Detailed Analysis of Tsunami Waveforms Generated by the 1946 Aleutian Tsunami Earthquake
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Tracking Past Earthquakes in the Sediment Record Testing and Developing Submarine Paleoseismology in the Deep Sea (JTRACK‐Paleoseismology)
IODP Expedition 386: Japan Trench Paleoseismology TRACKing past earthquakes in the sediment record Testing and developing submarine Paleoseismology in the deep sea (JTRACK‐Paleoseismology) IODP Expedition 386: Japan Trench Paleoseismology Co‐Chief Scientists: Michael Strasser (University of Innsbruck, Austria) Ken Ikehara (Geological Survey of Japan, AIST) Expedition Project Manager: Jez Everest, British Geological Survey Lena Maeda, JAMSTEC (MarE3 Liasion) JpGU 2020 2020-07-12 Michi Strasser IODP Expedition 386: Japan Trench Paleoseismology Short historical and even shorter instrumental records limit our perspective of earthquake maximum magnitude and recurrence Examining prehistoric events preserved in the geological record is essential to understand long‐term history of giant earthquakes JpGU 2020 2020-07-12 Michi Strasser IODP Expedition 386: Japan Trench Paleoseismology “Submarine paleoseismology” is a promising approach to investigate deposits from the deep sea, where earthquakes leave traces preserved in stratigraphic succession. Submarine paleoseismology study sites (numbers) compiled during Magellan Plus Workshop in Zürich 2015 (McHugh et al., 2016; Strasser et al., 2016) JpGU 2020 2020-07-12 Michi Strasser IODP Expedition 386: Japan Trench Paleoseismology Challenges in Submarine Paleoseismology Can we distinguish different earthquake events and types from the sedimentary records? Is there an earthquake magnitude threshold for a given signal/pattern in the geological record? Does record sensitivity change by margin segmentation, sedimentation and/or through time? Can we link the sedimentary signal to the earthquake rupture characteristics? McHugh et al., 2016; Strasser et al., 2016) JpGU 2020 2020-07-12 Michi Strasser IODP Expedition 386: Japan Trench Paleoseismology IODP is uniquely positioned to provide data by coring sequences comprising continuous depositional conditions and records of earthquakes occurrence over longer time periods. -
The Moment Magnitude and the Energy Magnitude: Common Roots
The moment magnitude and the energy magnitude : common roots and differences Peter Bormann, Domenico Giacomo To cite this version: Peter Bormann, Domenico Giacomo. The moment magnitude and the energy magnitude : com- mon roots and differences. Journal of Seismology, Springer Verlag, 2010, 15 (2), pp.411-427. 10.1007/s10950-010-9219-2. hal-00646919 HAL Id: hal-00646919 https://hal.archives-ouvertes.fr/hal-00646919 Submitted on 1 Dec 2011 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Click here to download Manuscript: JOSE_MS_Mw-Me_final_Nov2010.doc Click here to view linked References The moment magnitude Mw and the energy magnitude Me: common roots 1 and differences 2 3 by 4 Peter Bormann and Domenico Di Giacomo* 5 GFZ German Research Centre for Geosciences, Telegrafenberg, 14473 Potsdam, Germany 6 *Now at the International Seismological Centre, Pipers Lane, RG19 4NS Thatcham, UK 7 8 9 Abstract 10 11 Starting from the classical empirical magnitude-energy relationships, in this article the 12 derivation of the modern scales for moment magnitude M and energy magnitude M is 13 w e 14 outlined and critically discussed. The formulas for Mw and Me calculation are presented in a 15 way that reveals, besides the contributions of the physically defined measurement parameters 16 seismic moment M0 and radiated seismic energy ES, the role of the constants in the classical 17 Gutenberg-Richter magnitude-energy relationship. -
Large and Repeating Slow Slip Events in the Izu-Bonin Arc from Space
LARGE AND REPEATING SLOW SLIP EVENTS IN THE IZU-BONIN ARC FROM SPACE GEODETIC DATA (伊豆小笠原弧における巨大スロー地震および繰り返し スロー地震の宇宙測地学的研究) by Deasy Arisa Department of Natural History Sciences Graduate School of Science, Hokkaido University September, 2016 Abstract The Izu-Bonin arc lies along the convergent boundary where the Pacific Plate subducts beneath the Philippine Sea Plate. In the first half of my three-year doctoral course, I focused on the slow deformation on the Izu Islands, and later in the second half, I focused on the slow deformation on the Bonin Islands. The first half of the study, described in Chapter V, is published as a paper, "Transient crustal movement in the northern Izu–Bonin arc starting in 2004: A large slow slip event or a slow back-arc rifting event?". Horizontal velocities of continuous Global Navigation Satellite System (GNSS) stations on the Izu Islands move eastward by up to ~1 cm/year relative to the stable part of the Philippine Sea Plate suggesting active back-arc rifting behind the northern part of the arc. We confirmed the eastward movement of the Izu Islands explained by Nishimura (2011), and later discussed the sudden accelerated movement in the Izu Islands detected to have occurred in the middle of 2004. I mainly discussed this acceleration and make further analysis to find out the possible cause of this acceleration. Here I report that such transient eastward acceleration, starting in the middle of 2004, resulted in ~3 cm extra movements in three years. I compare three different mechanisms possibly responsible for this transient movement, i.e. (1) postseismic movement of the 2004 September earthquake sequence off the Kii Peninsula far to the west, (2) a temporary activation of the back-arc rifting to the west dynamically triggered by seismic waves from a nearby earthquake, and (3) a large slow slip event in the Izu-Bonin Trench to the east. -
Relation of Slow Slip Events to Subsequent Earthquake Rupture
Earthquake and tsunami forecasts: Relation of slow slip events to subsequent earthquake rupture Timothy H. Dixona,1, Yan Jiangb, Rocco Malservisia, Robert McCaffreyc, Nicholas Vossa, Marino Prottid, and Victor Gonzalezd aSchool of Geosciences, University of South Florida, Tampa, FL 33620; bPacific Geoscience Centre, Geological Survey of Canada, BC, Canada V8L 4B2; cDepartment of Geology, Portland State University, Portland, OR 97201; and dObservatorio Vulcanológico y Sismológico de Costa Rica, Universidad Nacional, Heredia 3000, Costa Rica Edited* by David T. Sandwell, Scripps Institution of Oceanography, La Jolla, CA, and approved October 24, 2014 (received for review June 30, 2014) The 5 September 2012 Mw 7.6 earthquake on the Costa Rica sub- Geologic and Seismic Background duction plate boundary followed a 62-y interseismic period. High- The Nicoya Peninsula forms the western edge of the Caribbean precision GPS recorded numerous slow slip events (SSEs) in the plate, where the Cocos plate subducts beneath the Caribbean decade leading up to the earthquake, both up-dip and down-dip plate along the Middle American Trench at about 8 cm/y (3). The of seismic rupture. Deeper SSEs were larger than shallower ones region has a well-defined earthquake cycle, with large (M > 7) and, if characteristic of the interseismic period, release most lock- earthquakes in 1853, 1900, 1950 (M 7.7), and most recently 5 ing down-dip of the earthquake, limiting down-dip rupture and September 2012 (Mw 7.6). Smaller (M ∼ 7) events in 1978 and earthquake magnitude. Shallower SSEs were smaller, accounting 1990 have also occurred nearby (4). Large tsunamis have not for some but not all interseismic locking. -
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. -
Rapid Identification of Tsunamigenic Earthquakes Using GNSS
www.nature.com/scientificreports OPEN Rapid identifcation of tsunamigenic earthquakes using GNSS ionospheric sounding Fabio Manta1,2,4*, Giovanni Occhipinti 3,4, Lujia Feng 1 & Emma M. Hill 1,2 The largest tsunamis are generated by seafoor uplift resulting from rupture of ofshore subduction- zone megathrusts. The rupture of the shallowest part of a megathrust often produces unexpected outsize tsunami relative to their seismic magnitude. These are so called ‘tsunami earthquakes’, which are difcult to identify rapidly using the current tsunami warning systems, even though, they produce some of the deadliest tsunami. We here introduce a new method to evaluate the tsunami risk by measuring ionospheric total electron content (TEC). We examine two Mw 7.8 earthquakes (one is a tsunami earthquake and the other is not) generated in 2010 by the Sunda megathrust, ofshore Sumatra, to demonstrate for the frst time that observations of ionospheric sounding from Global Navigation Satellite System (GNSS) can be used to evaluate the tsunamigenic potential of earthquakes as early as 8 min after the mainshock. ‘Tsunami earthquakes’, as originally defned by Kanamori 1, are events generating tsunami with larger amplitude than expected from their seismic magnitude. Most tsunami earthquakes are generated by high levels of slip on the shallow megathrust, which results in large seafoor uplifs and hence very dangerous tsunami. Te shallow location of the slip—close to the subduction trench—means that the ruptures generating tsunami earthquakes are at signifcant distance from land-based monitoring networks, limiting our ability to quickly and accurately assess their magnitude and source parameters. Conventional approaches using various seismological methods2–4 or rapid inversion of GNSS (Global Navigation Satellite System) estimates of ground motion5 regularly encounter difculties in accurately estimating the uplif of the seafoor and consequently fail in predicting the tsunamigenic nature of tsunami earthquakes. -
