Mass determination of moment magnitudes Mw and establishing the relationship between Mw and ML for moderate and small Kamchatka earthquakes

Abstract

The average relationship is established between the basic magnitude for the Kamchatka regional catalog, M_L, and modern moment magnitude M_w. The latter is firmly tied to the value of the source seismic moment M₀ which has a direct physical meaning. M_L magnitude is not self-reliant but is obtained through the conversion of the traditional Fedotov’s S-wave energy class, K_S1,2^F68. Installation of the digital seismographic network in Kamchatka in 2006–2010 permitted mass estimates of M₀ and M_w to be obtained from the regional data. In this paper we outline a number of techniques to estimate M₀ for the Kamchatka earthquakes using the waveforms of regional stations, and then compare the obtained M_w estimates with each other and with M_L, based on several hundred earthquakes that took place in 2010–2014. On the average, for M_w = 3.0–6.0, M_w = M_L–0.40; this relationship allows obtaining M_w estimates (proxy-M_w) for a large part of the regional earthquake catalog with M_L = 3.4–6.4 (M_w = 3.0–6.0).