Interseismic deformation and earthquake hazard along the southernmost Longitudinal Valley fault, Eastern Taiwan
Journal
Bulletin of the Seismological Society of America
Journal Volume
102
Journal Issue
4
Pages
1569-1582
Date Issued
2012
Author(s)
Abstract
About half of the 8 cm/yr of oblique convergence across the active convergent plate boundaries of Taiwan occurs in eastern Taiwan, across the Longitudinal Valley. Significant shortening and left-lateral slip occurs across the Longitudinal Valley fault there, both as shallow fault creep and as seismogenic fault slip. The southernmost Longitudinal Valley fault comprises an eastern Peinan strand and a western Luyeh strand. We derive an interseismic block model for these two strands using data from a small-aperture Global Positioning System (GPS) campaign and leveling. The model provides estimates of fault slip rates and quantifies slip partitioning between the two strands. A 45 mm/yr dip-slip rate on the northern Peinan strand diminishes southward, whereas the left-lateral component increases. In contrast, nearly pure dip-slip motion of about 20 mm=yr on the southern Luyeh strand diminishes northward to about 8 mm/yr and picks up a component of left-lateral motion of about 15 mm/yr before it dies out altogether at its northern terminus. The Luyeh and the northern Peinan strands record near-surface creep, but the southern Peinan strand appears locked. The potential earthquake magnitude for the two strands may be as high as M w 6.5. We anticipate seismic rupture mainly on the locked portion of the Peinan strand.
Type
journal article