Drilling Into Shallow Interplate Thrust Zone for Understanding of Irregular Rupturing of Megathrust
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Seismic Rate Variations Prior to the 2010 Maule, Chile MW 8.8 Giant Megathrust Earthquake
www.nature.com/scientificreports OPEN Seismic rate variations prior to the 2010 Maule, Chile MW 8.8 giant megathrust earthquake Benoit Derode1*, Raúl Madariaga1,2 & Jaime Campos1 The MW 8.8 Maule earthquake is the largest well-recorded megathrust earthquake reported in South America. It is known to have had very few foreshocks due to its locking degree, and a strong aftershock activity. We analyze seismic activity in the area of the 27 February 2010, MW 8.8 Maule earthquake at diferent time scales from 2000 to 2019. We diferentiate the seismicity located inside the coseismic rupture zone of the main shock from that located in the areas surrounding the rupture zone. Using an original spatial and temporal method of seismic comparison, we fnd that after a period of seismic activity, the rupture zone at the plate interface experienced a long-term seismic quiescence before the main shock. Furthermore, a few days before the main shock, a set of seismic bursts of foreshocks located within the highest coseismic displacement area is observed. We show that after the main shock, the seismic rate decelerates during a period of 3 years, until reaching its initial interseismic value. We conclude that this megathrust earthquake is the consequence of various preparation stages increasing the locking degree at the plate interface and following an irregular pattern of seismic activity at large and short time scales. Giant subduction earthquakes are the result of a long-term stress localization due to the relative movement of two adjacent plates. Before a large earthquake, the interface between plates is locked and concentrates the exter- nal forces, until the rock strength becomes insufcient, initiating the sudden rupture along the plate interface. -
Foreshock Sequences and Short-Term Earthquake Predictability on East Pacific Rise Transform Faults
NATURE 3377—9/3/2005—VBICKNELL—137936 articles Foreshock sequences and short-term earthquake predictability on East Pacific Rise transform faults Jeffrey J. McGuire1, Margaret S. Boettcher2 & Thomas H. Jordan3 1Department of Geology and Geophysics, Woods Hole Oceanographic Institution, and 2MIT-Woods Hole Oceanographic Institution Joint Program, Woods Hole, Massachusetts 02543-1541, USA 3Department of Earth Sciences, University of Southern California, Los Angeles, California 90089-7042, USA ........................................................................................................................................................................................................................... East Pacific Rise transform faults are characterized by high slip rates (more than ten centimetres a year), predominately aseismic slip and maximum earthquake magnitudes of about 6.5. Using recordings from a hydroacoustic array deployed by the National Oceanic and Atmospheric Administration, we show here that East Pacific Rise transform faults also have a low number of aftershocks and high foreshock rates compared to continental strike-slip faults. The high ratio of foreshocks to aftershocks implies that such transform-fault seismicity cannot be explained by seismic triggering models in which there is no fundamental distinction between foreshocks, mainshocks and aftershocks. The foreshock sequences on East Pacific Rise transform faults can be used to predict (retrospectively) earthquakes of magnitude 5.4 or greater, in narrow spatial and temporal windows and with a high probability gain. The predictability of such transform earthquakes is consistent with a model in which slow slip transients trigger earthquakes, enrich their low-frequency radiation and accommodate much of the aseismic plate motion. On average, before large earthquakes occur, local seismicity rates support the inference of slow slip transients, but the subject remains show a significant increase1. In continental regions, where dense controversial23. -
Large Intermediate-Depth Earthquakes and the Subduction Process
