[S-SS05] Advancements in Regional Seismic Networks: Operations, Applications, and Development

[SSS05-03] Broadband seismic observations and imaging of the crust and uppermost mantle beneath Northern Vietnam

*Ha Vinh-Long^1,2,3,5, Hsin-Hua Huang^2,4, Kuan-Fu Feng⁶, Yun-Ze Cheng⁷, Bor-Shouh Huang², Le-Minh Nguyen⁵, Van-Duong Nguyen⁵, Tu-Son Le⁵, Tien-Hung Nguyen⁵, Quoc-Van Dinh⁵, Thi-Giang Ha⁵, An-Nguyen Tran⁵, Quang-Khoi Le⁵ (1.Taiwan International Graduate Program Earth Sciences System (TIGP-ESS), Academia Sinica, Taiwan, 2.Institute of Earth Sciences, Academia Sinica, Taipei City, Taiwan, 3.National Central University, Taoyuan City, Taiwan, 4.Department of Geosciences, National Taiwan University, Taipei City, Taiwan, 5.Institute of Geophysics, Vietnam Academy of Science and Technology, Ha Noi, Vietnam, 6.Department of Earth and Space Sciences, University of Washington, Seattle, WA 98195-1310, US, 7.Research School of Earth Sciences, Australian National University, Canberra, ACT, Australia)

Keywords:Seismic tomography, MCMC inversion, Northern Vietnam, Red River Shear Zone, Crustal heterogeneity.

The extrusion tectonics resulting from the collision between the Indian and Eurasian plates has driven complex and multi-phase geological activity in Northern Vietnam. This process has led to the formation of major tectonic features, including the Ailao Shan–Red River Shear Zone, which extends from Tibet to the Tonkin Gulf (Tapponnier et al., 1986; Leloup et al., 1995), and the Ailao Shan–Song Ma Suture (Hutchison, 1989; Thanh et al., 1996; Zhang et al., 2013; Faure et al., 2014). However, the precise location of the plate boundary e.g. the major boundary between South China and Indochina plates, whether along the Song Ma Suture or the Red River Fault, remains a subject of debate. Despite extensive geological and geophysical investigations, the detailed crustal architecture of this region remains poorly constrained, limiting our understanding of its tectonic evolution.
In recent decades, the development of modern seismic networks has provided new opportunities to study the crustal structure of Northern Vietnams (Huang et al., 2013; Nguyen et al., 2013; Legendre et al., 2015; Qiao et al., 2018; Yang et al., 2021; Ha et al., 2024). In this study, we present a summary of the development and implementation of a broadband seismic network in Northern Vietnam, designed for earthquake monitoring and imaging of crustal and mantle structures. This network provides critical dataset for reassessing the tectonic evolution of the Red River Shear Zone and surrounding areas and seismic hazards in the northern Vietnam. We present new insights into the tectonic boundary between the South China and Indochina plates as well as high-resolution crustal heterogeneity across the Red River Shear Zone, derived from seismic tomography and Bayesian Markov Chain Monte Carlo (MCMC) inversion methods. Additionaly, we outline future directions for expanding the national seismic network and highlight resent research advancements in the northern Vietnam.