1
|
Folesky J. Different earthquake nucleation conditions revealed by stress drop and b-value mapping in the northern Chilean subduction zone. Sci Rep 2024; 14:12182. [PMID: 38806618 DOI: 10.1038/s41598-024-63015-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2024] [Accepted: 05/23/2024] [Indexed: 05/30/2024] Open
Abstract
Stress drop is an earthquake property indicative for the characteristic relation of slip to fault dimension. It is furthermore affected by fault strength, fault topography, the presence of fluids, rupture size, slip, and velocity. In this article, the stress drop image of an entire subduction zone, namely for the seismically highly active northernmost part of Chile, is combined with mapped b-values and their corresponding magnitude distribution in order to better constrain the conditions under which earthquakes of different provenances may nucleate. The underlying recent earthquake catalog contains over 180,000 events, covering 15 years of seismicity, from which more than 50,000 stress drop estimates were computed. Their spatial average segments the subduction zone into different parts, i.e., average stress drop between seismotectonic areas is different, although this difference is small compared to the natural scatter of stress drop values. By considering stress drop variations, b-value map, magnitude distribution, and thermal models, candidate earthquake nucleation mechanisms are identified which can explain the observed distributions. This is done for two exemplary regions: (1) The plate interface, where principally lower stress drop events are found, while at the same time a high spatial heterogeneity of stress drop values is observed. This indicates relatively smooth or lubricated rupture surfaces, and locally it suggests the existence of alternating regions controlled by strong asperities, weaker material, or creep. (2) The highly active intermediate depth (ID) seismicity region, where the variation of stress drop and b-value point to a gradual change of nucleation mechanism from dehydration embrittlement at the top of the ID cloud, over dehydration driven stress transfer in its central part, to thermal runaway shear mechanisms at its bottom. In both cases, the combination of stress drop and b-value distribution helps to better understand the origin and the differences of the observed seismicity.
Collapse
Affiliation(s)
- Jonas Folesky
- Freie Universität Berlin, Geophysics, Berlin, 12249, Germany.
| |
Collapse
|
2
|
Kwiatek G, Martínez-Garzón P, Becker D, Dresen G, Cotton F, Beroza GC, Acarel D, Ergintav S, Bohnhoff M. Months-long seismicity transients preceding the 2023 M W 7.8 Kahramanmaraş earthquake, Türkiye. Nat Commun 2023; 14:7534. [PMID: 38016987 PMCID: PMC10684546 DOI: 10.1038/s41467-023-42419-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Accepted: 10/11/2023] [Indexed: 11/30/2023] Open
Abstract
Short term prediction of earthquake magnitude, time, and location is currently not possible. In some cases, however, documented observations have been retrospectively considered as precursory. Here we present seismicity transients starting approx. 8 months before the 2023 MW 7.8 Kahramanmaraş earthquake on the East Anatolian Fault Zone. Seismicity is composed of isolated spatio-temporal clusters within 65 km of future epicentre, displaying non-Poissonian inter-event time statistics, magnitude correlations and low Gutenberg-Richter b-values. Local comparable seismic transients have not been observed, at least since 2014. Close to epicentre and during the weeks prior to its rupture, only scarce seismic activity was observed. The trends of seismic preparatory attributes for this earthquake follow those previously documented in both laboratory stick-slip tests and numerical models of heterogeneous earthquake rupture affecting multiple fault segments. More comprehensive earthquake monitoring together with long-term seismic records may facilitate recognizing earthquake preparation processes from other regional deformation transients.
Collapse
Affiliation(s)
- G Kwiatek
- Helmholtz Centre Potsdam GFZ German Research Centre for Geosciences, Potsdam, Germany
| | - P Martínez-Garzón
- Helmholtz Centre Potsdam GFZ German Research Centre for Geosciences, Potsdam, Germany.
| | - D Becker
- Helmholtz Centre Potsdam GFZ German Research Centre for Geosciences, Potsdam, Germany
| | - G Dresen
- Helmholtz Centre Potsdam GFZ German Research Centre for Geosciences, Potsdam, Germany
- Institute of Geosciences, University of Potsdam, Potsdam, Germany
| | - F Cotton
- Helmholtz Centre Potsdam GFZ German Research Centre for Geosciences, Potsdam, Germany
- Institute of Geosciences, University of Potsdam, Potsdam, Germany
| | - G C Beroza
- Department of Geophysics, Stanford University, Stanford, CA, USA
| | - D Acarel
- Institute of Earth and Marine Sciences, Gebze Technical University, Gebze-Kocaeli, Turkey
| | - S Ergintav
- Department of Geodesy, Kandilli Observatory and Earthquake Research Institute, Boğaziçi University, Çengelköy-Istanbul, Turkey
| | - M Bohnhoff
- Helmholtz Centre Potsdam GFZ German Research Centre for Geosciences, Potsdam, Germany
- Free University Berlin, Institute of Geological Sciences, Berlin, Germany
| |
Collapse
|
3
|
Hormazábal J, Moreno M, Ortega-Culaciati F, Báez JC, Peña C, Sippl C, González-Vidal D, Ruiz J, Metzger S, Yoshioka S. Fast relocking and afterslip-seismicity evolution following the 2015 Mw 8.3 Illapel earthquake in Chile. Sci Rep 2023; 13:19511. [PMID: 37945656 PMCID: PMC10636185 DOI: 10.1038/s41598-023-45369-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Accepted: 10/18/2023] [Indexed: 11/12/2023] Open
Abstract
Large subduction earthquakes induce complex postseismic deformation, primarily driven by afterslip and viscoelastic relaxation, in addition to interplate relocking processes. However, these signals are intricately intertwined, posing challenges in determining the timing and nature of relocking. Here, we use six years of continuous GNSS measurements (2015-2021) to study the spatiotemporal evolution of afterslip, seismicity and locking after the 2015 Illapel earthquake ([Formula: see text] 8.3). Afterslip is inverted from postseismic displacements corrected for nonlinear viscoelastic relaxation modeled using a power-law rheology, and the distribution of locking is obtained from the linear trend of GNSS stations. Our results show that afterslip is mainly concentrated in two zones surrounding the region of largest coseismic slip. The accumulated afterslip (corresponding to [Formula: see text] 7.8) exceeds 1.5 m, with aftershocks mainly occurring at the boundaries of the afterslip patches. Our results reveal that the region experiencing the largest coseismic slip undergoes rapid relocking, exhibiting the behavior of a persistent velocity weakening asperity, with no observed aftershocks or afterslip within this region during the observed period. The rapid relocking of this asperity may explain the almost regular recurrence time of earthquakes in this region, as similar events occurred in 1880 and 1943.
