scholarly journals High‐density seismic refraction imaging of plate boundary structures in the slow earthquake gap zone off western Kii Peninsula, Nankai Trough

2020 ◽  
Author(s):  
Yanfang Qin ◽  
Gou Fujie ◽  
Shuichi Kodaira ◽  
Yasuyuki Nakamura ◽  
Yuka Kaiho ◽  
...  
Keyword(s):  
Nankai Trough ◽  
Seismic Refraction ◽  
Plate Boundary ◽  
High Density ◽  
Kii Peninsula ◽  
Slow Earthquake

scholarly journals In-situ mechanical weakness of subducting sediments beneath a plate boundary décollement in the Nankai Trough

2018 ◽  
Vol 5 (1) ◽  
Author(s):  
Yohei Hamada ◽  
Takehiro Hirose ◽  
Akira Ijiri ◽  
Yasuhiro Yamada ◽  
Yoshinori Sanada ◽  
...  
Keyword(s):  
Nankai Trough ◽  
Plate Boundary

The significance and tectonic evolution of Huatung basin

2020 ◽  
Author(s):  
Minghui Zhao ◽  
Jean-Claude Sibuet ◽  
Jonny Wu ◽  
Longtao Sun ◽  
Jiazheng Zhang
Keyword(s):  
Seismic Refraction ◽  
Plate Boundary ◽  
Philippine Sea Plate ◽  
Plate Boundaries ◽  
Manila Trench ◽  
Shear Plate ◽  
Second Fracture ◽  
Tectonically Active ◽  
Seismic Refraction Survey ◽  
Early Cenozoic

<p>The Huatung basin (HB), located between the Philippine Sea plate (PSP) and the South China Sea (SCS), has likely existed near tectonically-active plate boundaries since the early Cenozoic. It may record SCS evolution from the SCS rifting phase to today, and is a key region to understand the broad geodynamic interactions between the SCS and PSP. A left-lateral shear plate boundary between the SCS and PSP followed the Gagua ridge and was active before 56 Ma. A slight compressive component along the Gagua ridge might have occurred from 40 to 30 Ma, giving rise to the topographic uplift of Gagua ridge and adjacent ridges with possibly some underthrusting of the PSP below the HB. A significant compressive episode also occurred along a second fracture zone around 23 Ma ago. The Manila trench inception occurred along the PSP-SCS plate boundary before the end of SCS spreading, involving the subduction of the younger SCS beneath the older HB. Later the intra-oceanic Luzon arc formed and collided in a sub-parallel fashion with the Eurasian continent around 5-6 Ma ago to form Taiwan. The PSP/EU motion was oblique with respect to this plate boundary during SCS opening. However, we have no direct evidence of the HB age (early Cenozoic or early Cretaceous) and if the PSP underthrusted below the HB. We propose to carry a deep seismic refraction survey and dredge sampling of basement units to clarify this problem. This work is supported by the Chinese National Natural Science Foundation (contracts 91958212, 41730532, 41576070 and 41676043).</p>

Quest for Fluid Flow along the Gloria Fault – First results of R/V Meteor expedition 162

2020 ◽  
Author(s):  
Christian Hensen ◽  
Pedro Terrinha ◽  
Joāo Duarte ◽  
Norbert Kaul ◽  
Mark Schmidt ◽  
...  
Keyword(s):  
Fracture Zone ◽  
Seismic Refraction ◽  
Plate Boundary ◽  
Thick Layer ◽  
Deep Ocean ◽  
Transform Faults ◽  
Tectonic Processes ◽  
Exchange Processes ◽  
First Results ◽  
Potential Fluid

<p>Vast areas of the deep ocean floor are still insufficiently explored with respect to tectonic processes, exchange processes between the lithosphere and the ocean, and potential deep chemosynthetic energy sources for life. Transform faults and fracture zones, which are dominant seafloor morphological features in the abyssal ocean, deserve specific attention in this regard as they provide potential pathways for fluid recycling. One of them is the Gloria Fault, a unique feature in the Central North Atlantic. It has been the source of large magnitude earthquakes (namely the 1941, M8.4, the second largest instrumental earthquake on a fracture zone) and is a special case of a plate boundary, corresponding to the transform reactivation of an old oceanic fracture zone. Seismic refraction has shown an anomalous layer between normal lower crust and uppermost mantle, possibly a 4 km thick layer of hydrated mantle. We present first results of RV Meteor cruise M162 (March-April 2020) dedicated to the groundtruthing of potential fluid emanation sites.</p>

scholarly journals Capability of Tokai Strainmeter Network to Detect and Locate a Slow Slip: First Results

