1976年11月7日盐源—宁蒗6.7级地震的前兆异常特征

盐源—宁蒗６．７级地震具有较丰富的前兆异常。前兆异常具有长、中、短、临的阶段性；在时间分布上成批出现，在空间分布上集中在几个小范围内出现。趋势性异常分期分批，在几个小范围内出现。临震异常呈突发性的脉冲式突跳或大幅度的阶跃状的突变，出现的时间均在震前一个月，平均异常时间为１４天。震前半个月在震中区附近观测异常相对密集。

Precursor Characteristics of Nov. 7, 1976 Yangyuan-Ninglang Earthquake(Ms6.7)

There are a lot of earthquake precursors that show long-term, medium-term, short term characteristics before Nov.7, 1976 Yangyuang-Ninglang Earthquake (Ms6.7). Trendanomaly happens in groups one by one and in several small areas and also show sharp, pulsant and skip forms. All this anomalies happen one month before the earthquake. Theanomaly period is 14 days. These anomalies concentrate on the epicentral region half monthbefore the earthquake.