Collapse
Affiliation(s)
- Joaquín Hormazábal
- Department of Geophysics, Faculty of Physical and Mathematical Sciences, University of Chile, Santiago, Chile
| | - Marcos Moreno
- Department of Structural and Geotechnical Engineering, Pontificia Universidad Católica, Santiago, Chile.
- Millennium Institute of Oceanography, IMO, Concepción, Chile.
| | - Francisco Ortega-Culaciati
- Department of Geophysics, Faculty of Physical and Mathematical Sciences, University of Chile, Santiago, Chile
- Data Observatory Foundation, ANID Technology Center No. DO210001, Santiago, Chile
| | - Juan Carlos Báez
- Centro Sismológico Nacional, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Santiago, Chile
| | - Carlos Peña
- Helmholtz Centre Potsdam, GFZ German Research Centre for Geosciences, Potsdam, Germany
- Institute of Geosciences, Ruhr University Bochum, Bochum, Germany
| | - Christian Sippl
- Institute of Geophysics of the Czech Academy of Sciences, Prague, Czech Republic
| | | | - Javier Ruiz
- Department of Geophysics, Faculty of Physical and Mathematical Sciences, University of Chile, Santiago, Chile
| | - Sabrina Metzger
- Helmholtz Centre Potsdam, GFZ German Research Centre for Geosciences, Potsdam, Germany
| | - Shoichi Yoshioka
- Research Center for Urban Safety and Security, Kobe University, Rokkodai-cho 1-1, Nada Ward, Kobe, 657-8501, Japan
- Department of Planetology, Graduate School of Science, Kobe University, Rokkodai-cho 1-1, Nada Ward, Kobe, 657-8501, Japan
| |
Collapse
|
4
|
Picozzi M, Iaccarino AG, Spallarossa D. The preparatory process of the 2023 Mw 7.8 Türkiye earthquake. Sci Rep 2023; 13:17853. [PMID: 37857660 PMCID: PMC10587168 DOI: 10.1038/s41598-023-45073-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Accepted: 10/16/2023] [Indexed: 10/21/2023] Open
Abstract
To verify the existence of a preparatory process for the 6 February 2023, Mw 7.8 Kahramanmaraş earthquake, southern Türkiye, we analyze the temporal evolution of seismic catalog information for ~ 7500 earthquakes with magnitudes ML ≥ 1.5, which occurred along the main segments of the East Anatolian Fault (EAF) since 2014. We find the EAF fault segments showing different temporal patterns in the proportion of nonclustered seismicity, which we interpret as temporal variation of coupling. We also study the evolution of the b-value, fractal dimension and energy rate. These seismic features show for the Amanos and Pazarcık fault segments a long-term trend during the period 2020-2022 that might correspond to a quiescence phase. The latter is followed by a change in earthquakes clustering and characteristics that starts about eight months before the Mw 7.8 Kahramanmaraş event. Our observations confirm the existence of a long-lasting preparatory phase for the 2023, Mw 7.8 Kahramanmaraş earthquake and can stimulate new investigations on the East Anatolian Fault mechanic. Intercepting when a fault starts deviating from its steady behavior, might be the key for identifying the preparatory phase of large earthquakes and mitigate seismic risk.
Collapse
|
5
|
Bletery Q, Nocquet JM. The precursory phase of large earthquakes. Science 2023; 381:297-301. [PMID: 37471540 DOI: 10.1126/science.adg2565] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Accepted: 05/17/2023] [Indexed: 07/22/2023]
Abstract
The existence of an observable precursory phase of slip on the fault before large earthquakes has been debated for decades. Although observations preceding several large earthquakes have been proposed as possible indicators of precursory slip, these observations do not directly precede earthquakes, are not seen before most events, and are also commonly observed without being followed by earthquakes. We conducted a global search for short-term precursory slip in GPS data. We summed the displacements measured by 3026 high-rate GPS time series-projected onto the directions expected from precursory slip at the hypocenter-during 48 hours before 90 (moment magnitude ≥7) earthquakes. Our approach reveals a ≈2-hour-long exponential acceleration of slip before the ruptures, suggesting that large earthquakes start with a precursory phase of slip, which improvements in measurement precision and density could more effectively detect and possibly monitor.
