Determining 1D velocity model from local earthquake data in the South Hangay region, central Mongolia

Abstract

One dimensional (1D) velocity models are still widely used for computing earthquake locations at seismological centers. The location accuracy of an earthquake strongly depends on the velocity model used to compute the location. In the past, the local velocity model developed for the Hangay region was lacking precision due to insufficient data. Within the framework of the “Intracontinental Deformation and Surface Uplift- Geodynamic Evolution of the Hangay Dome, Mongolia, Central Asia” project [15], 72 seismic Broadband stations network were deployed in the Hangay Dome. This gives us an opportunity to estimate the crustal velocity structure of the South Hangay region using recorded local earthquake data. For this purpose, available velocity models for the South Hangay region have been re-evaluated. By simultaneous invertion P- and S-wave arrival times using VELEST algorithm, we estimated minimum 1D velocity models, station corrections, hypocentre locations, and origin times for the south Hangay region. Consequently, 1D crustal velocity model is proposed for the South Hangay region. This new model is expected to improve the accuracy of the routine hypocenter determination and as initial reference models for seismic tomography study.

Crustal architecture of a metallogenic belt and ophiolite belt: implications for mineral genesis and emplacement from 3-D electrical resistivity models (Bayankhongor area, Mongolia)

“…However, this feature does not appear to be strong and does not appear to be connected to the surface trace of the fault. This region has had recent seismic activity, including earthquake events of magnitude > 4 since 2012 (Dashdondog et al 2020;Welkey et al 2018;Adiya et al 2003; see Fig. 1c).…”

“…b The survey area in a regional context. c Distribution of recent seismicity (2012 to 2014; data from Dashdondog et al 2020) mostly to the Permian or late Palaeozoic (Jargalan et al 2007;Jargalan and Fujimaki 2000;Watanabe et al 1999). They may correspond temporally to melting or magmatic events after subduction when a high regional compressional stress was present, possibly a critical component, due to the collisional deformation of the Baydrag microcontinent (Watanabe et al 1999).…”

“…6 has heightened seismicity (see Fig. 1c), typically occurring at depths of 5 km to 15 km (see Dashdondog et al 2020), that may be attributed to small, reactivated faults and pre-existing weaknesses within the metamorphic belt, which facilitated previous metasomatism. It should be noted that ruptures along faults lead to enhanced permeability (e.g., Sibson 2020).…”

“…b The survey area in a regional context. c Distribution of recent seismicity (2012 to 2014; data fromDashdondog et al 2020)…”

25,000 Years Long Seismic Cycle in a Slow Deforming Continental Region of Mongolia

“…[18][19][20]. In contrast, the deformation appears more distributed in the Hangay dome 21 , a region where faults are sometimes only evidenced by the seismic activity [22][23] .…”