Seismic activities and earthquake potential in the Tibetan Plateau

The Tibetan Plateau is a region with intensive tectonic deformation and high level earthquake activity. On the basis of historical records, there have been 18 earthquakes with magnitude over 8 and more than 100 events with magnitude between 7 and 7. 9 in the plateau. All of these events occured either along plate boundary of the Himalaya or along boundaries among the intra-plate fault blocks as well as sub-blocks. There have been three phases of earthquake clustering in the Tibetan Plateau, 1920 to 1937, 1947 to 1976, and 1995 to present, since instrumental seismic records began in 1900. Each phase of the cluster is characterized by events of magnitude over 8 and a number of events of magnitude over 7 to form an earthquake series. The three phases are the Haiyuan-Gulang earthquake series in 1920s to 1930s, the Chayu-Dangxiong earthquake series in 1950s to 1970s, and the Kunlun-Wenchuan series since the beginning of this century. Each earthquake series also has its major active region of occurrences. For example, the major active region of occurrence is associated with the newest phase of earthquake series is the Bayan Har fault block. The episodes of seismic activity in the Tibetan Plateau coincide with the high level activities of global mega-earthquake (M-w >= 8) activity. The Kunlun-Wenchuan earthquake series concurs with the global earthquake activity since 2001 suggesting geodynamic connections between them. Based on careful comparative studies, we suggest the current phase of earthquake activity continues today giving that the global mega-earthquakes (M(w)8 similar to 9) occur frequently along plate boundaries and major intra-plate earthquakes (M(w)7 similar to 8) occur along boundaries of crustal fault block. Through studies of relationships between global and regional earthquake activities and of temporal and spatial distribution of the earthquakes in the Tibetan Plateau, this paper summarized general tendencies of current earthquake activity, assesses recent earthquake potential, and proposes suggestions for intensive earthquake monitoring.