Collapse
Affiliation(s)
- Quentin Bletery
- Université Côte d'Azur, IRD, CNRS, Observatoire de la Côte d'Azur, Géoazur, France
| | - Jean-Mathieu Nocquet
- Université Côte d'Azur, IRD, CNRS, Observatoire de la Côte d'Azur, Géoazur, France
- Institut de Physique du Globe de Paris, Université de Paris, CNRS, France
| |
Collapse
|
6
|
Megathrust reflectivity reveals the updip limit of the 2014 Iquique earthquake rupture. Nat Commun 2022; 13:3969. [PMID: 35803918 PMCID: PMC9270347 DOI: 10.1038/s41467-022-31448-4] [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: 08/24/2021] [Accepted: 06/08/2022] [Indexed: 11/08/2022] Open
Abstract
The updip limit of seismic rupture during a megathrust earthquake exerts a major control on the size of the resulting tsunami. Offshore Northern Chile, the 2014 Mw 8.1 Iquique earthquake ruptured the plate boundary between 19.5° and 21°S. Rupture terminated under the mid-continental slope and did not propagate updip to the trench. Here, we use state-of-the-art seismic reflection data to investigate the tectonic setting associated with the apparent updip arrest of rupture propagation at 15 km depth during the Iquique earthquake. We document a spatial correspondence between the rupture area and the seismic reflectivity of the plate boundary. North and updip of the rupture area, a coherent, highly reflective plate boundary indicates excess fluid pressure, which may prevent the accumulation of elastic strain. In contrast, the rupture area is characterized by the absence of plate boundary reflectivity, which suggests low fluid pressure that results in stress accumulation and thus controls the extent of earthquake rupture. Generalizing these results, seismic reflection data can provide insights into the physical state of the shallow plate boundary and help to assess the potential for future shallow rupture in the absence of direct measurements of interplate deformation from most outermost forearc slopes.
Collapse
|
7
|
Martín FA, Pastén D. Complex Networks and the b-Value Relationship Using the Degree Probability Distribution: The Case of Three Mega-Earthquakes in Chile in the Last Decade. ENTROPY 2022; 24:e24030337. [PMID: 35327848 PMCID: PMC8947255 DOI: 10.3390/e24030337] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Revised: 02/09/2022] [Accepted: 02/16/2022] [Indexed: 12/10/2022]
Abstract
Studies from complex networks have increased in recent years, and different applications have been utilized in geophysics. Seismicity represents a complex and dynamic system that has open questions related to earthquake occurrence. In this work, we carry out an analysis to understand the physical interpretation of two metrics of complex systems: the slope of the probability distribution of connectivity (γ) and the betweenness centrality (BC). To conduct this study, we use seismic datasets recorded from three large earthquakes that occurred in Chile: the Mw8.2 Iquique earthquake (2014), the Mw8.4 Illapel earthquake (2015) and the Mw8.8 Cauquenes earthquake (2010). We find a linear relationship between the b−value and the γ value, with an interesting finding about the ratio between the b−value and γ that gives a value of ∼0.4. We also explore a possible physical meaning of the BC. As a first result, we find that the behaviour of this metric is not the same for the three large earthquakes, and it seems that this metric is not related to the b−value and coupling of the zone. We present the first results about the physical meaning of metrics from complex networks in seismicity. These first results are promising, and we hope to be able to carry out further analyses to understand the physics that these complex network parameters represent in a seismic system.
Collapse
|
8
|
Shao Z, Wang W, Liu Q, Pan Z, Liu X, Wang P, Wei W, Feng W, Yin X. Prospects of earthquake physical forecasting under the framework of active-tectonic block theory. CHINESE SCIENCE BULLETIN-CHINESE 2021. [DOI: 10.1360/tb-2021-0968] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
9
|
González G, Pasten-Araya F, Victor P, González Y, Valenzuela J, Shrivastava M. The role of interplate locking on the seismic reactivation of upper plate faults on the subduction margin of northern Chile. Sci Rep 2021; 11:21444. [PMID: 34728693 PMCID: PMC8563723 DOI: 10.1038/s41598-021-00875-6] [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: 03/07/2021] [Accepted: 10/19/2021] [Indexed: 11/30/2022] Open
Abstract
Quaternary deformation in the northern Chile forearc is controlled by trench parallel shortening along reactivated Mesozoic faults. Dextral strikes-slip is expressed in NW–SE striking faults of the Atacama Fault System, and reverse displacement dominates in E–W faults. This deformation results of the convergence in a concave-seaward continental margin. On September 11th, 2020, a Mw 6.3 earthquake and its subsequent aftershocks took place in the coastal region of northern Chile, revealing the reactivation of the deepest segment of a WNW–ESE striking upper plate fault. The reactivation of this fault occurred after the Mw 8.1 Iquique earthquake, and it seems to be connected to a N–S interplate locking segmentation of the plate margin, which is clearly shown by the locking pattern before the Iquique earthquake. This poses the question of how heterogeneous locking influences upper plate seismicity and how it relates to trench-parallel shortening.
