中小地震定量分析在地震区带划分中的应用——以龙门山地震带及邻区为例

Application of the Quantitative Analysis of Moderate-small Earthquakes for the Division of the Seismic Zones——Taking Longmenshan Seismic Belt and Its Adjacent Region as An Example

采用中小地震能量密度值计算方法,定量分析龙门山地震带及邻区1970年以来现代中小地震空间分布图像特征,探讨其与历史强震震中分布、主要断裂展布和地震带边界的关系,验证了新区划图中龙门山地震带边界修改方案的合理性。同时基于震级-频度分布原理,对所使用的中小地震资料进行完整性分析,分别给出了区域内不同时段的最小完整性震级MC。本研究为此地区地震区、带划分提供了定量依据,可供地震活动性分析和地震危险性评价研究时参考。

The energy density values of moderate-small earthquakes since 1970 in Longmenshan seismic belt and its adjacent region are calculated. The characteristics of distribution image of moderate-small earthquakes are analyzed quantitatively, and its relationship with the distribution of historical strong earthquakes and main fault zones, as well as with seismic belt boundaries are discussed. The result provides a quantitative base from moderate-small events to validity of the new division scheme of seismic zoning in Longmenshan area. In addition, the minimum completeness of magnitude Mc are given for each periods in the research area by completeness analysis for moderate-small earthquake data using the magnitude-frequency relation （Gutenberg-Richter relation）. The result provides a quantitative base for division of seismic belt in this region ,and can be a reference for seismicity analysis and earthquake risk evaluation.