South Tien Shan Earthquake on January 22, 2024, Mw = 7.0: Filling a Seismic Gap?

On January 22, 2024, an earthquake with Mw = 7.0 occurred in the Southern Tien Shan in the Kyrgyzstan-China border region. The article presents an analysis of the previous seismicity of the region based on homogeneous seismological (global earthquake and focal mechanisms catalogues) and seismotectonic data (active fault global database). The aftershock sequence is also studied using regional data. It is shown that the focal area of the earthquake on January 22, 2024 partially filled the previously existing seismic gap and the gap in the active fault system. The aftershock sequence is intense, although without a pronounced strong aftershock. The aftershock mechanisms are almost identical with the main shock mechanism. According to regional data, there is a deficit of strong aftershocks (mb ≥ 4.8). Whether this indicates the “incompleteness” of the seismic process or not, cannot be assessed based on just six months of data. The change in the number of aftershocks over time shows that after a month and a half after the main shock, the decay of the aftershock process slowed down. This may be due to both seismic activities reaching a long-term level and the redistribution of stresses in the focal area. As a rule, active fault maps serve as a seismotectonic basis for assessing seismic hazard. In this case, a strong earthquake occurred where no documented active faults were noted — it rather extended an existing fault, on the edge of which a cluster of earthquake foci had previously been noted. The question arises as to how reliable are seismic hazard assessments, the seismotectonic basis of which are mapped active faults.

strong earthquakes, seismotectonics, earthquake focal mechanism, aftershocks