Collapse
Affiliation(s)
- Gabriel González
- Departamento de Ciencias Geológicas, National Research Center for Integrated Natural Disaster Management, Universidad Católica del Norte, Avenida Angamos 0610, Antofagasta, Chile.
| | - Francisco Pasten-Araya
- Departamento de Geofísica, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Santiago, Chile
| | - Pia Victor
- Helmholtz-Zentrum Potsdam, Deutsches GeoForschungsZentrum (GFZ) Potsdam, 14473, Potsdam, Germany
| | - Yerko González
- Departamento de Ciencias Geológicas, National Research Center for Integrated Natural Disaster Management, Universidad Católica del Norte, Avenida Angamos 0610, Antofagasta, Chile
| | - Jordán Valenzuela
- Programa de Doctorado en Ciencias Mención Geología, Universidad Católica del Norte, Antofagasta, Chile
| | - Mahesh Shrivastava
- Departamento de Ciencias Geológicas, National Research Center for Integrated Natural Disaster Management, Universidad Católica del Norte, Avenida Angamos 0610, Antofagasta, Chile
| |
Collapse
|
10
|
Sippl C, Moreno M, Benavente R. Microseismicity Appears to Outline Highly Coupled Regions on the Central Chile Megathrust. JOURNAL OF GEOPHYSICAL RESEARCH. SOLID EARTH 2021; 126:e2021JB022252. [PMID: 35865107 PMCID: PMC9286039 DOI: 10.1029/2021jb022252] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Revised: 10/14/2021] [Accepted: 10/28/2021] [Indexed: 05/25/2023]
Abstract
We compiled a novel microseismicity catalog for the Central Chile megathrust (29°-35°S), comprising 8,750 earthquakes between April 2014 and December 2018. These events describe a pattern of three trenchward open half-ellipses, consisting of a continuous, coast-parallel seismicity band at 30-45 km depth, and narrow elongated seismicity clusters that protrude to the shallow megathrust and separate largely aseismic regions along strike. To test whether these shapes could outline highly coupled regions ("asperities") on the megathrust, we invert GPS displacement data for interplate locking. The best-fit locking model does not show good correspondence to seismicity, possibly due to lacking resolution. When we prescribe high locking inside the half-ellipses, however, we obtain models with similar data fits that are preferred according to the Bayesian Information Criterion (BIC). We thus propose that seismicity on the Central Chile megathrust may outline three adjacent highly coupled regions, two of them located between the rupture areas of the 2010 Maule and the 2015 Illapel earthquakes, a segment of the Chilean margin that may be in a late interseismic stage of the seismic cycle.
Collapse
Affiliation(s)
- C. Sippl
- Institute of GeophysicsCzech Academy of SciencesPragueCzech Republic
| | - M. Moreno
- Departamento de GeofísicaUniversidad de ConcepciónConcepciónChile
| | - R. Benavente
- Departamento de Ingeniería CivilUniversidad Católica de la Santísima ConcepciónConcepciónChile
- National Research Center for Integrated Natural Disaster Management (CIGIDEN)SantiagoChile
| |
Collapse
|
11
|
Yamashita F, Fukuyama E, Xu S, Kawakata H, Mizoguchi K, Takizawa S. Two end-member earthquake preparations illuminated by foreshock activity on a meter-scale laboratory fault. Nat Commun 2021; 12:4302. [PMID: 34262027 PMCID: PMC8280151 DOI: 10.1038/s41467-021-24625-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Accepted: 06/21/2021] [Indexed: 02/06/2023] Open
Abstract
The preparation process of natural earthquakes is still difficult to quantify and remains a subject of debate even with modern observational techniques. Here, we show that foreshock activity can shed light on understanding the earthquake preparation process based on results of meter-scale rock friction experiments. Experiments were conducted under two different fault surface conditions before each run: less heterogeneous fault without pre-existing gouge and more heterogeneous fault with pre-existing gouge. The results show that fewer foreshocks occurred along the less heterogeneous fault and were driven by preslip; in contrast, more foreshocks with a lower b value occurred along the more heterogeneous fault and showed features of cascade-up. We suggest that the fault surface condition and the stress redistribution caused by the ongoing fault slip mode control the earthquake preparation process, including the behavior of foreshock activity. Our findings imply that foreshock activity can be a key indicator for probing the fault conditions at present and in the future, and therefore useful for assessing earthquake hazard.
Collapse
Affiliation(s)
- Futoshi Yamashita
- National Research Institute for Earth Science and Disaster Resilience, Tsukuba, Japan.
| | - Eiichi Fukuyama
- National Research Institute for Earth Science and Disaster Resilience, Tsukuba, Japan
- Department of Civil and Earth Resources Engineering, Kyoto University, Kyoto, Japan
| | - Shiqing Xu
- National Research Institute for Earth Science and Disaster Resilience, Tsukuba, Japan
- Department of Earth and Space Sciences, Southern University of Science and Technology, Shenzhen, China
| | - Hironori Kawakata
- National Research Institute for Earth Science and Disaster Resilience, Tsukuba, Japan
- College of Science and Engineering, Ritsumeikan University, Kusatsu, Japan
| | - Kazuo Mizoguchi
- National Research Institute for Earth Science and Disaster Resilience, Tsukuba, Japan
- Central Research Institute of Electric Power Industry, Abiko, Japan
| | - Shigeru Takizawa
- National Research Institute for Earth Science and Disaster Resilience, Tsukuba, Japan
| |
Collapse
|
12
|
Tsunami detection by GPS-derived ionospheric total electron content. Sci Rep 2021; 11:12978. [PMID: 34155312 PMCID: PMC8217264 DOI: 10.1038/s41598-021-92479-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Accepted: 06/04/2021] [Indexed: 02/05/2023] Open
Abstract
To unravel the relationship between earthquake and tsunami using ionospheric total electron content (TEC) changes, we analyzed two Chilean tsunamigenic subduction earthquakes: the 2014 Pisagua Mw 8.1 and the 2015 Illapel Mw 8.3. During the Pisagua earthquake, the TEC changes were detected at the GPS sites located to the north and south of the earthquake epicenter, whereas during the Illapel earthquake, we registered the changes only in the northward direction. Tide-gauge sites mimicked the propagation direction of tsunami waves similar to the TEC change pattern during both earthquakes. The TEC changes were represented by three signals. The initial weaker signal correlated well with Acoustic Rayleigh wave (AWRayleigh), while the following stronger perturbation was interpreted to be caused by Acoustic Gravity wave (AGWepi) and Internal Gravity wave (IGWtsuna) induced by earthquakes and subsequent tsunamis respectively. Inevitably, TEC changes can be utilized to evaluate earthquake occurrence and tsunami propagation within a framework of multi-parameter early warning systems.
