scholarly journals Three‐Dimensional Seismic Attenuation Structure of Central Japan and Deep Sources of Arc Magmatism

2019 ◽  
Vol 46 (23) ◽  
pp. 13746-13755 ◽  
Author(s):  
Hirokazu Kashiwagi ◽  
Junichi Nakajima
Keyword(s):  
Three Dimensional ◽  
Seismic Attenuation ◽  
Arc Magmatism ◽  
Central Japan ◽  
Attenuation Structure ◽  
Deep Sources

scholarly journals Three-dimensional Attenuation Structure beneath the Tokai Region, Central Japan Derived Using Local Earthquake Spectra

2012 ◽  
Vol 65 (2) ◽  
pp. 175-187 ◽  
Author(s):  
Hiroyuki TAKAOKA ◽  
Noriko TSUMURA ◽  
Fukusuke TAKAHASHI ◽  
Kenji NOZAKI ◽  
Aitaro KATO ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Central Japan ◽  
Local Earthquake ◽  
Attenuation Structure ◽  
Tokai Region

scholarly journals Detailed seismic attenuation structure beneath Hokkaido, northeastern Japan: Arc‐arc collision process, arc magmatism, and seismotectonics

2014 ◽  
Vol 119 (8) ◽  
pp. 6486-6511 ◽  
Author(s):  
Saeko Kita ◽  
Junichi Nakajima ◽  
Akira Hasegawa ◽  
Tomomi Okada ◽  
Kei Katsumata ◽  
...  
Keyword(s):  
Seismic Attenuation ◽  
Arc Magmatism ◽  
Collision Process ◽  
Northeastern Japan ◽  
Attenuation Structure

scholarly journals A tomography image of the Aegean region (Greece) derived from inversion of macroseismic intensity data

1997 ◽  
Vol 40 (1) ◽  
Author(s):  
G. N. Stavrakakis ◽  
G. Drakatos ◽  
G. Karantonis ◽  
D. Papanastassiou
Keyword(s):  
Lower Layer ◽  
Three Dimensional ◽  
Aegean Sea ◽  
Seismic Intensity ◽  
Seismic Attenuation ◽  
Intensity Data ◽  
Southeastern Part ◽  
Aegean Region ◽  
Mediterranean Regions ◽  
Attenuation Structure

The three-dimensional attenuation structure beneath the Aegean sea and the surrounding regions was determined by inversion of seismic intensity data. A large number of seismic intensity data have been accumulated in a uniform scale in the Aegean region, where the seismic activity is much higher than that of the other Mediterranean regions. Nearly 11000 seismic intensity data from 47 earthquakes that have occurred in these regions were used to determine the seismic attenuation structure. The resulting structure reveals a remarkable contrast of attenuation. In the top layer (depth 0-20 km), low Q is dominant in the central Aegean sea, while high Q is dominant in the surrounding land areas, except for Southwestern Turkey. The low-Q regions correspond to areas of Neogene-Quaternary grabens where the high seismicity of shallow earthquakes appears. In the lower layer (20-40 km) low-Q areas are located in the southeastern part of the Hellenic arc. Some low-Q spots corresponding to the distribution of volcanoes exist along the volcanic arc. The low-Q spots might correspond to diapirs causing subduction volcanism.

scholarly journals Evaluating variability in coseismic slips of paleoearthquakes from an incomplete slip history: an example from displaced terrace flights across the Kamishiro fault, central Japan

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Naoya Takahashi ◽  
Shinji Toda
Keyword(s):  
Monte Carlo ◽  
Three Dimensional ◽  
Seismic Hazard Assessment ◽  
Probabilistic Seismic Hazard Assessment ◽  
Reverse Fault ◽  
Central Japan ◽  
Systematic Analysis ◽  
Fluvial Terraces ◽  
Rupture Length ◽  
Slip History

AbstractExamining the regularity in slip over seismic cycles leads to an understanding of earthquake recurrence and provides the basis for probabilistic seismic hazard assessment. Systematic analysis of three-dimensional paleoseismic trenches and analysis of offset markers along faults reveal slip history. Flights of displaced terraces have also been used to study slips of paleoearthquakes when the number of earthquakes contributing to the observed displacement of a terrace is known. This study presents a Monte Carlo-based approach to estimating slip variability using displaced terraces when a detailed paleoseismic record is not available. First, we mapped fluvial terraces across the Kamishiro fault, which is an intra-plate reverse fault in central Japan, and systematically measured the cumulative dip slip of the mapped terraces. By combining these measurements with the age of the paleoearthquakes, we estimated the amount of dip slip for the penultimate event (PE) and antepenultimate event (APE) to be 1.6 and 3.4 m, respectively. The APE slip was nearly three times larger than the most recent event of 2014 (Mw 6.2): 1.2 m. This suggests that the rupture length of the APE was much longer than that of the 2014 event and the entire Kamishiro fault ruptured with adjacent faults during the APE. Thereafter, we performed the Monte Carlo simulations to explore the possible range of the coefficient of variation for slip per event (COVs). The simulation considered all the possible rupture histories in terms of the number of events and their slip amounts. The resulting COVs typically ranged between 0.3 and 0.54, indicating a large variation in the slip per event of the Kamishiro fault during the last few thousand years. To test the accuracy of our approach, we performed the same simulation to a fault whose slip per event was well constrained. The result showed that the error in the COVs estimate was less than 0.15 in 86% of realizations, which was comparable to the uncertainty in COVs derived from a paleoseismic trenching. Based on the accuracy test, we conclude that the Monte Carlo-based approach should help assess the regularity of earthquakes using an incomplete paleoseismic record.

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