中南美洲地区地震序列的特征

共搜集到１９６０￣１９９０年中、南美洲地区１０个地震序列。其中１个是板内地震序列。这个板内地震序列表现出的特征是：震中分布区域的长轴较短，长短轴之比低；余震震源机制和主震震源机制相比变化大。其余９个是俯冲带上的板缘地震序列，它们的共同特征是：震中分布区域的长轴较长；震源深度下限超过地壳，可以达到７０ｋｍ以下（第１０号序列例外）；主震的震源机制受俯站带的走向、倾向和倾角的控制。但是这些震序列又分为两

FEATURE OF THE EARTHQUAKE SEQUENCES OF CENTRAL-SOUTH AMERICA

The location data of 10 earthquakes sequences of central-south America for the period 1960-1990 are collected. One of them is intraplate earthquake sequence and showed the feature :the major axis of the epicenter area is shorter,the ration of the major axis to minor axis is small. The other 9 sequences are interplate earthquake sequences occurred in the subduction zone and showed the common feature:the major axis of the epicenter area is longer,the depth of focus is 70km at most and is in the medium below crust(with the exception of the sequence No. 10),the fault plane solution of main shock in each scquence is controlled by the strike and dip of subduction zone. These sequences can be divided into two groups:group 1 includes 5 sequences of which the direction of major axis of the epicenter area is parallel to the strike of the subduction zone;group 2 includes 4sequences of which the direction of major axis of the epicenter area is perpendicular to the strikes of the subduction zone. For each sequence of group 1,ratio of the major axis of the epicenter area to the minor axis is larger;fault plane solutions of all aftershocks but a few early ones are not significantly different from that of the main shock. For group 2,ratio of the major axis of the epicenter area to the minor axis of some sequences is less;fault plane solutions of later aftershocks of a few sequences are significantly different from that of the main shock.