2019 ◽  
Vol 177 (6) ◽  
pp. 2701-2718
Author(s):  
K. Z. Nanjo
Keyword(s):  
Nankai Trough ◽  
Plate Boundary ◽  
Historical Records ◽  
Slow Slip ◽  
Dense Network ◽  
Magnitude Of Completeness ◽  
First Results ◽  
Seismic Networks ◽  
Eastern Half ◽  
Tokai Region

AbstractThe Tokai Strainmeter Network (TSN), a dense network deployed in the Tokai region, which is the easternmost region of the Nankai trough, has been designed to monitor slow slips that reflect changes in the coupling state of the plate boundary. It is important to evaluate the current capability of TSN to detect and locate slow slips. For this purpose, the probability-based magnitude of completeness developed for seismic networks was modified to be applicable to the evaluation of TSN’s performance. Using 35 slow slips having moment magnitudes M5.1–5.8 recorded by TSN in 2012–2016, this study shows that the probability that TSN detected and located a M5-class slow slip is high (> 0.9) when considering a region in and around the TSN. The probability has been found to depend on the slip duration, especially for M5.5 or larger, namely the longer the duration, the lower the probability. A possible use of this method to assess the network’s performance for cases where virtual stations are added to the existing network was explored. The use of this application when devising a strategic plan of the TSN to extend its coverage westwards is proposed. This extension that allows TSN to cover the entire eastern half of the Nankai trough is important, because the historical records show that the eastern half of this trough tends to rupture first.

Real-Time Tsunami Prediction System Based on Seafloor Observatory Data Applied to the Inland Sea, Japan

2018 ◽  
Vol 52 (3) ◽  
pp. 120-127 ◽  
Author(s):  
Narumi Takahashi ◽  
Kentaro Imai ◽  
Kentaro Sueki ◽  
Ryoko Obayashi ◽  
Masanobu Ishibashi ◽  
...  
Keyword(s):  
Real Time ◽  
Local Governments ◽  
Nankai Trough ◽  
Plate Boundary ◽  
Maximum Height ◽  
Prediction System ◽  
Worst Case ◽  
Reflected Waves ◽  
Arrival Times ◽  
Tsunami Waveforms

AbstractThe damage and loss of life caused by tsunamis can be reduced by timely warnings, which predict the arrival time and maximum height of tsunamis, to support evacuations and other mitigating actions. We have developed a real-time tsunami prediction system based on data from the Dense Oceanfloor Network system for Earthquakes and Tsunamis (DONET) that has been implemented in some local governments along the Pacific coast of Japan. The system generates estimates of tsunami arrival times and the height, inundation areas, and worst case using selected fault rupture models. The main objective of this paper is to show the possibility of applying the above system for a complicated topography area, and we report a successful application of the system in Sakaide, a city on the Shikoku coast of the Inland Sea, using a simulated great plate-boundary earthquake in the Nankai Trough. The simulated tsunami propagates to Sakaide by complicated routes between several islands. According to calculated tsunami waveforms of 1,506 cases, waveforms of tsunamis propagating to the Inland Sea have a relatively uniform frequency, regardless of the magnitude of the causative event, after running through the narrow straits in the Inland Sea. At the same time, waves are amplified as they pass between the islands of Shodoshima and Shikoku by an interaction with reflected waves. These effects are compatible with this prediction system, and we confirmed that our predicted tsunami is consistent with the final result from a model of a magnitude 9 Nankai Trough earthquake.

Dense Ocean Floor Network for Earthquakes and Tsunamis Around the Nankai Trough Mega Thrust Earthquake Seismogenic Zone in Southwestern Japan: Real Time Monitoring of the Seismogenic Zone

2008 ◽  
Author(s):  
Yoshiyuki Kaneda ◽  
Katsuyoshi Kawaguchi ◽  
Eiichiro Araki ◽  
Hiroyuki Matsumoto ◽  
Takeshi Nakamura ◽  
...  
Keyword(s):  
Real Time ◽  
Nankai Trough ◽  
Ocean Floor ◽  
Seismogenic Zone ◽  
Network System ◽  
Real Time Monitoring ◽  
Broadband Seismometer ◽  
Kii Peninsula

The Nankai Trough is well known as the mega thrust earthquake generating tsunamis, with the interval of 100–150 years. The 1944 Tonankai and the 1946 Nankai earthquakes around the Nankai trough, each hypocenter was located off the Kii peninsula. Based on structural and simulation researches, we proposed and have been starting to deploy the dense ocean floor observatory network system around the Tonankai seismogenic zone, to monitor crustal activities using broadband seismometer, accelerometer and precise pressure gauges. The ocean floor network is significant ant important to monitor the crustal activities around mega-thrust earthquakes.

Sign in / Sign up

Export Citation Format

Share Document