A summary of seismic activities in and around China in 2021

In this article,we review the general characteristics of seismicity in and around China and the overall statistics of earthquake damage in 2021,focusing on several significant events and related scientific topics.Among them,the largest event is the MS7.4 Madoi earthquake in Qinghai Province,northwest China.The event marks another MS≥7 earthquake occurring near the boundary of the Bayan Har Block that has ended a remarkable quiescence of the MS≥7 earthquakes within the Chinese mainland.In addition,the MS6.4 Yangbi earthquake in Yunnan Province,southwest China draws the most attention because of its abundant foreshocks,which are well recorded by the densely distributed seismic stations in the surrounding regions.Regarding this event,we review several recent publications focusing on the Gutenberg-Richter b-value change and the physical mechanism of foreshocks associated with this sequence.The MS6.0 Luxian earthquake in Sichuan Province,southwest China has caused serious damage with a relatively low magnitude,partly because the focal depth of the mainshock is relatively shallow (3.5 km).It is another strong earthquake occurring within the southeast Sichuan basin with low historical seismicity yet has increased significantly since 2015,probably due to shale gas development and associated hydraulic fracturing.