Siesmic Activity and Its Periphery
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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. -
Temporal and Spatial Evolution Analysis of Earthquake Events in California and Nevada Based on Spatial Statistics
International Journal of Geo-Information Article Temporal and Spatial Evolution Analysis of Earthquake Events in California and Nevada Based on Spatial Statistics Weifeng Shan 1,2 , Zhihao Wang 2, Yuntian Teng 1,* and Maofa Wang 3 1 Institute of Geophysics, China Earthquake Administration, Beijing 100081, China; [email protected] 2 School of Emergency Management, Institute of Disaster Prevention, Langfang 065201, China; [email protected] 3 School of Computer and Information Security, Guilin University of Electronic Science and Technology, Guilin 541004, China; [email protected] * Correspondence: [email protected] Abstract: Studying the temporal and spatial evolution trends in earthquakes in an area is beneficial for determining the earthquake risk of the area so that local governments can make the correct decisions for disaster prevention and reduction. In this paper, we propose a new method for analyzing the temporal and spatial evolution trends in earthquakes based on earthquakes of magnitude 3.0 or above from 1980 to 2019 in California and Nevada. The experiment’s results show that (1) the frequency of earthquake events of magnitude 4.5 or above present a relatively regular change trend of decreasing–rising in this area; (2) by using the weighted average center method to analyze the spatial concentration of earthquake events of magnitude 3.0 or above in this region, we find that the weighted average center of the earthquake events in this area shows a conch-type movement law, where it moves closer to the center from all sides; (3) the direction of the spatial distribution of earthquake events in this area shows a NW–SE pattern when the standard deviational ellipse (SDE) Citation: Shan, W.; Wang, Z.; Teng, method is used, which is basically consistent with the direction of the San Andreas Fault Zone across Y.; Wang, M. -
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. -
Drilling Into Shallow Interplate Thrust Zone for Understanding of Irregular Rupturing of Megathrust
Drilling into shallow interplate thrust zone for understanding of irregular rupturing of megathrust Ryota Hino (Tohoku University) * abstract It is generally conceived that the shallowest portion of the megathrsut fault is completely aseismic and allow stable sliding during the interseismic period. However, anomalous tsunami earthquakes sporadically happen in this area, causing disproportionally large tsunami as compared to the radiated seismic energy, release large displacement at the plate boundary. It has not been well understood why and how such the anomalous earthquake occurs irregularly. Also in the rupture propagation of gigantic (M>9) earthquakes involving simultaneous rupturing of multiple asperities, the aseismic plate boundary seems to play an important role. Therefore, the mechanical properties of the most trenchward zone of the subudction plate boundary are very important for understanding mechanisms generating catastrophic earthquakes. I propose here to make long-term monitoring in deep boreholes drilled the shallowest portion of the megathrust fault to clarify how deform this area in the interseismic period. Downhole logging and seismic profiling will provide the answer to the cause of the anomalous rupture process by revealing the internal structure of the fault zone. * Research center for prediction of earthquakes and volcanic eruption Graduate School of Science, Tohoku University [email protected] 1. Introduction The occurrence of the 2004 Sumatra-Andaman earthquake (M9.1) showed that an interplate earthquake which ruptures almost entire part of a subduction system can occur, although we only know recurrence history of thrust earthquakes with sizes of M~8 in the system. Recent paleoseismological studies have revealed the occurrence of gigathrust earthquakes, much larger than M8 class megathrust earthquakes, in other subduction zones where only megathrust earthquakes have been known to occur. -
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. -
Earthquakes Mechanics and Effects
Earthquakes Mechanics and Effects Instructional Material Complementing FEMA 451, Design Examples Earthquake Mechanics 2 - 1 This topic explains: 1. The physical mechanisms of an earthquake, plate tectonics, the various types of faults, the earthquake source, path and site elements, and the terminology used to describe the location, severity, and frequency of an earthquake and maps of its physical effects in earthquake-prone areas of the nation and 2. The use of geology, seismicity, and paleoseismicity to determine magnitude as a measure of the “size” of an earthquake and the intensity as the damage state of buildings from ground shaking and ground failure. References are: Bolt, B. 1999. Earthquakes, 4th Ed. New York, New York: W. H. Freeman and Company. Gere, J. M., and H. C. Shaw, H. C. 1984. Terra Non Firma. New York, New York: W. H. Freeman and Company. Naiem, F., and J. C. Anderson. 2002. “Probabilistic Methods in Earthquake Engineering.” In Mechanics for a New Millenium, proceedings of the 20th International Congress of Theoretical and Applied Mechanics Chicago, Illinois, USA 27 August – 2 September 2000. Reiter, L. 1990. Earthquake Hazard Analysis. New York, New York: Columbia University Press. Seed H. B. and I. M. Idriss. 1971. “Simplified Procedure for Evaluating Soil Liquefaction Potential, J. Soil Mech. & Foundations Div., ASCE, 97(9), 1249-1273. FEMA 451B Topic 2 Notes Earthquake Mechanics 2 - 1 Earthquakes: Cause and Effect • Why earthquakes occur • How earthquakes are measured • Earthquake effects • Mitigation strategy • Earthquake time histories Instructional Material Complementing FEMA 451, Design Examples Earthquake Mechanics 2 - 2 This series of slides introduces the source and effect of ground motions. -
