关键词: 地震中期预测, 地震低活动异常, 多参数检验, 中国大陆

Abstract: From the study of seismicity in Chinese mainland, we found that obvious low seismicity anomalies occur 1~2 years before some strong earthquakes. Using M≥5.0 seismic data in recent 100 years, in this paper the relations between low seismicity anomaly and future seismicity of Chinese mainland were analyzed. We established low seismicity indicator from annual frequency of M≥5.0 earthquakes, the maximum earthquake magnitude, and M≥6.0 seismic quiescence. Furthermore, the relations between low seismicity anomaly and future strong earthquakes were checked through probabilistic gain index β, predicting efficiency ratio α and R value for earthquake forecasting efficiency testing. Preliminary results indicate that some coefficients exist between low seismicity anomaly and future seismicity in Chinese mainland, mainly reflected in M≥7.8 huge earthquakes. However, the coefficients of M≥7.8 huge earthquakes are limited, and probabilistic gain index β and predicting efficiency ratio α are about 3, R value for earthquake forecasting efficiency testing is about 0.2. For M＜7.5 earthquakes, low seismicity anomaly is not exhibited, its probabilistic gain index β and predicting efficiency ratio α are near 0, which appear as random relations. The turning point at which some relations with low seismicity anomaly show is M7.5.

Key words: Seismicity in Chinese mainland, Low seismicity anomaly, Multi-parameter test, Mid-term forecasting