its magnitude and lead time, where the lead time is the length of time from the start of the catalogue to its time of occurrence. We develop two new versions of EEPAS and apply them to NZ data. The Fixed Lead time EEPAS (FLEEPAS) model is used to examine the effect of the lead time on forecasting, and the Fixed Lead time Compensated EEPAS (FLCEEPAS) model compensates for incompleteness of precursory earthquake contributions. FLEEPAS reveals a space-time trade-off of precursory seismicity that requires further investigation. Both models improve forecasting performance at short lead times, although the improvement is achieved in different ways.
Collapse
|
27
|
Xu X, Sandwell DT, Ward LA, Milliner CWD, Smith-Konter BR, Fang P, Bock Y. Surface deformation associated with fractures near the 2019 Ridgecrest earthquake sequence. Science 2020; 370:605-608. [PMID: 33122385 DOI: 10.1126/science.abd1690] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Accepted: 09/11/2020] [Indexed: 11/02/2022]
Abstract
Contemporary earthquake hazard models hinge on an understanding of how strain is distributed in the crust and the ability to precisely detect millimeter-scale deformation over broad regions of active faulting. Satellite radar observations revealed hundreds of previously unmapped linear strain concentrations (or fractures) surrounding the 2019 Ridgecrest earthquake sequence. We documented and analyzed displacements and widths of 169 of these fractures. Although most fractures are displaced in the direction of the prevailing tectonic stress (prograde), a large number of them are displaced in the opposite (retrograde) direction. We developed a model to explain the existence and behavior of these displacements. A major implication is that much of the prograde tectonic strain is accommodated by frictional slip on many preexisting faults.
Collapse
Affiliation(s)
- Xiaohua Xu
- Institute of Geophysics and Planetary Physics, Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA, USA.
| | - David T Sandwell
- Institute of Geophysics and Planetary Physics, Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA, USA
| | - Lauren A Ward
- Department of Earth Sciences, University of Hawaii at Manoa, Honolulu, HI, USA
| | - Chris W D Milliner
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
| | | | - Peng Fang
- Institute of Geophysics and Planetary Physics, Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA, USA
| | - Yehuda Bock
- Institute of Geophysics and Planetary Physics, Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA, USA
| |
Collapse
|
28
|
Ross ZE, Cochran ES, Trugman DT, Smith JD. 3D fault architecture controls the dynamism of earthquake swarms. Science 2020; 368:1357-1361. [PMID: 32554593 DOI: 10.1126/science.abb0779] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Accepted: 04/28/2020] [Indexed: 11/02/2022]
Abstract
The vibrant evolutionary patterns made by earthquake swarms are incompatible with standard, effectively two-dimensional (2D) models for general fault architecture. We leverage advances in earthquake monitoring with a deep-learning algorithm to image a fault zone hosting a 4-year-long swarm in southern California. We infer that fluids are naturally injected into the fault zone from below and diffuse through strike-parallel channels while triggering earthquakes. A permeability barrier initially limits up-dip swarm migration but ultimately is circumvented. This enables fluid migration within a shallower section of the fault with fundamentally different mechanical properties. Our observations provide high-resolution constraints on the processes by which swarms initiate, grow, and arrest. These findings illustrate how swarm evolution is strongly controlled by 3D variations in fault architecture.
Collapse
Affiliation(s)
- Zachary E Ross
- Seismological Laboratory, California Institute of Technology, Pasadena, CA, USA.
