Study on the 1906 Colombia‐Ecuador megathrust earthquake based on tsunami waveforms observed at tide gauges: release variation of accumulated slip‐deficits in the source area

2021 ◽  
Author(s):  
Yusuke Yamanaka ◽  
Yuichiro Tanioka
Keyword(s):  
Source Area ◽  
Tide Gauges ◽  
Megathrust Earthquake ◽  
Tsunami Waveforms

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.

 The source characteristics and tsunami resonance effect of the 2020 Samos earthquake in Eastern Aegean

2021 ◽  
Author(s):  
Gui Hu ◽  
Wanpeng Feng ◽  
Yuchen Wang ◽  
Linlin Li ◽  
Xiaohui He ◽  
...  
Keyword(s):  
Normal Fault ◽  
Coastal Areas ◽  
Wave Period ◽  
Tsunami Source ◽  
Tide Gauges ◽  
Tsunami Waves ◽  
Source Characteristics ◽  
The North ◽  
Eastern Aegean ◽  
Tsunami Waveforms

<p>On October 30 2020 11:51 UTC, a Mw 6.9 normal fault earthquake occurred off the northern coasts of Samos Island, Eastern Aegean, Greece. Over a 120 people were killed and more than 1000 people were injured during the seismic sequence. The quake produced a moderate tsunami that swapped the coastal areas of Izmir (Turkey) and Samos (Greece) with inundation heights up to ~3 m. Finding the source of such a tsunami has been puzzling as a normal fault earthquake with Mw 6.9 would not be considered significant enough to generate metric-scale waves. Furthermore, the lack of near-field observations has made the identification of the seismogenic fault responsible for the mainshock difficult. In this study, we infer the source characteristics from multiple observation data, including InSAR, GPS, teleseismic waves and tsunami waves. We first  generate two Sentinel-1 co-seismic interferograms with a maximum Line of Sight (LOS) change of 8 cm on the coastal areas at the Samos island. We obtain a north-dipping fault model, which can slightly better explain the geodetic observations and teleseismic P waves. To understand the potential tsunami source, we use several earthquake slip models collected from different research groups to conduct tsunami simulations.  Comparing simulated tsunami waveforms with those measured at 6 local tide gauges, we show that the north-dipping fault can fit tsunami records better than the south-dipping fault. The north-dipping fault hypothesis is also further supported by the spatial distributions of the aftershocks. The spectral analysis of tsunami waveforms at selected tide gauges suggests that the tsunami period band is within 4.6 ~ 21.3 min and the primary wave period is ~14.2 min. Using this wave period as an indirect constraint, we show that the source dimension of our slip model can produce tsunami waveforms with similar wave period. We also find high-energy wave of the Samos earthquake that lasted 20 h, and fundamental oscillation periods of Sığacık Bay are remarkably close to some dominating tsunami periods. We infer the coseismic seafloor displacement alone is not enough to create disastrous effects on coastal cities; therefore we suggest that the tsunami waves may have been amplified by local coastline and tsunami resonance with local bay, or another source, e.g. triggered landslides.</p>

scholarly journals Benchmarking the Optimal Time Alignment of Tsunami Waveforms in Nonlinear Joint Inversions for the Mw 8.8 2010 Maule (Chile) Earthquake

2020 ◽  
Vol 8 ◽  
Author(s):  
F. Romano ◽  
S. Lorito ◽  
T. Lay ◽  
A. Piatanesi ◽  
M. Volpe ◽  
...  
Keyword(s):  
Coseismic Deformation ◽  
Optimal Time ◽  
Tide Gauges ◽  
First Order ◽  
Time Alignment ◽  
Finite Fault ◽  
Chile Earthquake ◽  
Tsunami Waveforms ◽  
Maule Earthquake ◽  
Seafloor Deformation

Finite-fault models for the 2010 Mw 8.8 Maule, Chile earthquake indicate bilateral rupture with large-slip patches located north and south of the epicenter. Previous studies also show that this event features significant slip in the shallow part of the megathrust, which is revealed through correction of the forward tsunami modeling scheme used in tsunami inversions. The presence of shallow slip is consistent with the coseismic seafloor deformation measured off the Maule region adjacent to the trench and confirms that tsunami observations are particularly important for constraining far-offshore slip. Here, we benchmark the method of Optimal Time Alignment (OTA) of the tsunami waveforms in the joint inversion of tsunami (DART and tide-gauges) and geodetic (GPS, InSAR, land-leveling) observations for this event. We test the application of OTA to the tsunami Green’s functions used in a previous inversion. Through a suite of synthetic tests we show that if the bias in the forward model is comprised only of delays in the tsunami signals, the OTA can correct them precisely, independently of the sensors (DART or coastal tide-gauges) and, to the first-order, of the bathymetric model used. The same suite of experiments is repeated for the real case of the 2010 Maule earthquake where, despite the results of the synthetic tests, DARTs are shown to outperform tide-gauges. This gives an indication of the relative weights to be assigned when jointly inverting the two types of data. Moreover, we show that using OTA is preferable to subjectively correcting possible time mismatch of the tsunami waveforms. The results for the source model of the Maule earthquake show that using just the first-order modeling correction introduced by OTA confirms the bilateral rupture pattern around the epicenter, and, most importantly, shifts the inferred northern patch of slip to a shallower position consistent with the slip models obtained by applying more complex physics-based corrections to the tsunami waveforms. This is confirmed by a slip model refined by inverting geodetic and tsunami data complemented with a denser distribution of GPS data nearby the source area. The models obtained with the OTA method are finally benchmarked against the observed seafloor deformation off the Maule region. We find that all of the models using the OTA well predict this offshore coseismic deformation, thus overall, this benchmarking of the OTA method can be considered successful.

