An analysis on the artificial events in Umnugovi area, Mongolia

Through a cooperation between Korea Institute of Geoscience and Mineral Resources (KIGAM) and Institute of Astronomy and Geophysics (IAG), a seismo-acoustic array was installed in Umnugovi area of the southern Govi, Mongolia in September, 2025 for studying regional earthquakes. The study area experienced two big magnitude earthquakes in 1903 and 1960. The magnitude of the former event was 7.5 and the later one was 7.0. Since the 1903 event occurred, lots of small and middle magnitude events have struck the area but the calculation for attaining precise information of seismic parameters such as epicenter, depth of event, origin time, magnitude was partially limited due to poor seismic network in the area. As an initial step to constrain the solutions for the parameters, a single array process is applied with a seismo-acoustic array named HEXAR which is composed of 10 seismometers, 4 Chaparral M21 acoustic sensors, and hose arrays for reducing background wind noise. HEXAR consists of a relatively large array of 2 km aperture as a hexagonal shape and a small seismo-acoustic array of 0.5 km-aperture inner triangular shape. The Progressive Multi-Channel Correlation (PMCC) method is used for the detection and analysis of regional earthquakes and artificial events. For a preliminary stage of the analysis, separating artificial events from natural earthquakes is processed with a discriminant utilizing short period Rayleigh wave and infrasound signal. In this study, clear features of man-made events from two mines in Umnugovi area is presented with the analysis on the detected Rg phase, infrasound signal and epicenter.