Source mechanisms of the 1944 Tonankai and 1946 Nankaido earthquakes: Spatial heterogeneity of rise times

Abstract

Kanarnori [ 1972].

Rupture process of the 1944 Tonankai earthquake (Ms 8.1) from the inversion of teleseismic and regional seismograms

“…This estimate is within the range of M s 8.0–8.3 estimated from surface waves by Kanamori [1972] and M j 8.0 and comparable with the M L 8.3 obtained by Richter [1958]. Recent inversions of combined tsunami waveforms and geodetic data by Kato and Ando [1997] and Tanioka and Satake [2001] resulted in seismic moment estimates of 2.0–2.8 × 10 28 dyn cm ( M w 8.2–8.23).…”

“…A large 4.48‐m slip patch on the shallow portion of the southeast edge has a risetime of 9 min, which cannot be resolved with seismic records due to its extremely long risetime. Kato and Ando [1997] attributed this to a relaxation barrier that may have stopped or slowed rupture. The fit between the synthetic and observed tsunami waveforms and the geodetic deformation in the Kato and Ando study are not markedly improved, with only 12% variance reduction.…”

“…In this study, we combined teleseismic and regional strong ground motion data sets including additional regional records from stations at Murotomisaki, Mishima, Funatsu, and Tokyo. Previous geophysical studies [e.g., Satake , 1993; Kato and Ando , 1997; Tanioka and Satake , 2001] inverted geodetic and tsunami waveforms for estimating the static slip distribution of the 1944 Tonankai earthquake. Interpretation of the leveling and triangulation data [e.g., Kanamori , 1973; Ando , 1975a; Saigiya and Thatcher , 1999] in the region of the 1944 Tonankai earthquake is complicated by the fact that the region was not resurveyed until after the 1946 Nankaido earthquake ( M s 8.2).…”

Implications of the 26 December 2004 Sumatra–Andaman Earthquake on Tsunami Forecast and Assessment Models for Great Subduction-Zone Earthquakes

“…Mean slip is identical to the case of Figure 5, such that M w 9.14. excess moment release (reckoned to 1 day after the earthquake) for the 2004 Sumatra-Andaman earthquake in comparison to seismic moment estimates. There have been suggestions from studies of previous earthquakes that short-term afterslip may occur at time periods that affect tsunami generation (Kikuchi et al, 1993;Heki and Tamura, 1997;Kato and Ando, 1997;Mazzotti et al, 2000;Miyazaki et al, 2004). For tsunami earthquakes in particular, long source duration is often ascribed to both anomalously low rupture velocities and slow slip rates (Kanamori, 1972;Kikuchi and Kanamori, 1995).…”

Source rupture processes of the 1944 Tonankai earthquake and the 1945 Mikawa earthquake derived from low-gain seismograms

“…It seems likely that the strong motion records reflect the much shorter period component of the fault slip than that affecting the tsunami generation. Kato and Ando (1997) analyzed the tsunami data considering the finite rise time of the crustal motion, and found that a large tsunami with a rise time of as long as a few minutes was excited around the Atsumi peninsula. This region is just outside the coseismic slip region (asperity) obtained in the present analysis.…”