Analysis on relocation and focal mechanism of the Chengde ML3.6 earthquake on June 17, 2021

Abstract

On June 17, 2021, an ML3.6 earthquake occurred in Shuangqiao District, Chengde City, Hebei Province. Based on the data of Hebei regional digital seismic network, the double-difference location algorithm was used to reposition the earthquake sequence and a precise epicenter distribution was obtained. The fault plane parameters of this earthquake were computed using the small event fitting method as follows, strike 63.76° and dip 70.52°. The main shock’s optimal unit source time function, moment tensor solution, and double couple solution are obtained by CAP method. Among them, the best fault plane solution is strike 63.4° and dip 52.8°. Based on the fault center solution calculations, the final fault plane parameters were determined to be strike 63.59° and dip 61.66°, which aligns with the region’s Shuangtashan-Shuangfengsi fault. Considering regional tectonic characteristics, it is postulated that this earthquake may have been induced by the principal stress squeezing on the fault, representing a typical normal fault activity. This study provides crucial evidence for identifying the seismogenic structure of the Chengde earthquake and the stress field status in the area.

Keywords

• chengde ml3.6 earthquake
• focal mechanism
• double-difference location
• seismogenic structure