EAPSI: The Effect of Asperities on Geological Properties and Forearc Topography at Subduction Region

Tong Xinyue, Austin TX

Investigators

Abstract

This award supports research to study the effects of impinging bathymetric features on the relationship between seismic cycle and long-term uplift and subsidence cycles observed in places such as the Solomon and New Hebrides subduction zones. This project is based on numerical experiment. A robust, adaptive, multi-dimensional, finite element method solver, Dynearthsol2D/3D, will be used to accomplish the project in order to accommodate large spatial (up to 400 km) and time (up to 105 years) scales. This project will take place at Academic Sinica, Taiwan, under the mentorship of Dr. Tan Eh, one of the major contributor to Dynearthsol2D/3D. The preliminary results will not only help to improve explanations of tectonic observations within the scientific community. They will also help officials with long-term earthquake/tsunami prediction as well as preparation and mitigation of subsequent hazards in Sumatra, Solomon, and regions with similar geological settings. The relationship between the earthquake cycle of elastic strain accumulation, release and longer-term tectonic deformation at convergent margins is still poorly understood. Long-term accumulation of inelastic strain that results in topographic changes at subduction zones is believed to occur over multiple earthquake cycles. However, while the mechanism releasing slip co-seismically on the seismogenic zone is well understood, the way strain accumulates interseismically, causing long-term deformation in the forearc region of subduction zones, is still a matter of debate. Moreover, when integrated over time, coseismic uplift poorly matches the longer-term vertical deformation in places such as the Solomon and New Hebrides forearc regions where large bathymetric features are being subducted at the trench. Based on this and similar observations, it is inferred that coseismic slip is not the only mechanism dominating the long-term deformation processes at forearcs. This project will investigate numerically how coseismic slip and long-term deformation accumulate and interact at subduction zones with the presence of large asperities at the subduction interface. This NSF EAPSI award supports the research of a U.S. graduate student and is funded in collaboration with the Ministry of Science and Technology of Taiwan.