80 Physics ofthe Earth and Planetary Interiors, 53 (1988) 80—166 Elsevier Science Publishers By., Amsterdam — Printed in The Netherlands Large intermediate-depth earthquakes and the subduction process Luciana Astiz ~, Thorne Lay 2 and Hiroo Kanamori ~ ‘Seismological Laboratory, California Institute of Technology, Pasadena, CA (U.S.A.) 2 Department of Geological Sciences, University ofMichigan, Ann Arbor, MI (USA.) (Received September 22, 1987; accepted October 21, 1987) Astiz, L., Lay, T. and Kanamori, H., 1988. Large intermediate-depth earthquakes and the subduction process. Phys. Earth Planet. Inter., 53: 80—166. This study provides an overview of intermediate-depth earthquake phenomena, placing emphasis on the larger, tectonically significant events, and exploring the relation of intermediate-depth earthquakes to shallower seismicity. Especially, we examine whether intermediate-depth events reflect the state of interplate coupling at subduction zones. and whether this activity exhibits temporal changes associated with the occurrence of large underthrusting earthquakes. Historic record of large intraplate earthquakes (m B 7.0) in this century shows that the New Hebrides and Tonga subduction zones have the largest number of large intraplate events. Regions associated with bends in the subducted lithosphere also have many large events (e.g. Altiplano and New Ireland). We compiled a catalog of focal mechanisms for events that occurred between 1960 and 1984 with M> 6 and depth between 40 and 200 km. The final catalog includes 335 events with 47 new focal mechanisms, and is probably complete for earthquakes with mB 6.5. For events with M 6.5, nearly 48% of the events had no aftershocks and only 15% of the events had more than five aftershocks within one week of the mainshock. -
The Megathrust Earthquake Cycle
Ocean. A little less than four years later, a similar-sized earthquake strikes the Prince William Sound area of Alaska producing a tsunami that ravages Alaska and the west coast of North America. At the time, it was clear Not My Fault: The megathrust these were very large quakes, registering 8.6 and 8.5 on earthquake cycle the Surface Wave magnitude scale, the variant of the Lori Dengler/For the Times-Standard Richter scale that was in use at the time. But only after Posted: May 24, 2017 theresearch of two more Reid award winners Aki and Kanamori (whose work would replace the Richter scale The Seismological Society of America is the world’s with seismic moment and moment magnitude) would largest organization dedicated to the study of the true size of these earthquakes Become clear. When earthquakes and their impacts on humans. The recalculated in the 70s, 1964 Alaska was upped to 9.2 Society’s highest honor is the Henry F. Reid Award and 1960 Chile Became a whopping 9.5, the largest recognizes the work that has done the most to the magnitude earthquake ever recorded on a seismograph. transform the discipline. This year’s recipient is George Plafker for his studies of great suBduction zone Both of these earthquakes occurred before plate earthquakes. tectonics, the grand unifying theory of how the outer part of the earth works, was well known or accepted. In I mentioned Dr. Plafker in my last column as a pioneer of the sixties, many earth scientists Believed great post earthquake/tsunami reconnaissance. -
Fully-Coupled Simulations of Megathrust Earthquakes and Tsunamis in the Japan Trench, Nankai Trough, and Cascadia Subduction Zone
Noname manuscript No. (will be inserted by the editor) Fully-coupled simulations of megathrust earthquakes and tsunamis in the Japan Trench, Nankai Trough, and Cascadia Subduction Zone Gabriel C. Lotto · Tamara N. Jeppson · Eric M. Dunham Abstract Subduction zone earthquakes can pro- strate that horizontal seafloor displacement is a duce significant seafloor deformation and devas- major contributor to tsunami generation in all sub- tating tsunamis. Real subduction zones display re- duction zones studied. We document how the non- markable diversity in fault geometry and struc- hydrostatic response of the ocean at short wave- ture, and accordingly exhibit a variety of styles lengths smooths the initial tsunami source relative of earthquake rupture and tsunamigenic behavior. to commonly used approach for setting tsunami We perform fully-coupled earthquake and tsunami initial conditions. Finally, we determine self-consistent simulations for three subduction zones: the Japan tsunami initial conditions by isolating tsunami waves Trench, the Nankai Trough, and the Cascadia Sub- from seismic and acoustic waves at a final