Collapse
|
13
|
Caballero E, Chounet A, Duputel Z, Jara J, Twardzik C, Jolivet R. Seismic and Aseismic Fault Slip During the Initiation Phase of the 2017 M W = 6.9 Valparaíso Earthquake. GEOPHYSICAL RESEARCH LETTERS 2021; 48:e2020GL091916. [PMID: 33867597 PMCID: PMC8047919 DOI: 10.1029/2020gl091916] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Revised: 01/25/2021] [Accepted: 01/28/2021] [Indexed: 06/12/2023]
Abstract
Transient deformation associated with foreshocks activity has been observed before large earthquakes, suggesting the occurrence of a detectable preseismic slow slip during the initiation phase. A critical issue consists in discriminating the relative contributions from seismic and aseismic fault slip during the preparation phase of large earthquakes. We focus on the April-May 2017 Valparaíso earthquake sequence, which involved a M W = 6.9 earthquake preceded by intense foreshock activity. To assess the relative contribution of seismic and aseismic slip, we compare surface displacement predicted from foreshocks source models with transient motion measured prior to the mainshock. The comparison between observed and predicted displacements shows that only half of the total displacement can be explained by the contribution of foreshocks. This result suggests the presence of aseismic pre-slip during an initiation phase preceding the mainshock.
Collapse
Affiliation(s)
- Emmanuel Caballero
- Institut Terre et Environnement de Strasbourg (UMR 7063)Université de Strasbourg/EOSTCNRSStrasbourgFrance
| | - Agnès Chounet
- Institut Terre et Environnement de Strasbourg (UMR 7063)Université de Strasbourg/EOSTCNRSStrasbourgFrance
| | - Zacharie Duputel
- Institut Terre et Environnement de Strasbourg (UMR 7063)Université de Strasbourg/EOSTCNRSStrasbourgFrance
| | - Jorge Jara
- Laboratoire de Géologie, Département de GéosciencesCNRS UMR 8538École Normale SupérieurePSL UniversityParisFranceFrance
| | - Cedric Twardzik
- Institut Terre et Environnement de Strasbourg (UMR 7063)Université de Strasbourg/EOSTCNRSStrasbourgFrance
| | - Romain Jolivet
- Laboratoire de Géologie, Département de GéosciencesCNRS UMR 8538École Normale SupérieurePSL UniversityParisFranceFrance
- Institut Universitaire de FranceParisFrance
| |
Collapse
|
14
|
Papadopoulos GA, Agalos A, Minadakis G, Triantafyllou I, Krassakis P. Short-Term Foreshocks as Key Information for Mainshock Timing and Rupture: The M w6.8 25 October 2018 Zakynthos Earthquake, Hellenic Subduction Zone. SENSORS (BASEL, SWITZERLAND) 2020; 20:E5681. [PMID: 33028009 PMCID: PMC7583035 DOI: 10.3390/s20195681] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Revised: 09/26/2020] [Accepted: 09/30/2020] [Indexed: 11/16/2022]
Abstract
Significant seismicity anomalies preceded the 25 October 2018 mainshock (Mw = 6.8), NW Hellenic Arc: a transient intermediate-term (~2 yrs) swarm and a short-term (last 6 months) cluster with typical time-size-space foreshock patterns: activity increase, b-value drop, foreshocks move towards mainshock epicenter. The anomalies were identified with both a standard earthquake catalogue and a catalogue relocated with the Non-Linear Location (NLLoc) algorithm. Teleseismic P-waveforms inversion showed oblique-slip rupture with strike 10°, dip 24°, length ~70 km, faulting depth ~24 km, velocity 3.2 km/s, duration 18 s, slip 1.8 m within the asperity, seismic moment 2.0 × 1026 dyne*cm. The two largest imminent foreshocks (Mw = 4.1, Mw = 4.8) occurred very close to the mainshock hypocenter. The asperity bounded up-dip by the foreshocks area and at the north by the foreshocks/swarm area. The accelerated foreshocks very likely promoted slip accumulation contributing to unlocking the asperity and breaking with the mainshock. The rupture initially propagated northwards, but after 6 s stopped at the north bound and turned southwards. Most early aftershocks concentrated in the foreshocks/swarm area. This distribution was controlled not only by stress transfer from the mainshock but also by pre-existing stress. In the frame of a program for regular monitoring and near real-time identification of seismicity anomalies, foreshock patterns would be detectable at least three months prior the mainshock, thus demonstrating the significant predictive value of foreshocks.
