Source-Scaling Relationship for M 4.6-8.9 Earthquakes, Specifically for Earthquakes in the Collision Zone of Taiwan

Abstract

We investigated the source scaling of earthquakes (M w 4.6-8.9), mostly from the Taiwan orogenic belt, and made a global compilation of source parameters to examine the scaling self-similarity. Finite-fault slip models (12 dip-slip and 7 strike-slip) using mainly dense strong-motion data and teleseismic data from Taiwan were utilized. Seven additional earthquakes (M >7) were included for further examination of scaling of large events. We determined the effective length and width for the scaling study was M 0 ∼ L 2 and M 0 ∼ L 3 for the events less than and larger than the seismic moment of 10 20 N m, respectively, regardless of the fault types, suggesting a nonself-similar scaling for small to moderate events and a self-similar scaling for large events. Although the events showed variation in stress drops, with the exception of three events with high stress drops, most of the events had stress drops of 10-100 bars. The observed bilinear relation is well explained by the derived magnitude-area equation of Shaw (2009) when we considered only events with stress drops of 10-100 bars and a seismogenic thickness of 35 km. The bilinear feature of the regressed magnitude-area scaling holds for ruptured areas up to about 1000 km 2 for our seismogenic thickness of 35 km. For the events having rupture areas larger than that, the average slip becomes proportional to the rupture length. The distinct high stress drop events from blind faults in the western foothill of Taiwan yield local high peak ground accelerations (PGAs) when compared to the Next Generation Attenuation model. Regardless of the relative small magnitudes of these events, the high PGAs give the region higher seismic hazard potential and thus require special attention for seismic hazard mitigation.

Hybrid Ground Motion Simulation for the 2013 ML 6.4 Ruisui, Taiwan Earthquake

“…Figure 6 shows the source scaling characteristic analysis result, and both the SMGA and rise time are in good agreement with the scale. Here, we also estimated the stress drop for the SMGA and obtained a value of 10.1 MPa, which is consistent with most earthquakes occurred in Taiwan (Yen and Ma 2011). Wen et al (2014b) suggests that the high stress drop of the two 2013 Nantou earthquakes might be related to immature blind fault.…”

“…On the other hand, because the spectral ratio fitting was applied to the averaged spectral ratio and because we considered the main SMGA, this process might lead to underestimation of the effect of the other asperity. Most earthquakes occurred in Taiwan are moderate-sized events, so we usually could assume one asperity to represent the main faulting feature (Yen and Ma 2011). Since we used the 2013 Ruisui earthquake as a case study to investigate the earthquake source characteristics using broadband strong motion simulation through the hybrid scheme, analysis with multiple SMGAs could be considered for more comprehensive investigations in the future.…”

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

“…Generally speaking, the effective rupture length is shorter than the surface rupture length (cf. Yen and Ma 2011). According to Mai and Beroza (2000), the effective rupture length for the 2008 Wenchuan earthquake is ~240-km-long from the source model of Ji and Hayes (2008), and ~190-km-long from that of Sladen (2008).…”

Earthquake Probability Assessment for the Active Faults in Central Taiwan: A Case Study

“…The number in parentheses is the weight of parameter in logic tree. Wells andCoppersmith (1994) equation andMa (2011) which probability model is used to assess the earthquake probability. The last event times at the Sanyi fault and the Tamaopu-Shuangtung fault are still unknown; the ShihtanTuntzuchiao fault system is 1935 A.D. (M w = 7.1) (Sheu et al 1982;Cheng 1995;Chen and Tsai 2008); the Tachia …”