sim- duction Zone. We use data from seismic surveys, ulation time and backpropagating them to their drilling expeditions, and laboratory experiments initial state using an adjoint method. We find no to construct detailed 2D models of the subduc- evidence to support claims that horizontal momen- tion zones with realistic geometry, structure, fric- tum transfer from the solid Earth to the ocean is tion, and prestress. Greater prestress and rate-and- important in tsunami generation. state friction parameters that are more velocity- weakening generally lead to enhanced slip, seafloor Keywords tsunami; megathrust earthquake; deformation, and tsunami amplitude. -
Coseismic Slip Model of Offshore Moderate Interplate Earthquakes on March 9, 2011 in Tohoku Using Tsunami Waveforms Tatsuya Kubo
1 Coseismic slip model of offshore moderate interplate earthquakes on March 9, 2 2011 in Tohoku using tsunami waveforms 3 Tatsuya Kubotaa*Ryota Hinoa, Daisuke Inazub1, Yoshihiro Itoc, Takeshi Iinumad, 4 Yusaku Ohtaa, Syuichi Suzukia, Kensuke Suzukid 5 a Graduate School of Science, Tohoku University, 6-6, Aza-Aoba, Aramaki, Aoba-ku, 6 Sendai 980-8578, Japan. 7 bU Tokyo Ocean Alliance, The University of Tokyo, Tokyo, Japan. 8 cDisaster Prevention Research Institute, Kyoto University, Uji, Japan. 9 dJapan Agency for Marine-Earth Science and Technology, Yokohama, Japan. 10 1Present address: Department of Ocean Sciences, Tokyo University of Marine Science 11 and Technology, Tokyo, Japan. 12 13 E-mail addresses: 14 Tatsuya Kubota: [email protected] 15 Ryota Hino: [email protected] 16 Daisuke Inazu: [email protected] 17 (Present e-mail address: [email protected]) 18 Yoshihiro Ito: [email protected] 19 Takeshi Iinuma: [email protected] 20 Yusaku Ohta: [email protected] 21 Syuichi Suzuki: [email protected] 22 Kensuke Suzuki: [email protected] 23 *Corresponding author E-mail: [email protected] 1 24 25 Abstract 26 We estimated the coseismic slip distribution associated with the Mw 7.2 and 6.5 27 foreshocks of the 2011 Tohoku-Oki earthquake based on analysis of the tsunami 28 waveform records obtained just above their focal areas. The results show that the main 29 rupture areas of each of the foreshocks do not overlap with each other, and show a 30 distribution that is complementary to the postseismic slip area of the first Mw 7.2 31 foreshock as well as to the epicenters of smaller earthquakes during foreshock activity. -
Presence of Interplate Channel Layer Controls of Slip During and After The
www.nature.com/scientificreports OPEN Presence of interplate channel layer controls of slip during and after the 2011 Tohoku‑Oki earthquake through the frictional characteristics Ryoko Nakata1*, Takane Hori2, Seiichi Miura3 & Ryota Hino1 There are signifcant diferences between the middle and southern segments of the Japan Trench in terms of the seismic and aseismic slips on the plate interface and seismic velocity structures. Although the large coseismic slip of the 2011 Tohoku‑Oki earthquake was limited to the middle segment, the observed negative residual gravity anomaly area in the southern segment corresponds to the postseismic slip area of the Tohoku‑Oki earthquake. A density distribution model can explain the diferent slip behaviours of the two segments by considering their structural diferences. The model indicates that the plate interface in the south was covered with a thick channel layer, as indicated by seismic survey imaging, and this layer resulted in a residual gravity anomaly. Numerical simulations which assumed evident frictional heterogeneity caused by the layer in the south efciently reproduced M9 earthquakes recurring only in the middle, followed by evident postseismic slips in the south. This study proposes that although the layer makes the megathrust less compliant to seismic slip, it promotes aseismic slips following the growth of seismic slips on the fault in an adjacent region. Many studies which investigated the spatiotemporal distributions of various seismic and geodetic events and underground structures have demonstrated that there are conspicuous diferences between the middle and southern segments of the Japan Trench. Te shallow area of the coast of Fukushima Prefecture, i.e. -
A Possible Restart of an Interplate Slow Slip Adjacent to the Tokai Seismic Gap in Japan Shinzaburo Ozawa*, Mikio Tobita and Hiroshi Yarai