Collapse
Affiliation(s)
| | - Apostolos Agalos
- International Society for the Prevention & Mitigation of Natural Hazards, 10681 Athens, Greece;
| | - George Minadakis
- Department of Bioinformatics, The Cyprus Institute of Neurology & Genetics, 6 International Airport Avenue, Nicosia 2370, P.O. Box 23462, Nicosia 1683, Cyprus;
- The Cyprus School of Molecular Medicine, The Cyprus Institute of Neurology & Genetics, 6 International Airport Avenue, Nicosia 2370, P.O. Box 23462, Nicosia 1683, Cyprus
| | - Ioanna Triantafyllou
- Department of Geology & Geoenvironment, National & Kapodistrian University of Athens, 15784 Athens, Greece;
| | - Pavlos Krassakis
- Centre for Research and Technology, Hellas (CERTH), 52 Egialias Street, 15125 Athens, Greece;
| |
Collapse
|
15
|
Bedford JR, Moreno M, Deng Z, Oncken O, Schurr B, John T, Báez JC, Bevis M. Months-long thousand-kilometre-scale wobbling before great subduction earthquakes. Nature 2020; 580:628-635. [PMID: 32350476 DOI: 10.1038/s41586-020-2212-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Accepted: 02/05/2020] [Indexed: 11/10/2022]
Abstract
Megathrust earthquakes are responsible for some of the most devastating natural disasters1. To better understand the physical mechanisms of earthquake generation, subduction zones worldwide are continuously monitored with geophysical instrumentation. One key strategy is to install stations that record signals from Global Navigation Satellite Systems2,3 (GNSS), enabling us to track the non-steady surface motion of the subducting and overriding plates before, during and after the largest events4-6. Here we use a recently developed trajectory modelling approach7 that is designed to isolate secular tectonic motions from the daily GNSS time series to show that the 2010 Maule, Chile (moment magnitude 8.8) and 2011 Tohoku-oki, Japan (moment magnitude 9.0) earthquakes were preceded by reversals of 4-8 millimetres in surface displacement that lasted several months and spanned thousands of kilometres. Modelling of the surface displacement reversal that occurred before the Tohoku-oki earthquake suggests an initial slow slip followed by a sudden pulldown of the Philippine Sea slab so rapid that it caused a viscoelastic rebound across the whole of Japan. Therefore, to understand better when large earthquakes are imminent, we must consider not only the evolution of plate interface frictional processes but also the dynamic boundary conditions from deeper subduction processes, such as sudden densification of metastable slab.
Collapse
Affiliation(s)
- Jonathan R Bedford
- Helmholtz Centre Potsdam, GFZ German Research Centre for Geosciences, Potsdam, Germany.
| | - Marcos Moreno
- Departamento de Geofísica, Universidad de Concepción, Concepción, Chile
| | - Zhiguo Deng
- Helmholtz Centre Potsdam, GFZ German Research Centre for Geosciences, Potsdam, Germany
| | - Onno Oncken
- Helmholtz Centre Potsdam, GFZ German Research Centre for Geosciences, Potsdam, Germany.,Institute of Geological Sciences, Freie Universität Berlin, Berlin, Germany
| | - Bernd Schurr
- Helmholtz Centre Potsdam, GFZ German Research Centre for Geosciences, Potsdam, Germany
| | - Timm John
- Institute of Geological Sciences, Freie Universität Berlin, Berlin, Germany
| | - Juan Carlos Báez
- University of Chile, National Seismological Centre, Santiago, Chile
| | - Michael Bevis
- School of Earth Sciences, Ohio State University, Columbus, OH, USA
| |
Collapse
|
16
|
Shrivastava MN, González G, Moreno M, Soto H, Schurr B, Salazar P, Báez JC. Earthquake segmentation in northern Chile correlates with curved plate geometry. Sci Rep 2019; 9:4403. [PMID: 30867445 PMCID: PMC6416342 DOI: 10.1038/s41598-019-40282-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Accepted: 01/24/2019] [Indexed: 12/04/2022] Open
Abstract
We performed an integrated analysis of the coseismic slip, afterslip and aftershock activity of the 2014 Mw 8.1 Pisagua earthquake. This earthquake seems to be spatially located between two major historical earthquakes, the 1868 Mw 8.8 earthquake in southern Peru and the 1877 Mw 8.5 earthquake in northern Chile. Continuous GPS data were used to model the coseismic slip of the mainshock and the largest aftershock (Mw 7.6). The afterslip was modeled for 273 days (end of year 2014) after the largest aftershock, revealing two patches of afterslip: a southern patch between the mainshock and the largest aftershock and a patch to the north of the mainshock. Observations from the seismic network indicate that aftershocks were concentrated near the southern patch. Conversely, the northern patch contained hardly any aftershocks, indicating a dominant aseismic slip. The Pisagua earthquake occurred within a prominent, curved section of the Andean subduction zone. This section may have acted as a barrier for the largest historical earthquakes and as an isolated segment during the Pisagua earthquake.
