A Comparative Study of Source Complexity of Two Moderate-Sized Earthquakes in Southern Taiwan: 2016 Mw6.4 and 2010 Mw6.2 Earthquakes

We study the complex rupture history of the 2016 Mw6.4 Meinong earthquake and the 2010 Mw6.2 Jiaxian earthquake in southern Taiwan by simultaneously inverting near-field strong-motion records, local and teleseismic broadband waveforms along with long-period surface waves. The focal mechanism results reveal that both earthquakes may rupture two different blind faults. The rupture of the 2016 event is dominated by the strike-slip motion with minor thrust faulting, while the 2010 event is a relatively high-angle thrust earthquake. Our preferred finite-fault source models suggest that the coseismic rupture history of the 2016 event should be relatively more complex than the 2010 event. During the 2016 event, two main patches of slip characterize the coseismic slip history. The cumulative seismic moment within 12 s of rupture is about 5.36 × 10 18 N m, which is 1.9 times of the moment of the 2010 event. The slip of the 2016 event is associated with relatively larger perk slip of 0.7 m at shallower depth (~18–19 km), higher average slip of 0.3 m and faster slip rate with the maximum value of 3.4 m/s. Our kinematic models can shed some light on the cause of the difference in seismic hazard between these two earthquakes, and will be further applied to analyze the deep blind fault structure in southern Taiwan.