Evaluation of aftershock hazard of the 2018 M 6.2 Hualien earthquake

Abstract

This paper presents a near real-time evaluation of earthquake hazard after the shallow M L 6.2 Hualien shock of depth 10.6 km occurred 2350 LT, 6 February 2018 at epicenter (24.10°N, 121.73°E). Since a large aftershock intends to bring up a new aftershock sequence, we develop a time-magnitude hazard function for the double aftershock sequences. Note that the double-sequence aftershock hazard model can be regarded as a generalization of the Reasenberg-Jones (RJ) model and hence is denoted by DSRJ. For a near real-time evaluation of the aftershock hazard in the golden window particularly for emergent rescue work, the DSRJ or RJ model is estimated based on early aftershock sequence and then the occurrence rate and number of the forthcoming aftershocks in 3 days after the Hualien main shock are forecasted. Results of a data analysis show that the DSRJ model is better than the RJ model on near real-time assessment of short-term aftershock hazard. This provides an evidence that the aftershocks occurred in a short time after the Hualien main shock may not be a single aftershock sequence.

Understanding the 6 February 2018, Hualien earthquake sequence through catalog compilation

“…On 6 February 2018, an earthquake with a moment magnitude (M w ) of 6.4 hit Hualien, east Taiwan, toppling several buildings and causing more than a dozen casualties Chen et al 2019;Hwang et al 2019;Wen et al 2019). Unlike another hazardous M w = 6.4 earthquake that occurred two years ago in Meinong, Southwest Taiwan (Kanamori et al 2017;Kuo-Chen et al 2017;Lee et al 2017), the 2018 Hualien earthquake was preceded by a prominent foreshock sequence, including a M w = 6.1 event followed by more than 50 events of local magnitude M L ≥ 3.0 within 12 h that migrated southwest and upwards (Fig.…”

Introduction to the special issue on the 2018 Hualien, Taiwan, earthquake

“…Comparisons lead to the conclusions that the high seismicity rate accompanied with a low b-values is indicative of higher potential for events with larger magnitude. Chen et al (2019d) estimated "time-varying" b-values and seismicity rates after the Hualien main shock based on generalized Reasenberg-Jones statistic models. The study attempt to forecast, in near real-time manner, the forthcoming aftershock hazard based on 6-and 12-hr windows after the main shock.…”