scholarly journals The 1946 Unimak Tsunami Earthquake Area: revised tectonic structure in reprocessed seismic images and a suspect near field tsunami source

2014 ◽  
Author(s):  
John J. Miller ◽  
Roland E. von Huene ◽  
Holly F. Ryan
Keyword(s):  
Near Field ◽  
Tsunami Source ◽  
Tectonic Structure ◽  
Tsunami Earthquake ◽  
Seismic Images ◽  
Earthquake Area

OBSERVATION AND SIMULATION OF TSUNAMIS INDUCED BY THE 2003 TOKACHI-OKI EARTHQUAKE (M 8.0)

2015 ◽  
Vol 2 (3) ◽  
Author(s):  
Tatsuo Ohmachi ◽  
Shusaku Inoue ◽  
Tetsuji Imai
Keyword(s):  
Rayleigh Wave ◽  
Water Pressure ◽  
Near Field ◽  
Source Region ◽  
Tsunami Source ◽  
Band Pass Filter ◽  
Pass Filter ◽  
Tsunami Simulation ◽  
Sea Bed ◽  
Band Pass

The 2003 Tokachi-oki earthquake (MJ 8.0) occurred off the southeastern coast of Tokachi, Japan, and generated a large tsunami which arrived at Tokachi Harbor at 04:56 with a wave height of 4.3 m. Japan Marine Science and Technology Center (JAMSTEC) recovered records of water pressure and sea-bed acceleration at the bottom of the tsunami source region. These records are first introduced with some findings from Fourier analysis and band-pass filter analysis. Water pressure disturbance lasted for over 30 minutes and the duration was longer than those of accelerations. Predominant periods of the pressure looked like those excited by Rayleigh waves. Next, numerical simulation was conducted using the dynamic tsunami simulation technique able to represent generation and propagation of Rayleigh wave and tsunami, with a satisfactory result showing validity and usefulness of this technique. Keywords: Earthquake, Rayleigh wave, tsunami, near-field

Reexamination of Tsunami Source Models For the 20th Century Earthquakes Off Hokkaido and Tohoku Along the Eastern Margin of the Sea of Japan

2021 ◽  
Author(s):  
Satoko Murotani ◽  
Kenji Satake ◽  
Takeo Ishibe ◽  
Tomoya Harada
Keyword(s):  
20Th Century ◽  
Sea Of Japan ◽  
Near Field ◽  
Active Faults ◽  
Source Area ◽  
Tsunami Source ◽  
The Sea Of Japan ◽  
Scaling Relation ◽  
Multiple Faults ◽  
Tsunami Waveforms

Abstract Large earthquakes around Japan occur not only in the Pacific Ocean but also in the Sea of Japan, and cause both damage from the earthquake itself and from the ensuing tsunami to the coastal areas. Recently, offshore active fault surveys were conducted in the Sea of Japan by the Integrated Research Project on Seismic and Tsunami Hazards around the Sea of Japan (JSPJ), and their fault models (length, width, strike, dip, and slip angles) have been obtained. We examined the causative faults of M7 or larger earthquakes in the Sea of Japan during the 20th century using seismic and tsunami data. The 1940 off Shakotan Peninsula earthquake (MJMA 7.5) appears to have been caused by the offshore active faults MS01, MS02, ST01, and ST02 as modelled by the JSPJ. The 1993 off the southwest coast of Hokkaido earthquake (MJMA 7.8) likely occurred on the offshore active faults OK03a, OK03b, and OK05, while the 1983 Central Sea of Japan earthquake (MJMA 7.7) probably related to MMS01, MMS04, and MGM01. For these earthquakes, the observed tsunami waveforms were basically reproduced by tsunami numerical simulation from the offshore active faults with the slip amounts obtained by the scaling relation with three stages between seismic moment and source area for inland earthquakes. However, the observed tsunami runup heights along the coast were not reproduced at certain locations, possibly because of the coarse bathymetry data used for the simulation. The 1983 west off Aomori (MJMA 7.1) and the 1964 off Oga Peninsula (MJMA 6.9) earthquakes showed multiple faults near the source area that could be used to reproduce the observed tsunami waveforms; therefore, we could not identify the causative faults. Further analysis using near-field seismic waveforms is required for their identification of their causative faults and their parameters. The scaling relation for inland earthquakes can be used to obtain the slip amounts for offshore active faults in the Sea of Japan and to estimate the coastal tsunami heights and inundation area which can be useful for disaster prevention and mitigation of future earthquakes and tsunamis in the Sea of Japan.

Testing Slip Models for Tsunami Generation

2021 ◽  
Author(s):  
Hafize Başak Bayraktar ◽  
Antonio Scala ◽  
Stefano Lorito ◽  
Manuela Volpe ◽  
Carlos Sánchez Linares ◽  
...  
Keyword(s):  
Subduction Zones ◽  
Near Field ◽  
Ocean Model ◽  
Tsunami Hazard ◽  
Slip Distribution ◽  
Tsunami Source ◽  
Tsunami Observations ◽  
The Pacific ◽  
Tsunami Waveforms ◽  
The Pacific Ocean