scholarly journals Detailed analysis of tsunami waveforms generated by the 1946 Aleutian tsunami earthquake

2001 ◽  
Vol 1 (4) ◽  
pp. 171-175 ◽  
Author(s):  
Y. Tanioka ◽  
T. Seno
Keyword(s):  
Seismic Moment ◽  
Seismic Waves ◽  
Boussinesq Equation ◽  
Fault Model ◽  
Japan Trench ◽  
Tsunami Generation ◽  
Tide Gauges ◽  
Tsunami Waveforms ◽  
Tsunami Earthquake ◽  
20 Nm

Abstract. The 1946 Aleutian earthquake was a typical tsunami earthquake which generated abnormally larger tsunami than expected from its seismic waves. Previously, Johnson and Satake (1997) estimated the fault model of this earthquake using the tsunami waveforms observed at tide gauges. However, they did not model the second pulse of the tsunami at Honolulu although that was much larger than the first pulse. In this paper, we numerically computed the tsunami waveforms using the linear Boussinesq equation to determine the fault model which explains the observed tsunami waveforms including the large second pulse observed at Honolulu. The estimated fault width is 40–60 km which is much narrower than the fault widths of the typical great underthrust earthquakes, the 1957 Aleutian and the 1964 Alasuka earthquakes. A previous study of the 1896 Sanriku earthquake, another typical tsunami earthquake, suggested that the additional uplift of the sediments near the Japan Trench had a large effect on the tsunami generation. In this study, we also show that the additional uplift of the sediments near the trench, due to a large coseismic horizon-tal movement of the backstop, had a significant effect on the tsunami generation of the 1946 Aleutian earthquake. The estimated seismic moment of the 1946 Aleutian earthquake is 17–19 × 1020 20 Nm (Mw 8.1).

scholarly journals TSUNAMI RESONANCE IN THE PALMA DE MAJORCA BAY AND HARBOUR INDUCED BY THE 2003 BOUMERDES-ZEMMOURI ALGERIAN EARTHQUAKE (WESTERN MEDITERRANEAN)

2011 ◽  
Vol 1 (32) ◽  
pp. 7 ◽  
Author(s):  
Jordi Vela ◽  
Begoña Pérez ◽  
Mauricio González ◽  
Luis Otero ◽  
Maitane Olabarrieta ◽  
...  
Keyword(s):  
High Frequency ◽  
Source Area ◽  
Western Mediterranean ◽  
Interesting Case ◽  
Resonance Phenomenon ◽  
Economic Losses ◽  
Tide Gauges ◽  
Resonance Effects ◽  
High Frequency Oscillations ◽  
Palma De Mallorca

During the tsunami of May 2003 in the Balearic Islands, generated by the Algerian earthquake, most of the damage and economic losses occurred inside the harbours, due to high frequency oscillations of relatively large amplitude, combined effect of the tsunami and local resonances. It can be said in fact that this was the more important effect at the islands, where no important inundations is known to have occurred outside the harbours, showing up that even tsunamis with low amplitudes can cause serious damages due to resonance effects. Several tide gauges recorded the seismic-generated tsunami, so comparison of simulations and observations became possible, and made this event a very interesting case for modeling experiments. The main objectives of this work is to understand how was the energy transformation of the tsunami from the source area to the Palma de Mallorca bay and harbour, and to verify if a resonance phenomenon was induced in the harbour.

Permo-Carboniferous sediments at Kraskov (borehole KS-1) and their source area

2015 ◽  
Author(s):  
Marcela Stárková ◽  
Štěpánka Mrázová ◽  
Tamara Sidorinová
Keyword(s):  
Source Area

Analysis and prediction of storm water levels in Delaware inland bays

Shore & Beach ◽  
2019 ◽  
pp. 29-35
Author(s):  
Michele Strazzella ◽  
Nobuhisa Kobayashu ◽  
Tingting Zhu
Keyword(s):  
Analytical Model ◽  
Tide Gauge ◽  
Hurricane Sandy ◽  
Water Levels ◽  
Tide Gauges ◽  
Storm Tide ◽  
Barrier Beach ◽  
Wave Overtopping ◽  
Inland Bays ◽  
Damping Parameter

A simple approach based on an analytical model and available tide gauge data is proposed for the analysis of storm tide damping inside inland bays with complex bathymetry and for the prediction of peak water levels at gauge locations during storms. The approach was applied to eight tide gauges in the vicinity of inland bays in Delaware. Peak water levels at the gauge locations were analyzed for 34 storms during 2005-2017. A damping parameter in the analytical model was calibrated for each bay gauge. The calibrated model predicted the peak water levels within errors of about 0.2 m except for Hurricane Sandy in 2012. The analytical model including wave overtopping was used to estimate the peak wave overtopping rate over the barrier beach from the measured peak water level in the adjacent bay.

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