【摘要】 分析了1976年松潘7.2级地震和2008年汶川8.0级地震前异常现象。汶川8.0级地震为地震活跃期的首发大地震,震前区域性中小地震相对平静,区域地震活动b值为0.77;松潘7.2级地震是活跃期间发生的地震,震中附近地区地震活动密集,曾发生松潘黄龙6.5级地震,震前区域地震活动b值为0.62;汶川地震前区域主压应力方位与错动类型总体上与8.0级地震给出的解大体一致,这与松潘7.2级地震前的情况有显著差异,震前地震与余震震型有差异。根据观测数据的分析和异常判定结果认为,松潘地震与汶川地震前的观测异常没有一个台项是重复出现的,短临异常数前者显著多于后者。松潘地震与汶川地震前的宏观异常现象差异极大,更未出现火球、地光临震异常现象。这说明,已有的短临前兆观测异常的出现仅有个案特征,而无普适意义。更多还原

【Abstract】 The anomalous items reported before both the 1976 Songpan M7.2 Earthquake and the 2008 Wenchuan M8.0 Earthquake are analyzed.The 2008 Wenchuan M8.0 Earthquake is a first fore-earthquake.The seismicity level around the seismic source area before the 1976 Songpan M7.2 Earthquake is low.The b-value of the Songpan regional seismicity is 0.77.This event occurred in the seismic activity period and the seismic cluster occurred around the source area of the 1976 Songpan M7.2 Earthquake.The fore event is the Songpan-Huanglong M6.5 Earthquake and the b-value of regional seismicity is 0.62.The principle stress trend of this region and the slip type before the 2008 Wenchuan M8.0 Earthquake were almost as same as that calculated by the 2008 Wenchuan M8.0 Earthquake.This is different notably from that before the 1976 Songpan M7.2 Earthquake.The fore-earthquake and the after-earthquake pattern before the 1976 Songpan M7.2 Earthquake the earthquake were different from that of the 2008 Wenchuan M8.0 Earthquake.Our analysis on the observation data and the anomalous macro reports show that no anomalous items appeared again and the number of short and impend anomalous items appeared before the 1976 Songpan M7.2 Earthquake is bigger than that of the 2008 Wenchuan M8.0 Earthquake.The differences between two earthquakes are big.No fireball and ground light appeared.All these comparison and contracts show that there are many differences among different seismic events and no solid evidences for each seismic event exist.更多还原