Collapse
Affiliation(s)
- Mahesh N Shrivastava
- National Research Center for Integrated Natural Disaster Management, Santiago, Chile. .,Departamento de Ciencias Geológicas, Universidad Católica del Norte, Antofagasta, Chile.
| | - Gabriel González
- National Research Center for Integrated Natural Disaster Management, Santiago, Chile.,Departamento de Ciencias Geológicas, Universidad Católica del Norte, Antofagasta, Chile
| | - Marcos Moreno
- GFZ Helmholtz Centre Potsdam, German Research Centre for Geosciences, Potsdam, Germany.,Departamento de Geofísica, Universidad de Concepción, Concepción, Chile
| | - Hugo Soto
- GFZ Helmholtz Centre Potsdam, German Research Centre for Geosciences, Potsdam, Germany
| | - Bernd Schurr
- GFZ Helmholtz Centre Potsdam, German Research Centre for Geosciences, Potsdam, Germany
| | - Pablo Salazar
- National Research Center for Integrated Natural Disaster Management, Santiago, Chile.,Departamento de Ciencias Geológicas, Universidad Católica del Norte, Antofagasta, Chile
| | - Juan Carlos Báez
- Centro Sismológico Nacional, Universidad de Chile, Santiago, Chile
| |
Collapse
|
17
|
Audit of stored strain energy and extent of future earthquake rupture in central Himalaya. Sci Rep 2018; 8:16697. [PMID: 30420673 PMCID: PMC6232156 DOI: 10.1038/s41598-018-35025-y] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Accepted: 10/26/2018] [Indexed: 11/30/2022] Open
Abstract
The deadly 25 April 2015 Gorkha earthquake (Mw = 7.8) and aftershocks have partially released the accumulated interseismic strain along the Main Himalayan Thrust (MHT). Postseismic deformation associated with this earthquake is mainly confined to the north of the rupture. This suggests possible occurrence of future large events towards west or south, where MHT is locked. Asperities arising due to heterogeneity in the stress-strain patterns are believed to play a major role in controlling the coseismic rupture propagation. We determine interseismic coupling along the MHT and spatial variations in total strain rate using two decades of GPS, InSAR and sprit leveling data. Further, b-values derived from the seismicity data are used to identify zones of stress accumulation. We demonstrate that the 2015 earthquake ruptured an asperity which hosted high strain and stress accumulation prior to the event. A similar asperity towards west of the epicenter with unreleased strain energy is identified. This could spawn a future large earthquake akin in magnitude to the 2015 Gorkha event. These findings compel a revisit of the seismic hazard assessment of the central Himalaya.
Collapse
|
18
|
Microearthquakes preceding a M4.2 Earthquake Offshore Istanbul. Sci Rep 2018; 8:16176. [PMID: 30385791 PMCID: PMC6212396 DOI: 10.1038/s41598-018-34563-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Accepted: 10/19/2018] [Indexed: 11/24/2022] Open
Abstract
A primary hurdle in observing small foreshocks is the detection-limit of most seismic networks, which is typically about magnitude M1-1.5. We show that a start-up test of a borehole-based seismic network with a much lower detection limit overcame this problem for an Mw4.2 earthquake. This earthquake occurred offshore of Istanbul, Turkey, on a fault system that is likely to rupture in an M > 7 event in the coming decades. In the three days before and two after, a total of 62 or more earthquakes, including at least 18 foreshocks, came from the mainshock source area. The signal similarity of the foreshocks shows a clear increase during the hours before the Mw4.2 mainshock. Similar foreshock sequences have recently been reported for a few well monitored M > 7 plate-boundary earthquakes. The sequence surrounding the Mw4.2 gives the impression of stochastic failures that ended up interactively unloading stress concentrations. The Mw4.2 mainshock then resulted from the accumulated release of significantly smaller events, as suggested by other field and laboratory studies.
Collapse
|
19
|
Khoshmanesh M, Shirzaei M. Episodic creep events on the San Andreas Fault caused by pore-pressure variations. NATURE GEOSCIENCE 2018; 11:610-614. [PMID: 29937919 PMCID: PMC6008793 DOI: 10.1038/s41561-018-0160-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Accepted: 05/18/2018] [Indexed: 06/08/2023]
Abstract
Recent seismic and geodetic observations indicate that interseismic creep rate varies in both time and space. The spatial extent of creep pinpoints locked asperities, while its temporary accelerations, known as slow-slip events, may trigger earthquakes. Although the conditions promoting fault creep are well-studied, the mechanisms for initiating episodic slow-slip events are enigmatic. Here we investigate surface deformation measured by radar interferometry along the central San Andreas Fault between 2003 and 2010 to constrain the temporal evolution of creep. We show that slow-slip events are ensembles of localized creep bursts that aseismically rupture isolated fault compartments. Using a rate and state friction model, we show that effective normal stress is temporally variable on the fault, and support this using seismic observations. We propose that, compaction-driven elevated pore fluid pressure in hydraulically isolated fault zone and subsequent frictional dilation cause the observed slow slip episodes. We further suggest that the 2004 Mw6 Parkfield earthquake might have been triggered by a slow-slip event, which increased the Coulomb failure stress by up to 0.45 bar per year. This implies that while creeping segments are suggested to act as seismic rupture barriers, slow-slip events on these zones might promote seismicity on adjacent locked segments.
