Estimating the Radiated Seismic Energy of the 2010 ML 6.4 JiaSian, Taiwan, Earthquake Using Multiple-Event Analysis

Abstract

Through a proposed multiple-event analysis of teleseismic P-waves, this study investigated the radiated seismic energy and rupture process of the 2010 JiaSian earthquake. Results showed that the earthquake comprised at least two sub-events. The first sub-event was followed by the second sub-event, ~1.7 s later. The entire source duration was 5.4 s. Let the two sub-events occur on the same fault plane with a strike of 304° and a dip of 28°; the first sub-event had a relatively smaller seismic moment (M 0 ) and larger radiated seismic energy (E S ) than the second sub-event, and this leads to the E S /M 0 of the first sub-event larger than that of the second sub-event thus. This feature implies that the first sub-event probably had a higher static stress drop during faulting. The total M 0 was estimated to be 2.17 × 10 18 Nm, corresponding to M W = 6.15, and the total E S was ~2.91 × 10 13 Nm, larger than that estimated only from a single source. Subsequently, the E S /M 0 was approximately 1.3 × 10 -5 , lower than ordinary earthquakes. The low static stress drop was probably responsible for the low E S /M 0 . Overall, the 2010 JiaSian earthquake was characterized by a relatively low E S /M 0 and low static stress drop, and then the partial stress drop model would be relatively appropriate to interpret its rupture process.

Multiple Event Analysis of the 2008 Mw 7.9 Wenchuan Earthquake: Implications for Variations in Radiated Seismic Energy During Faulting

“…The multiple-event analysis reveals more E S during earthquake rupture than from the surface-wave analysis. Such multiple event analysis (Kikuchi and Fukao 1988;Hwang et al 2008, Hwang 2012 seems to decrease the effect of finite-frequency bandwidth on the estimate of E S (Wang 2004). Overall, the E S /M 0 ratio ~1.22 × 10 -4 for the Wenchuan earthquake is larger than those (5 × 10 -5 ) for ordinary earthquakes, and then a rapid drop in friction may occur during earthquake faulting which implies a high rupture velocity (e.g., Kanamori and Heaton 2000).…”

“…Furthermore, the usage of a finite frequency bandwidth in seismic waves would also give rise to an underestimation of E S , due to a lack of high-frequency content (e.g., Wang 2004). The estimation of E S from the source time functions of multiple events (Kikuchi and Fukao 1988;Hwang et al 2008;Hwang 2012) and finite-fault source model (Kanamori 2006) appears to detect a certain amount of high-frequency energy. In spite of the difficulties in estimating radiated seismic energy, the E S /M 0 of strike-slip earthquakes is significantly different from that of reverse or normal earthquakes (e.g., Choy and Boatwright 1995;Pérez-Campos and Beroza 2001).…”

“…(Kikuchi and Fukao 1988;Kanamori 1994;Kanamori and Heaton 2000). In general, radiated seismic energy can either be determined from the integration of seismic waves (e.g., Choy and Boatwright 1995;Hwang et al 2001;Pérez-Campos and Beroza 2001) or source time function (e.g., Vassiliou and Kanamori 1982;Kikuchi and Fukao 1988;Hwang et al 2010Hwang et al , 2012Hwang 2012). Scaled energy, the ratio (E S /M 0 ) of radiated seismic energy (E S ) to seismic moment (M 0 ), is related to the dynamics of earthquake faulting.…”