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

该奖项支持研究撞击测深特征对所罗门和新赫布里底俯冲带等地观测到的地震周期和长期隆升和沉降周期之间关系的影响。本课题以数值实验为基础。将使用一个强大的、自适应的、多维的有限元方法求解器Dynethsol2D/3D来完成该项目，以适应大的空间(长达400公里)和时间(长达105年)的尺度。该项目将在台湾的学术中心举行，由Dynethsol2D/3D的主要贡献者之一Tan Eh博士指导。初步结果不仅有助于改善科学界对构造观测的解释。它们还将帮助官员进行长期的地震/海啸预测，以及在苏门答腊岛、所罗门和具有类似地质背景的地区准备和减轻随后的灾害。弹性应变积累、释放和汇聚边缘较长期构造变形的地震周期之间的关系仍然知之甚少。导致俯冲带地形变化的非弹性应变的长期积累被认为是在多个地震周期中发生的。然而，尽管在孕震带上同震释放滑移的机制已经很清楚，但应变在地震间积累的方式，导致俯冲带弧前区域的长期变形，仍然是一个有争议的问题。此外，当随着时间的推移整合在一起时，同震隆起与所罗门和新赫布里底弧前地区等地较长期的垂直形变很难匹配，在这些地区，大的测深特征正在海沟被俯冲。基于这一点和类似的观测，可以推断，同震滑动并不是控制前弧长期形变过程的唯一机制。该项目将对同震滑动和长期形变如何在俯冲带上存在大的凹凸体的情况下在俯冲带累积和相互作用进行数值研究。这一NSF EAPSI奖项支持一名美国研究生的研究，并与台湾科技部合作提供资金。

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.