Ozawa et al. Earth, Planets and Space (2016) 68:54 DOI 10.1186/s40623-016-0430-4 FULL PAPER Open Access A possible restart of an interplate slow slip adjacent to the Tokai seismic gap in Japan Shinzaburo Ozawa*, Mikio Tobita and Hiroshi Yarai Abstract The Tokai region of Japan is known to be a seismic gap area and is expected to be the source region of the antici- pated Tokai earthquake with a moment magnitude of over 8. Interplate slow slip occurred from approximately 2001 and subsided in 2005 in the area adjacent to the source region of the expected Tokai earthquake. Eight years later, the Tokai region again revealed signs of a slow slip from early 2013. This is the first evidence based on a dense Global Positioning System network that Tokai long-term slow slips repeatedly occur. Two datasets with different detrending produce similar transient crustal deformation and aseismic slip models, supporting the occurrence of the Tokai slow slip. The center of the current Tokai slow slip is near Lake Hamana, south of the center of the previous Tokai slow slip. The estimated moments, which increase at a roughly constant rate, amount to that of an earthquake with a moment magnitude of 6.6. If the ongoing Tokai slow slip subsides soon, it will suggest that there are at least two different types of slow slip events in the Tokai long-term slow slip area: that is, a large slow slip with a moment magnitude of over 7 with undulating time evolution and a small one with a moment magnitude of around 6.6 with a roughly linear time evolution. -
Crustal Faults in the Chilean Andes: Geological Constraints and Seismic Potential
Andean Geology 46 (1): 32-65. January, 2019 Andean Geology doi: 10.5027/andgeoV46n1-3067 www.andeangeology.cl Crustal faults in the Chilean Andes: geological constraints and seismic potential *Isabel Santibáñez1, José Cembrano2, Tiaren García-Pérez1, Carlos Costa3, Gonzalo Yáñez2, Carlos Marquardt4, Gloria Arancibia2, Gabriel González5 1 Programa de Doctorado en Ciencias de la Ingeniería, Pontificia Universidad Católica de Chile, Avda. Vicuña Mackenna 4860, Macul, Santiago, Chile. [email protected]; [email protected] 2 Departamento de Ingeniería Estructural y Geotécnica, Pontificia Universidad Católica de Chile, Avda. Vicuña Mackenna 4860, Macul, Santiago, Chile. [email protected]; [email protected]; [email protected] 3 Departamento de Geología, Universidad de San Luis, Ejercito de Los Andes 950, D5700HHW San Luis, Argentina. [email protected] 4 Departamento de Ingeniería Estructural y Geotécnica y Departamento de Ingeniería de Minería, Pontificia Universidad Católica de Chile. Avda. Vicuña Mackenna 4860, Macul, Santiago, Chile. [email protected] 5 Departamento de Ciencias Geológicas, Universidad Católica del Norte, Angamos 0610, Antofagasta, Chile. [email protected] * Corresponding author: [email protected] ABSTRACT. The Chilean Andes, as a characteristic tectonic and geomorphological region, is a perfect location to unravel the geologic nature of seismic hazards. The Chilean segment of the Nazca-South American subduction zone has experienced mega-earthquakes with Moment Magnitudes (Mw) >8.5 (e.g., Mw 9.5 Valdivia, 1960; Mw 8.8 Maule, 2010) and many large earthquakes with Mw >7.5, both with recurrence times of tens to hundreds of years. By contrast, crustal faults within the overriding South American plate commonly have longer recurrence times (thousands of years) and are known to produce earthquakes with maximum Mw of 7.0 to 7.5. -
Fault Stressing in the Overriding Plate Due to Megathrust Coupling Along the Nankai Trough, Japan
EGU2020-18393 https://doi.org/10.5194/egusphere-egu2020-18393 EGU General Assembly 2020 © Author(s) 2021. This work is distributed under the Creative Commons Attribution 4.0 License. Fault stressing in the overriding plate due to megathrust coupling along the Nankai trough, Japan Akinori Hashima1, Hiroshi Sato1, Tatsuya Ishiyama1, Andrew Freed2, and Thorsten Becker3 1Earthquake Research Institute, University of Tokyo, Tokyo, Japan 2Department of Earth, Atmospheric, and Planetary Sciences, Purdue University, West Lafayette, USA 3Jackson School of Geosciences, The University of Texas at Austin, Austin, USA The Nankai trough has hosted ~M8 interplate earthquakes with the interval of 100-200 years. The crustal activity in southwest (SW) Japan in the overriding plate was relatively quiet after the last coupled megathrust ruptures occurred in 1944 and 1946. In the recent 