Mw9- Class Earthquakes Versus Smaller Earthquakes and Other Driving Mechanisms
Expedition Co-chief Scientists Prof. Michael Strasser Michael Strasser is a professor in sedimentary geology at the University of Innsbruck in Austria. His research focuses on the quantitative characterization of dynamic sedimentary and tectonic processes and related geohazards, as unraveled from the event-stratigraphic record of lakes and ocean margins. “Michi” has participated in 5 ocean drilling expeditions to subduction zones (including Nankai Trough Seismogenic Zone The Japan Trench Experiment Expedition 338 as Co-chief) and has received the 2017 AGU/JpGU Asahiko Taira International Scientific Ocean Paleoseismology Drilling Research Prize for his outstanding contributions 6 3 to the investigation of submarine mass movements using Deposit (x 10 m ) multidisciplinary approaches through scientific ocean drilling. Expedition His work on submarine paleoseismology has focused on the Japan Trench since the 2011 Tohoku-oki earthquake, Volume 70 after which he lead two research cruises to characterize the offshore impact of the earthquake on the hadal sedimentary environment. Dr. Ken Ikehara Error Ken Ikehara is a prime senior researcher in the Research Institute of Geology 60 and Geoinformation, Geological Survey of Japan, AIST. His research focuses Mid-value on sedimentology and marine geology of active margins, with special interests in sedimentary processes, formation and preservation of event deposits, Quaternary paleoceanography and Asian monsoon fluctuation. His work on submarine 50 paleoseismology has concentrated not only on the Japan Trench but also on the Nankai Trough, Ryukyu Trench and northern Japan Sea. Ken attended more than 80 survey cruises, mainly around the Japanese islands, including US Sumatra-Andaman Trench, German-Japan Japan Trench, 2000 French Antarctic Ocean cruises, and the IODP Exp 346 Asian monsoon. -
Outer-Rise Normal Fault Development and Influence On
Boston et al. Earth, Planets and Space 2014, 66:135 http://www.earth-planets-space.com/content/66/1/135 FULL PAPER Open Access Outer-rise normal fault development and influence on near-trench décollement propagation along the Japan Trench, off Tohoku Brian Boston1*, Gregory F Moore1, Yasuyuki Nakamura2 and Shuichi Kodaira2 Abstract Multichannel seismic reflection lines image the subducting Pacific Plate to approximately 75 km seaward of the Japan Trench and document the incoming plate sediment, faults, and deformation front near the 2011 Tohoku earthquake epicenter. Sediment thickness of the incoming plate varies from <50 to >600 m with evidence of slumping near normal faults. We find recent sediment deposits in normal fault footwalls and topographic lows. We studied the development of two different classes of normal faults: faults that offset the igneous basement and faults restricted to the sediment section. Faults that cut the basement seaward of the Japan Trench also offset the seafloor and are therefore able to be well characterized from multiple bathymetric surveys. Images of 199 basement-cutting faults reveal an average throw of approximately 120 m and average fault spacing of approximately 2 km. Faults within the sediment column are poorly documented and exhibit offsets of approximately 20 m, with densely spaced populations near the trench axis. Regional seismic lines show lateral variations in location of the Japan Trench deformation front throughout the region, documenting the incoming plate’s influence on the deformation front’s location. Where horst blocks are carried into the trench, seaward propagation of the deformation front is diminished compared to areas where a graben has entered the trench. -
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. -
10. Crustal Structure of the Japan Trench
10. CRUSTAL STRUCTURE OF THE JAPAN TRENCH: THE EFFECT OF SUBDUCTION OF OCEAN CRUST Sandanori Murauchi, Department of Earth Sciences, Chiba University, Chiba, Japan and William J. Ludwig, Lamont-Doherty Geological Observatory of Columbia University, Palisades, New York ABSTRACT Evaluation and synthesis of seismic-refraction measurements made in the Japan trench in the light of the results of deep-sea drill- ing from Glomar Challenger Legs 56 and 57 result in a schematic sec- tion of the crustal structure. The Pacific Ocean crustal plate under- thrusts the leading edge of the continental block of Northeast Japan at a low angle and follows at depth the upper seismic belt of the Wadati-Benioff zone. Overthrust continental crust extends to