A. Dobrynina¹ , A. Sorokin² , V. Sankov¹ , V. Chechelnitsky³ , E. Chernykh¹ , L. Tsidipova⁴ , T. Tubanov⁴ , V. German⁵ , U. Munkhuu⁶

¹Institute of the Earths Crust, Siberian Branch of Russian Academy of Science, Russian Federation
²Institute of Solar-Terrestrial Physics, Siberian Branch of Russian Academy of Science, Russian Federation
³Geophysical Service of the Russian Academy of Sciences, Baikal, Russian Federation
⁴Geological Institute, Siberian Branch of the Russian Academy of Sciences, Ulan-Ude, Russian Federation
⁵Krasnoyarsk Research Institute of Geology and Mineral Resources, Krasnoyarsk, Russian Federation
⁶Institute of Astronomy and Geophysics of the Mongolian Academy of Sciences, Ulaan Bataar, Mongolia

Abstract:

Seismoacoustic effects of the Khubsugul earthquake of December 5, 2014 (51.37N, 100.63E, MW=4.9) were studied. The earthquake occurred in the Khubsugul basin at 3 km depth. An acoustic signal was registered by the infrasound station "Tory" located 175 km from the epicenter; the travel time of acoustic waves is about 280 s. The apparent velocity of infrasound signal propagation is ~625 m/s. We assumed that the epicentral area may not be the acoustic wave radiation source and modelled the signal partly as seismic and partly as acoustic. For the calculations, the velocity of acoustic waves was assumed to be 300 m/s, and of surface waves 3.2 km/s. According to the calculations, the propagation of acoustic waves in the atmosphere are expected up to 80-85 km from the receiver. On the trace "source-receiver" these distances correspond to the northern slope of the Khamar-Daban ridge (southern board of the Turan depression). The difference in height here is 1700 meters. It can be concluded that an infrasound signal was radiated by the slope of the mountain ridge, and that the high apparent velocity of acoustic waves is explained by the fact that the signal is propagated in the crust as a seismic signal.