20 years, however, SW Japan has experienced ~M7 earthquakes such as the 2016 Kumamoto earthquake. Similar activation of crustal earthquakes in the later stage of the megathrust earthquake cycles can be found in the historical earthquake occurrence based on paleographical studies. Such a change cannot be resolved by the probabilistic approaches, which usually rely on paleo-seismological data on longer timescales. Here, we show a deterministic way to quantify the current stressing state on the source faults due to megathrust coupling at the Nankai trough, making use of the data captured by the dense, modern geodetic network in Japan. We constructed a 3-D finite element model (FEM) around the Japanese islands including the viscoelastic feature in the asthenosphere. The geometry of plate boundary on the Philippine Sea slab is based on earthquake distributions determined by the previous studies. -
Repeated Occurrence of Surface-Sediment Remobilization
Ikehara et al. Earth, Planets and Space (2020) 72:114 https://doi.org/10.1186/s40623-020-01241-y FULL PAPER Open Access Repeated occurrence of surface-sediment remobilization along the landward slope of the Japan Trench by great earthquakes Ken Ikehara1* , Kazuko Usami1,2 and Toshiya Kanamatsu3 Abstract Deep-sea turbidites have been utilized to understand the history of past large earthquakes. Surface-sediment remo- bilization is considered to be a mechanism for the initiation of earthquake-induced turbidity currents, based on the studies on the event deposits formed by recent great earthquakes, such as the 2011 Tohoku-oki earthquake, although submarine slope failure has been considered to be a major contributor. However, it is still unclear that the surface-sed- iment remobilization has actually occurred in past great earthquakes. We examined a sediment core recovered from the mid-slope terrace (MST) along the Japan Trench to fnd evidence of past earthquake-induced surface-sediment remobilization. Coupled radiocarbon dates for turbidite and hemipelagic muds in the core show small age diferences (less than a few 100 years) and suggest that initiation of turbidity currents caused by the earthquake-induced surface- sediment remobilization has occurred repeatedly during the last 2300 years. On the other hand, two turbidites among the examined 11 turbidites show relatively large age diferences (~ 5000 years) that indicate the occurrence of large sea-foor disturbances such as submarine slope failures. The sedimentological (i.e., of diatomaceous nature and high sedimentation rates) and tectonic (i.e., continuous subsidence and isolated small basins) settings of the MST sedimentary basins provide favorable conditions for the repeated initiation of turbidity currents and for deposition and preservation of fne-grained turbidites. -
Distribution of Discrete Seismic Asperities and Aseismic Slip Along the Ecuadorian Megathrust ∗ M
Earth and Planetary Science Letters 400 (2014) 292–301 Contents lists available at ScienceDirect Earth and Planetary Science Letters www.elsevier.com/locate/epsl Distribution of discrete seismic asperities and aseismic slip along the Ecuadorian megathrust ∗ M. Chlieh a, , P.A. Mothes b, J.-M. Nocquet a, P. Jarrin b, P. Charvis a, D. Cisneros c, Y. Font a, J.-Y. Collot a, J.-C. Villegas-Lanza d, F. Rolandone e, M. Vallée f, M. Regnier a, M. Segovia b, X. Martin a, H. Yepes b a Géoazur, Université Nice Sophia Antipolis, IRD, CNRS, OCA, Nice, France b Instituto Geofísico, Escuela Politécnica Nacional, Quito, Ecuador c Instituto Geográfico Militar, Quito, Ecuador d Instituto Geofísico del Perú, Lima, Peru e Université Pierre et Marie Curie, Paris, France f Institut de Physique du Globe de Paris, Sorbonne Paris Cité, Univ. Paris Diderot, UMR 7154 CNRS, 75005 Paris, France a r t i c l e i n f o a b s t r a c t Article history: A dense GPS network deployed in Ecuador reveals a highly heterogeneous pattern of interseismic Received 16 January 2014 coupling confined in the first 35 km depth of the contact between the subducting oceanic Nazca Received in revised form 11 May 2014 plate and the North Andean Sliver. Interseismic models indicate that the coupling is weak and very Accepted 14 May 2014 shallow (0–15 km) in south Ecuador and increases northward, with maximum found in the rupture Available online xxxx areas of large (Mw > 7.0) megathrust earthquakes that occurred during the 20th century.