within 30 km of the trench axis; thenceforward the lower inner trench slope is formed by a thick, wedge-shaped body of low-velocity sediments. The volume of these sediments is too small to represent all the sedi- ments scraped off the Pacific plate and transported from land. This indicates that substantial amounts of sediment are carried down along slip planes between the continental block and the descending plate. Dewatering of the sediments lubricates the slip planes. The slip planes migrate upward into the overlying continental edge, causing removal of material from its base. This tectonic erosion causes sub- sidence and landward retreat of the continental edge. INTRODUCTION between 39 and 40° N. Lines of multichannel seismic- reflection measurements were made by JAPEX to select In terms of plate tectonics, the convergence of two the prime drill sites (see foldouts, back cover, this crustal plates may result in underthrusting (subduction) volume, Part 1; Nasu et al., 1979). -
A Test for the Mediterranean Tsunami Warning System Mohammad Heidarzadeh1* , Ocal Necmioglu2 , Takeo Ishibe3 and Ahmet C
Heidarzadeh et al. Geosci. Lett. (2017) 4:31 https://doi.org/10.1186/s40562-017-0097-0 RESEARCH LETTER Open Access Bodrum–Kos (Turkey–Greece) Mw 6.6 earthquake and tsunami of 20 July 2017: a test for the Mediterranean tsunami warning system Mohammad Heidarzadeh1* , Ocal Necmioglu2 , Takeo Ishibe3 and Ahmet C. Yalciner4 Abstract Various Tsunami Service Providers (TSPs) within the Mediterranean Basin supply tsunami warnings including CAT-INGV (Italy), KOERI-RETMC (Turkey), and NOA/HL-NTWC (Greece). The 20 July 2017 Bodrum–Kos (Turkey–Greece) earth- quake (Mw 6.6) and tsunami provided an opportunity to assess the response from these TSPs. Although the Bodrum– Kos tsunami was moderate (e.g., runup of 1.9 m) with little damage to properties, it was the frst noticeable tsunami in the Mediterranean Basin since the 21 May 2003 western Mediterranean tsunami. Tsunami waveform analysis revealed that the trough-to-crest height was 34.1 cm at the near-feld tide gauge station of Bodrum (Turkey). Tsunami period band was 2–30 min with peak periods at 7–13 min. We proposed a source fault model for this tsunami with the length and width of 25 and 15 km and uniform slip of 0.4 m. Tsunami simulations using both nodal planes produced almost same results in terms of agreement between tsunami observations and simulations. Diferent TSPs provided tsunami warnings at 10 min (CAT-INGV), 19 min (KOERI-RETMC), and 18 min (NOA/HL-NTWC) after the earthquake origin time. Apart from CAT-INGV, whose initial Mw estimation difered 0.2 units with respect to the fnal value, the response from the other two TSPs came relatively late compared to the desired warning time of ~ 10 min, given the difculties for timely and accurate calculation of earthquake magnitude and tsunami impact assessment. -
Supercycle in Great Earthquake Recurrence Along the Japan Trench Over the Last 4000 Years Kazuko Usami1,5* , Ken Ikehara1, Toshiya Kanamatsu2 and Cecilia M
Usami et al. Geosci. Lett. (2018) 5:11 https://doi.org/10.1186/s40562-018-0110-2 RESEARCH LETTER Open Access Supercycle in great earthquake recurrence along the Japan Trench over the last 4000 years Kazuko Usami1,5* , Ken Ikehara1, Toshiya Kanamatsu2 and Cecilia M. McHugh3,4 Abstract On the landward slope of the Japan Trench, the mid-slope terrace (MST) is located at a depth of 4000–6000 m. Two piston cores from the MST were analyzed to assess the applicability of the MST for turbidite paleoseismology and to fnd out reliable recurrence record of the great earthquakes along the Japan Trench. The cores have preserved records of ~ 12 seismo-turbidites (event deposits) during the last 4000 years. In the upper parts of the two cores, only the following earthquakes (magnitude M ~ 8 and larger) were clearly recorded: the 2011 Tohoku, the 1896 Sanriku, the 1454 Kyotoku, and the 869 Jogan earthquake. In the lower part of the cores, turbidites were deposited alternately in the northern and southern sites during the periods between concurrent depositional events occurring at intervals of 500–900 years. Considering the characteristics of the coring sites for their sensitivity to earthquake shaking, the con- current depositional events likely correspond to a supercycle that follows giant (M ~ 9) earthquakes along the Japan Trench. Preliminary estimations of peak ground acceleration for the historical earthquakes recorded as the turbidites imply that each rupture length of the 1454 and 869 earthquakes was over 200 km. The earthquakes related to the supercycle have occurred over at least the last 4000 years, and the cycle seems to have become slightly shorter in recent years.