Seismogenic faults along the major suture of the plate boundary deduced by dislocation modeling of coseismic displacements of the 1951 M7.3 Hualien–Taitung earthquake sequence in eastern Taiwan

Research at plate boundaries generally focuses on the kinematics of plate motions, the genesis of large earthquake, and natural resources. However, often the present state of knowledge is still insufficient to reveal the details of such dynamic systems. To define in more detail the dynamics of, a major plate boundary fault the Coastal Range Fault, eastern Taiwan, we use seismologic and geodetic data to unravel its subsurface geometry and relevant fault behavior. By recomputing the archive triangulation datasets (1917–1978), and using a dislocation algorithm, we determine that it consists of three segments. Our model results are consistent with the observation of the 1951 M7.3 Hualien–Taitung earthquake sequence: that the southern two segments are both oblique-slip faults with significant thrust components, while the northern segment is a pure strike-slip fault. According to our model each segment has the potential to produce an earthquake larger than M7. However, based on GPS observations and seismic records, slip on the southern segment may take the form of aseismic creep and multiple moderate earthquakes, rather than large events with long recurrence interval as occur on the two more northerly segments. With regard to the central segment, the epicenter distribution of catalogued earthquakes occurring after 1951 reveals the presence of a seismic gap, indicating that slip on this segment is predominantly coseismic, with a correspondingly higher potential for large earthquakes in the future.