Characteristics and Predictive Significance of Spatio-Temporal Space Images of <i>M</i> ≥ 4.0 Seismic Gaps on the Southeastern Margin of the Tibetan Plateau

Abstract

In the present study, seismic gaps were identified as periods with no occurrence of M ≥ 4.0 earthquake over dT ≥ 400 days. After examining all records in the Sichuan–Yunnan–Tibet–Qinghai junction area on the southeastern margin of the Tibetan Plateau in 1970–2022, a total of six M ≥ 4.0 seismic gaps were identified. Spatio-temporal images of the seismic gaps had similar characteristics and demonstrated spatial overlapping and statistical significance. The quiet periods of the six seismic gaps included 419–777 days (approximately 580 days on average). The semi-major-axis and semi-minor-axis lengths were in the 880–1050 km (approximately 987 km on average) and 500–570 km (about 533 km on average) ranges, respectively. Case analysis results revealed that the images of M ≥ 4.0 seismic gaps were of high significance in predicting M ≥ 6.7 strong earthquakes in the region, and they could be used as a predictive index on a time scale of about 1–0.5 years or less.

Keywords

• southeastern margin of the Tibetan Plateau
• <i>M</i> ≥ 4.0 seismic gap
• <i>M</i> ≥ 6.7 strong earthquake
• predictive index