<p>Tsunami hazard depends strongly on the slip distribution of a causative earthquake. Simplified uniform slip models lead to underestimating the tsunami wave height which would be generated by a more realistic heterogeneous slip distribution, both in the near-field and in the far-field of the tsunami source. Several approaches have been proposed to generate stochastic slip distributions for tsunami hazard calculations, including in some cases shallow slip amplification (Le Veque et al., 2016; Sepulveda et al., 2017; Davies 2019; Scala et al., 2020). However, due to the relative scarcity of tsunami data, the inter-comparison of these models and the calibration of their parameters against observations is a challenging yet very much needed task, also in view of their use for tsunami hazard assessment.</p><p>Davies (2019) compared a variety of approaches, which consider both depth-dependent and depth-independent slip models in subduction zones by comparing the simulated tsunami waveforms with DART records of 18 tsunami events in the Pacific Ocean. Model calibration was also proposed by Davies and Griffin (2020).</p><p>Here, to further progress along similar lines, we compare synthetic tsunamis produced by kinematic slip models obtained with teleseismic inversions from Ye et al. (2016) and by recent stochastic slip generation techniques (Scala et al., 2020) against tsunami observations at open ocean DART buoys, for the same 18 earthquakes and ensuing tsunamis analyzed by Davies (2019). Given the magnitude and location of the real earthquakes, we consider ensembles of consistent slipping areas and slip distributions, accounting for both constant and depth-dependent rigidity models. Tsunami simulations are performed for about 68.000 scenarios in total, using the Tsunami-HySEA code (Macías et al., 2016). The simulated results are validated and compared to the DART observations in the same framework considered by Davies (2019).</p>

scholarly journals Source modeling and spectral analysis of the Crete tsunami of 2nd May 2020 along the Hellenic Subduction Zone, offshore Greece

2021 ◽  
Vol 73 (1) ◽  
Author(s):  
Mohammad Heidarzadeh ◽  
Aditya Riadi Gusman
Keyword(s):  
Spectral Analysis ◽  
Tide Gauge ◽  
Eastern Mediterranean ◽  
Near Field ◽  
Tsunami Source ◽  
Source Inversion ◽  
Source Modeling ◽  
Crete Island ◽  
Tsunami Source Inversion ◽  
Wave Trains

AbstractTsunami hazard in the Eastern Mediterranean Basin (EMB) has attracted attention following three tsunamis in this basin since 2017 namely the July 2017 and October 2020 Turkey/Greece and the May 2020 offshore Crete Island (Greece) tsunamis. Unique behavior is seen from tsunamis in the EMB due to its comparatively small size and confined nature which causes several wave reflections and oscillations. Here, we studied the May 2020 event using sea level data and by applying spectral analysis, tsunami source inversion, and numerical modeling. The maximum tsunami zero-to-crest amplitudes were measured 15.2 cm and 6.5 cm at two near-field tide gauge stations installed in Ierapetra and Kasos ports (Greece), respectively. The dominant tsunami period band was 3.8–4.7 min. We developed a heterogeneous fault model having a maximum slip of 0.64 m and an average slip of 0.28 m. This model gives a seismic moment of 1.13 × 1019 Nm; equivalent to Mw 6.67. We observed three distinct wave trains on the wave record of the Ierapetra tide gauge: the first and the second wave trains carry waves with periods close to the source period of the tsunami, while the third train is made of a significantly-different period of 5–10 min.

Seismic Images of Modern Convergent Margin Tectonic Structure

1986 ◽  
Author(s):  
Roland von Huene ◽  
Susan Vath ◽  
Christine Sperber ◽  
Bridgett Fulop ◽  
Lee Bailey ◽  
...  
Keyword(s):  
Convergent Margin ◽  
Tectonic Structure ◽  
Seismic Images

scholarly journals Probabilistic near-field tsunami source and tsunami run-up distribution inferred from tsunami run-up records in northern Chile

2021 ◽  
Author(s):  
Jun-Whan Lee ◽  
Jennifer Irish ◽  
Robert Weiss
Keyword(s):  
Moment Tensor ◽  
Near Field ◽  
The United States ◽  
Tsunami Source ◽  
United States Geological Survey ◽  
Northern Chile ◽  
Study Results ◽  
Run Up ◽  
Tsunami Run Up

Understanding a tsunami source and its impact is vital to assess a tsunami hazard. Thanks to the efforts of the tsunami survey teams, high-quality tsunami run-up data exists for contemporary events. Still, it has not been widely used to infer a tsunami source and its impact mainly due to the computational burden of the tsunami forward model. In this study, we propose a TRRF-INV (Tsunami Run-up Response Function-based INVersion) model that can provide probabilistic estimates of a near-field tsunami source and tsunami run-up distribution from a small number of run-up records. We tested the TRRF-INV model with synthetic tsunami scenarios in northern Chile and applied it to the 2014 Iquique, Chile, tsunami event as a case study. The results demonstrated that the TRRF-INV model can provide a reasonable tsunami source estimate to first order and estimate tsunami run-up distribution well. Moreover, the case study results agree well with the United States Geological Survey report and the global Centroid Moment Tensor solution. We also analyzed the performance of the TRRF-INV model depending on the number and the uncertainty of run-up records. We believe that the TRRF-INV model has the potential for supporting accurate hazard assessment by (1) providing new insights from tsunami run-up records into the tsunami source and its impact, (2) using the TRRF-INV model as a tool to support existing tsunami inversion models, and (3) estimating a tsunami source and its impact for ancient events where no data other than estimated run-up from sediment deposit data exists.

Sign in / Sign up

Export Citation Format

Share Document