Overview and Recent Progress in Earthquake Prediction Research in Japan
Overview and Recent Progress in Earthquake Prediction Research in Japan Koshun YAMAOKA 山岡耕春 Graduate School of Environmental Studies Nagoya University 名古屋大学環境学研究科 地震火山・防災研究中心 contents Earthquake Prediction Research Systematization Historical overview of Japanese program Strategy in the new program of earthquake prediction research Noticeable results Published in May 2007 Systematization (1) Requirements in earthquake prediction WHEN (Time) WHERE (Place) HOW BIG (Magnitude) Earthquake prediction is to know these components with practical accuracy before an earthquake. Systematization(2) Classification of earthquake prediction in terms of time accuracy. Long-term prediction Statistical prediction using time history of earthquake occurrence. Mid-term prediction Computer simulation based on physical model using monitoring data. Short-term prediction Prediction using precursory phenomena of earthquakes. Present State of earthquake prediction (in Japan) Long-term Mid-term Short-term (tens to hundreds years) (years to months) (Days to hours) Almost established for Place inter-plate and active Same as left Same as left faults Almost established for Magnitude inter-plate and active Same as left Same as left faults Issued by the Under Under Time government development development National earthquake prediction program (Old program) 1965-1998 1. Establishment of nationwide observation network • Seismic observation network • Telemetry network • Deep borehole measurement in Tokyo metropolitan area • Strain observation network • Bury-in type volumetric strainmeters in Kanto-Tokai 2. Detection of precursors for long-term and short-term prediction of earthquakes • Seismic gap, for long-term precursor • Seismicity, crustal deformation etc… • Basic research Short-term precursors before 1978 Izu- Oshima Kinkai Earthquake. -One of the very few examples. From the Brochure of Earthquake prediction program (1991) New national program for earthquake prediction research 1. -
Assessment of Interplate and Intraplate Earthquakes
ASSESSMENT OF INTERPLATE AND INTRAPLATE EARTHQUAKES A Thesis by SRIGIRI SHANKAR BELLAM Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE August 2012 Major Subject: Construction Management Assessment of Interplate and Intraplate Earthquakes Copyright 2012 Srigiri Shankar Bellam ASSESSMENT OF INTERPLATE AND INTRAPLATE EARTHQUAKES A Thesis by SRIGIRI SHANKAR BELLAM Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Approved by: Chair of Committee, John M. Nichols Committee Members, Anne B. Nichols Douglas F. Wunneburger Leslie H. Feigenbaum Head of Department, Joseph P. Horlen August 2012 Major Subject: Construction Management iii ABSTRACT Assessment of Interplate and Intraplate Earthquakes. (August 2012) Srigiri Shankar Bellam, B. Tech, National Institute of Technology, India Chair of Advisory Committee: Dr. John M. Nichols The earth was shown in the last century to have a surface layer composed of large plates. Plate tectonics is the study of the movement and stresses in the individual plates that make up the complete surface of the world’s sphere. Two types of earthquakes are observed in the surface plates, interplate and intraplate earthquakes, which are classified, based on the location of the origin of an earthquake either between two plates or within the plate respectively. Limited work has been completed on the definition of the boundary region between the plates from which interplate earthquakes originate, other than the recent work on the Mid Atlantic Ridge, defined at two degrees and the subsequent work to look at the applicability of this degree based definition. -
2010 1. How Do Earthquakes Occur?
CE Earthquake Review- 2010 1. How do earthquakes occur? They occur by tectonic plates moving past each other. 2. What are the three different plate boundaries? Transform, convergent, divergent. 3. What are some effects of earthquakes? Mountains can be formed, volcanoes can be formed, and trenches can be formed. 4. What is a convergent plate boundary? When two plates collide. 5. What is a divergent plate boundary? When two plates separate. 6. What is a transform plate boundary? When two plates slide past each other. 7. How are mountains formed? It’s created by a convergent plate boundary. 8. What are the layers of the earth? Crust, mantle, outer core, and inner core. 9. How did the scientists know Pangaea existed? Fossils, rocks, climate, and the fit of the continents. 10. How do scientists know about the layers of the earth? Earthquakes waves travel to seismograph stations through the inner earth. 11. What causes convection currents? Uneven heating 12. What causes earthquakes? Convection currents in the earth’s mantle move tectonic plates and build up pressure that is suddenly released, causing earthquakes. 13. What is the difference between an S-wave and a P-wave? P-wave is faster (Push and Pull), S-wave is slower (Side to Side) 14. What causes a rift valley? A divergent plate boundary spreading apart and filling with magma. 15. What is a subduction zone? A convergent plate boundary where one plate is pushed under another. 16. What is the inner core made of and how do we know? Iron and nickel because the earth has a magnetic field.