Collapse
Affiliation(s)
- Mostafa Khoshmanesh
- School of Earth and Space Exploration, Arizona State University, Tempe, AZ, USA
| | - Manoochehr Shirzaei
- School of Earth and Space Exploration, Arizona State University, Tempe, AZ, USA
| |
Collapse
|
20
|
The Consideration of Formal Errors in Spatiotemporal Filtering Using Principal Component Analysis for Regional GNSS Position Time Series. REMOTE SENSING 2018. [DOI: 10.3390/rs10040534] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
|
21
|
Calibrating coseismic coastal land-level changes during the 2014 Iquique (Mw=8.2) earthquake (northern Chile) with leveling, GPS and intertidal biota. PLoS One 2017; 12:e0174348. [PMID: 28333998 PMCID: PMC5363922 DOI: 10.1371/journal.pone.0174348] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Accepted: 03/07/2017] [Indexed: 11/21/2022] Open
Abstract
The April 1st 2014 Iquique earthquake (MW 8.1) occurred along the northern Chile margin where the Nazca plate is subducted below the South American continent. The last great megathrust earthquake here, in 1877 of Mw ~8.8 opened a seismic gap, which was only partly closed by the 2014 earthquake. Prior to the earthquake in 2013, and shortly after it we compared data from leveled benchmarks, deployed campaign GPS instruments, continuous GPS stations and estimated sea levels using the upper vertical level of rocky shore benthic organisms including algae, barnacles, and mussels. Land-level changes estimated from mean elevations of benchmarks indicate subsidence along a ~100-km stretch of coast, ranging from 3 to 9 cm at Corazones (18°30’S) to between 30 and 50 cm at Pisagua (19°30’S). About 15 cm of uplift was measured along the southern part of the rupture at Chanabaya (20°50’S). Land-level changes obtained from benchmarks and campaign GPS were similar at most sites (mean difference 3.7±3.2 cm). Higher differences however, were found between benchmarks and continuous GPS (mean difference 8.5±3.6 cm), possibly because sites were not collocated and separated by several kilometers. Subsidence estimated from the upper limits of intertidal fauna at Pisagua ranged between 40 to 60 cm, in general agreement with benchmarks and GPS. At Chanavaya, the magnitude and sense of displacement of the upper marine limit was variable across species, possibly due to species—dependent differences in ecology. Among the studied species, measurements on lithothamnioid calcareous algae most closely matched those made with benchmarks and GPS. When properly calibrated, rocky shore benthic species may be used to accurately measure land-level changes along coasts affected by subduction earthquakes. Our calibration of those methods will improve their accuracy when applied to coasts lacking pre-earthquake data and in estimating deformation during pre–instrumental earthquakes.
Collapse
|
22
|
Kato A, Fukuda J, Kumazawa T, Nakagawa S. Accelerated nucleation of the 2014 Iquique, Chile Mw 8.2 Earthquake. Sci Rep 2016; 6:24792. [PMID: 27109362 PMCID: PMC4842989 DOI: 10.1038/srep24792] [Citation(s) in RCA: 71] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Accepted: 04/05/2016] [Indexed: 11/09/2022] Open
Abstract
The earthquake nucleation process has been vigorously investigated based on geophysical observations, laboratory experiments, and theoretical studies; however, a general consensus has yet to be achieved. Here, we studied nucleation process for the 2014 Iquique, Chile Mw 8.2 megathrust earthquake located within the current North Chile seismic gap, by analyzing a long-term earthquake catalog constructed from a cross-correlation detector using continuous seismic data. Accelerations in seismicity, the amount of aseismic slip inferred from repeating earthquakes, and the background seismicity, accompanied by an increasing frequency of earthquake migrations, started around 270 days before the mainshock at locations up-dip of the largest coseismic slip patch. These signals indicate that repetitive sequences of fast and slow slip took place on the plate interface at a transition zone between fully locked and creeping portions. We interpret that these different sliding modes interacted with each other and promoted accelerated unlocking of the plate interface during the nucleation phase.
Collapse
Affiliation(s)
- Aitaro Kato
- Earthquake and Volcano Research Center, Graduate School of Environmental Studies, Nagoya University, Nagoya, Japan, Furo-cho, Chikusa-ku, Nagoya, 464-8601, Japan.,Earthquake Research Institute, University of Tokyo, Tokyo, Japan, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-0032, Japan
| | - Jun'ichi Fukuda
- Earthquake Research Institute, University of Tokyo, Tokyo, Japan, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-0032, Japan
| | - Takao Kumazawa
- The Institute of Statistical Mathematics, Tachikawa, Japan, 10-3 Midori-cho, Tachikawa, Tokyo, 190-8562, Japan
| | - Shigeki Nakagawa
- Earthquake Research Institute, University of Tokyo, Tokyo, Japan, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-0032, Japan
| |
Collapse
|
23
|
Subducting seamounts control interplate coupling and seismic rupture in the 2014 Iquique earthquake area. Nat Commun 2015; 6:8267. [PMID: 26419949 PMCID: PMC4667434 DOI: 10.1038/ncomms9267] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2015] [Accepted: 08/04/2015] [Indexed: 11/13/2022] Open
Abstract
To date, the parameters that determine the rupture area of great subduction zone earthquakes remain contentious. On 1 April 2014, the Mw 8.1 Iquique earthquake ruptured a portion of the well-recognized northern Chile seismic gap but left large highly coupled areas un-ruptured. Marine seismic reflection and swath bathymetric data indicate that structural variations in the subducting Nazca Plate control regional-scale plate-coupling variations, and the limited extent of the 2014 earthquake. Several under-thrusting seamounts correlate to the southward and up-dip arrest of seismic rupture during the 2014 Iquique earthquake, thus supporting a causal link. By fracturing of the overriding plate, the subducting seamounts are likely further responsible for reduced plate-coupling in the shallow subduction zone and in a lowly coupled region around 20.5°S. Our data support that structural variations in the lower plate influence coupling and seismic rupture offshore Northern Chile, whereas the structure of the upper plate plays a minor role. On 1 April 2014 the Mw 8.1 Iquique earthquake seemed to close the well-recognized northern Chile seismic gap, producing only a small rupture. Here, the authors present seismic reflection and multibeam bathymetry data from the area suggesting that seamount subduction played a role in halting the rupture.
Collapse
|
24
|
|