| | | | - Daniel T Trugman
- Department of Geological Sciences, The University of Texas at Austin, Austin, TX, USA.,Los Alamos National Laboratory, Los Alamos, NM, USA
| | - Jonathan D Smith
- Seismological Laboratory, California Institute of Technology, Pasadena, CA, USA
| |
Collapse
|
29
|
Were changes in stress state responsible for the 2019 Ridgecrest, California, earthquakes? Nat Commun 2020; 11:3082. [PMID: 32555220 PMCID: PMC7299982 DOI: 10.1038/s41467-020-16867-5] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2020] [Accepted: 05/26/2020] [Indexed: 11/09/2022] Open
Abstract
Monitoring the Earth’s stress state plays a role in our understanding of an earthquake’s mechanism and in the distribution of hazards. Crustal deformation due to the July 2019 earthquake sequence in Ridgecrest (California) that culminated in a preceding quake of magnitude (M) 6.4 and a subsequent M7.1 quake caused stress perturbation in a nearby region, but implications of future seismicity are still uncertain. Here, the occurrence of small earthquakes is compared to larger ones, using b-values, showing that the rupture initiation from an area of low b-values, indicative of high stress, was common to both M6.4 and M7.1 quakes. The post-M7.1-quake sequence reveals that another low-b-value zone, which avoided its ruptured area, fell into an area near the Garlock fault that hosted past large earthquakes. If this area were more stressed, there would be a high-likelihood of further activation of seismicity that might influence the Garlock fault. Based on b-value mapping, the author proposes the high likelihood of future rupture in the area of the 2019 Ridgecrest earthquakes.
Collapse
|
30
|
The Multiple Aperture SAR Interferometry (MAI) Technique for the Detection of Large Ground Displacement Dynamics: An Overview. REMOTE SENSING 2020. [DOI: 10.3390/rs12071189] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
This work presents an overview of the multiple aperture synthetic aperture radar interferometric (MAI) technique, which is primarily used to measure the along-track components of the Earth’s surface deformation, by investigating its capabilities and potential applications. Such a method is widely used to monitor the time evolution of ground surface changes in areas with large deformations (e.g., due to glaciers movements or seismic episodes), permitting one to discriminate the three-dimensional (up–down, east–west, north–south) components of the Earth’s surface displacements. The MAI technique relies on the spectral diversity (SD) method, which consists of splitting the azimuth (range) Synthetic Aperture RADAR (SAR) signal spectrum into separate sub-bands to get an estimate of the surface displacement along the azimuth (sensor line-of-sight (LOS)) direction. Moreover, the SD techniques are also used to correct the atmospheric phase screen (APS) artefacts (e.g., the ionospheric and water vapor phase distortion effects) that corrupt surface displacement time-series obtained by currently available multi-temporal InSAR (MT-InSAR) tools. More recently, the SD methods have also been exploited for the fine co-registration of SAR data acquired with the Terrain Observation with Progressive Scans (TOPS) mode. This work is primarily devoted to illustrating the underlying rationale and effectiveness of the MAI and SD techniques as well as their applications. In addition, we present an innovative method to combine complementary information of the ground deformation collected from multi-orbit/multi-track satellite observations. In particular, the presented technique complements the recently developed Minimum Acceleration combination (MinA) method with MAI-driven azimuthal ground deformation measurements to obtain the time-series of the 3-D components of the deformation in areas affected by large deformation episodes. Experimental results encompass several case studies. The validity and relevance of the presented approaches are clearly demonstrated in the context of geospatial analyses.
Collapse
|
31
|
Constraints on Complex Faulting during the 1996 Ston–Slano (Croatia) Earthquake Inferred from the DInSAR, Seismological, and Geological Observations. REMOTE SENSING 2020. [DOI: 10.3390/rs12071157] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
This study, involving remote sensing, seismology, and geology, revealed complex faulting during the mainshock of the Ston–Slano earthquake sequence (5 September, 1996, Mw = 6.0). The observed DInSAR interferogram fringe patterns could not be explained by a single fault rupture. Geological investigations assigned most of the interferogram features either to previously known faults or to those newly determined by field studies. Relocation of hypocentres and reassessment of fault mechanisms provided additional constraints on the evolution of stress release during this sequence. Available data support the scenario that the mainshock started with a reverse rupture with a left-lateral component on the Slano fault 4.5 km ESE of Slano, at the depth of about 11 km. The rupture proceeded unilaterally to the NW with the velocity of about 1.5 km/s for about 11 km, where the maximum stress release occurred. DInSAR interferograms suggest that several faults were activated in the process. The rupture terminated about 20 km away from the epicentre, close to the town of Ston, where the maximum DInSAR ground displacement reached 38 cm. Such a complicated and multiple rupture has never before been documented in the Dinarides. If this proves to be a common occurrence, it can pose problems in defining realistic hazard scenarios, especially in deterministic hazard assessment.
Collapse
|