Changes in paleostress and its magnitude related to seismic cycles in the Chelung‐pu Fault, Taiwan

Abstract

Paleostress analysis was conducted through a multiple stress inversion method using slip data recoded for the core samples from the Taiwan Chelung-pu Fault Drilling Project (TCDP). Two stress fields were obtained; one of these had horizontally plunging σ 1 , and the other has horizontally plunging σ 2 or σ 3 in the compressional stress direction of the Chi-Chi earthquake. Stress magnitude for both the stress fields was constrained by stress polygons, which indicated larger SHmax for horizontally plunging σ 1 than that in the case of horizontally plunging σ 2 or σ 3 . These differences in stress orientations and stress magnitude suggest that the change in stress filed can be caused by stress drop and stress buildup associated with seismic cycles. The seismic cycles recoded in the core samples from TCDP could include many events at geological timescale and not only the 1999 Chi-Chi earthquake.

Temporal stress variations along a seismogenic megasplay fault in the subduction zone: An example from the Nobeoka Thrust, southwestern Japan

“…The temporal changes in stress state that we observed along the Nobeoka Thrust are similar to those reported along other active fault zones, including the Chelungpu Fault after the 1999 Chi‐Chi Earthquake (Hashimoto, Tobe, Yeh, & Song, ) and the plate boundary fault in the Japan Trench after the 2011 Tohoku‐Oki Earthquake (Hasegawa et al, ; Lin et al, ). These stress changes are thought to occur as a result of stress drops after earthquakes.…”

Variations in stress and driving pore fluid pressure ratio using vein orientations along megasplay faults : Example from the Nobeoka Thrust, Southwest Japan

“…The temporal stress changes are similar to those shown along other active fault zones, including the Chelungpu Fault after the 1999 Chi‐Chi Earthquake, Taiwan (Hashimoto et al . ).…”

Paleo-stress orientations and magnitudes from triaxial testing and stress inversion analysis in Nankai accretionary prism sediments

“…Constraints on paleo-stress magnitude were derived using the same method as applied by Hashimoto et al (2015), combining the paleo-stress from core-scale fault inversion and from stress polygons. The relationship between stress ratio and friction limit is expressed as…”

“…Paleo-stress can be constrained for faults of unknown age by stress (or alternatively strain) inversion methods (e.g., Angelier 1984;Yamaji 2000). At the Nankai subduction zone, this has been done for older, exhumed parts of the accretionary wedge (Hashimoto et al 2014(Hashimoto et al , 2015 revealing the predominance of normal faulting at the deeper structural level of the Cretaceous accretionary wedge. Lewis et al (2013) examined the paleo-stress state in the shallow Nankai accretionary wedge by inverting core-scale faults in paleomagnetically reoriented cores.…”

“…They found stress geometries indicative of normal faulting, but also strike-slip and thrust faulting in the shallow portion of the accretionary wedge. Hashimoto et al (2015) employed a stress polygon approach that has been used to constrain modern accretionary wedge stress magnitudes (Zoback et al 2003), to determine paleo-stress magnitude in cores recovered from the Chelungpu Fault drilling project in Taiwan. They found that normal faulting regimes were characterized by smaller stress magnitudes than those of reverse faulting regimes.…”