Case 16: Precursory changes before the Nankai earthquake of 1946, In some precursors prior to recent great earthquakes along the Nankai trough

1991 ◽  
pp. 84-85 ◽  
Author(s):  
H. Sato
Keyword(s):  
Nankai Trough ◽  
Great Earthquakes ◽  
Nankai Earthquake

Estimating the Nankai Trough Megathrust Earthquake’s Anticipated Fiscal Impact on Japanese Governments

2020 ◽  
Vol 15 (5) ◽  
pp. 633-644
Author(s):  
Takeshi Miyazaki ◽  
Shingo Nagamatsu ◽  
◽  
◽  
Keyword(s):  
Local Governments ◽  
Nankai Trough ◽  
Seismic Intensity ◽  
Great East Japan Earthquake ◽  
Fiscal Impact ◽  
Local Public Finance ◽  
Damage Data ◽  
Fiscal Revenue ◽  
The Impact ◽  
Nankai Earthquake

This study estimates the fiscal impact of the anticipated Nankai Trough Megathrust Earthquake on both the national and local Japanese governments to identify their sovereign risk. First, we estimate the impact of the Great East Japan Earthquake on local public finance using panel data regressions on 2008–2015 fiscal data. Second, based on the anticipated damage data – seismic intensity and area of inundation – of the Nankai earthquake and the coefficients derived from the first step, we estimate the amounts of fiscal revenue and expenditures that would be required by every local government for the anticipated Nankai earthquake. Finally, we estimate the fiscal expenditure of the national government in proportion to the estimated local ones. We find that first, the estimated fiscal requirements in the two years after the earthquake are about JPY 161 trillion, 5.9 times those of the 2011 Great East Japan Earthquake. Second, the financial disparity between affected and non-affected local governments is large because the Nankai earthquake would affect more municipalities than the Great East Japan Earthquake. The fiscal burden of non-affected municipalities would be relatively higher. These findings indicate that the Nankai earthquake will not only be a local disaster but also a national catastrophe.

The 1946 Nankai earthquake and segmentation of the Nankai Trough

2002 ◽  
Vol 132 (1-3) ◽  
pp. 75-87 ◽  
Author(s):  
Phil R Cummins ◽  
Toshitaka Baba ◽  
Shuichi Kodaira ◽  
Yoshiyuki Kaneda
Keyword(s):  
Nankai Trough ◽  
Nankai Earthquake

scholarly journals Amplification of tsunami heights by delayed rupture of great earthquakes along the Nankai trough

2010 ◽  
Vol 62 (4) ◽  
pp. 427-432 ◽  
Author(s):  
Kentaro Imai ◽  
Kenji Satake ◽  
Takashi Furumura
Keyword(s):  
Nankai Trough ◽  
Great Earthquakes ◽  
Delayed Rupture

Tsunami scenarios for megathrust earthquakes: mechanics of multi-segment ruptures and elastic-fluid dynamics of wave propagation

2020 ◽  
Author(s):  
Tatsuhiko Saito ◽  
Akemi Noda
Keyword(s):  
Fluid Dynamics ◽  
Strain Energy ◽  
Seismic Waves ◽  
Nankai Trough ◽  
Ocean Bottom ◽  
Bottom Pressure ◽  
Ocean Bottom Pressure ◽  
Megathrust Earthquakes ◽  
Great Earthquakes ◽  
Pressure Changes

<p>Great earthquakes repeatedly occurred with different rupture processes in the Nankai trough, southwestern Japan. The 1944 Tonankai and the 1946 Nankai earthquakes (M ~8) caused serious tsunami damage over many areas along the coastline. The greatest earthquake in this region is the 1707 Hoei earthquake (M 8.4) that is believed to have ruptured the whole region (~600 km) of the Nankai Trough. The purpose of this study is to theoretically assess the tsunami height along the coasts excited by great earthquakes that can possibly occur in future in this region and simulate observable tsunami records during the earthquakes.</p><p>This study employed a new method for making various rupture scenarios. Based on a shear-stress distribution along the plate boundary estimated by the GNSS data analyses (Noda et al. 2018 JGR), we calculated coseismic slip distributions to release the accumulated stress for possible multi-segment rupture scenarios. Then, we used the strain energy released by the rupture to evaluate the possibility of each event. The released strain energy should be larger than the energy dissipated on the fault. However, for some scenarios, the released strain energy was smaller than the dissipated energy under the assumptions of friction laws. Such rupture scenarios are not likely to occur in the viewpoint of earthquake mechanics. This approach can provide necessary conditions of the strain energy or the accumulated stress levels for multi-segment rupture processes, while methods based on empirical or kinematic approaches do not treat stress or interseimsmic stress-accumulation periods required for ruptures.</p><p>Another distinctive point in our approach is that we theoretically synthesize ocean-bottom pressure changes caused by both seismic waves and tsunamis using a simulation method based on elastic and fluid dynamics (Saito and Tsushima 2016 JGR; Saito et al. 2019 Tectonophysics). Seismic wave contributions to ocean-bottom pressure changes are critically important for the synthetics in near-field or inside rupture areas because the seismic waves overlap with tsunami signals and work as noise for real-time tsunami monitoring. The records simulated in this study can be used to examine the monitoring ability of a deep-ocean observation network for megathrust earthquakes and tsunamis in this region.</p>

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