Earthquake on April 13, 2025 with MS=5.9, I0=8 in Tajikistan: urgent and updated data

Instrumental and macroseismic data on the Tajikabad earthquake of April 13, 2025 with MS=Mw=5.9, which occurred in the northeast of the Tajik depression, are analyzed. In a number of settlements in the Surkhob River valley, at distances of 7–25 km from the epicenter, the earthquake caused destructive consequences corresponding to 7-point intensity by the SHSI-17 scale (Russian seismic intensity scale, State Standard 57546-2017). The intensity at the epicenter, calculated using the macroseismic field equation with coefficients for the Tajik depression, was I0=8. The earthquake was recorded by nine stationary seismic stations of the Geophysical Service of the National Academy of Sciences of Tajikistan and hundreds stations of various international seismological centers around the world. The earthquake epicenter was found to be confined to the northeastern-trending Yafuch fault, with the orientation and dip of which one of the nodal planes of the focal mechanism coincides. Records of strong ground movements at 44 seismic stations in Central Asia were analyzed. The instrumental intensity at 44 strong motion recording points in Tajikistan and neighboring countries was estimated based on acceleration amplitudes, and in most cases it turned out to be lower than the observed intensity. This may be due to the installation of sensors at bedrock outcrops, which corresponds to category I soils, as opposed to category II and III soils in populated areas. The earthquake was accompanied by an intensive aftershock process: within the week since the main shock, 92 aftershocks with M=2.6–4.7 and many weaker ones were registered and processed. The largest aftershocks were noticeable.