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A scaling law for seismic moment and maximum seismic interval in Japan

Citation

Ji, Yingfeng; Yoshioka, Shoichi (2017), A scaling law for seismic moment and maximum seismic interval in Japan, DataONE Dash, Dataset, https://doi.org/10.15146/R30M3W

Abstract

Seismic periodicity and its magnitude spectrum have been widely studied, but key details remain unclear, such as how these factors relate to earthquake mechanisms. A large number of recorded events in Japan show that in the densely distributed seismogenic zones, the logarithm of the maximum seismic interval (MSI) is roughly proportional to the logarithm of the seismic moment. The recorded M5+ earthquakes preferentially occur at plate convergence zones, where a large seismic moment rate exists. We therefore present a scaling law between the seismic moment and MSI, in which the scale coefficient is likely determined by the seismic moment rate as a product of the loading rate, rigidity, and fault characteristic length.

Methods

To study the 3-D spatial relationship between adjacent hypocenters, we used the seismicity density sphere (SDS), which has been similarly applied in previous b-value analyses (e.g., Guila et al., 2016). The SDS is simply defined as a 3-D sphere zone (Gulia et al., 2016), in which the detected events are collected and counted. The time period from the JMA catalog from 1997 to February 28th, 2015 excluding the tectonic tremors was analyzed, including 1.8 million events occurring between a longitude of 132°E and 147°E and a latitude of 32°N and 46°N. Most of the recorded seismic magnitudes determined by JMA are considered to be almost equivalent to a moment magnitude for seismicity shallower than 60 km (Utsu, 1983; Katsumata, 1996). The center of the SDS is the hypocenter of one of the numerous recorded events. We assumed the radius of the SDS was 10 km considering that the rupture length for an earthquake (M<5) is generally <5 km, and thus, we included only M<5 earthquakes in our SDSs. Among them, the top seismically active 49 SDSs, with at least 2000 events during the period from 1997 to February 28th, 2015, were determined, as shown in Fig. 1 and Table S1. The distances between these SDSs are prescribed to be larger than 0.5 degrees in longitude and latitude.

Usage Notes

Please see the readme.txt.

Funding

JSPS KAKENHI Grant, Award: 16H04040

JSPS KAKENHI Grant, Award: 16H06477