Preparations for the Coming Large Earthquakes at the Nankai Trough. The Influence of Philipine Sea Plate Structure on Great Nankai Trough Earthquakes Inferred from the Rupture Process of the 1946 Nankai Earthquake.

Earthquakes occur in a complex hierarchical fault system, meaning that a realistic mechanically-consistent model is required to describe heterogeneity simply and over a wide scale. We developed a simple conceptual mechanical model using fractal circular patches associated with fracture energy on a fault plane. This model explains the complexity and scaling relation in the dynamic rupture process. We also show that such a fractal patch model is useful in simulating longterm seismicity in a hierarchal fault system by using external loading. In these studies, an earthquake of any magnitude appears as a completely random cascade growing from a small patch to larger patches. This model is thus potentially useful as a benchmarking scenario for evaluating probabilistic gain in probabilistic earthquake forecasts. The model is applied to the real case of the 2011 Tohoku-Oki earthquake based on prior information from a seismicity catalog to reproduce the complex rupture process of this very large earthquake and its resulting ground motion. Provided that a high-quality seismicity catalog is available for other regions, similar approach using this conceptual model may provide scenarios for other potential large earthquakes.

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

Journal of Disaster Research ◽

10.20965/jdr.2020.p0633 ◽

2020 ◽

Vol 15 (5) ◽

pp. 633-644

Author(s):

Takeshi Miyazaki ◽

Shingo Nagamatsu ◽

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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.

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