西南太平洋地区地震序列的特征

FEATURES OF THE EARTHQUAKE SEQUENCES OF SOUTHWESTERN PACIFIC

共搜集到 1984～ 1990年西南太平洋地区 12个板缘地震序列。多数地震序列的特征是 :震中分布区域的长轴较长并且随主震震级和序列中强震次数而增加 ;震中分布区域的长、短轴长度的比值较高 ;地震序列的余震震源机制和主震的差异不大 ;震源深度下限超过地壳 ,可达 70km以上。走滑型主震占的比例低 ,高倾角滑动面的走向既有与俯冲带走向平行的也有横切的 ,个别逆冲型地震的断层面走向横切俯冲带。

Collected 12 examples of plate boundary earthquake sequences of Southwestern Pacific from 1984 to 1990. The features of most of the sequences are as below: the major axis of the epicenter area is longer,and increased with magnitude of the mainshock and mount of strong aftershocks,the ratio of the major axis to minor axis is larger; focal mechanism solutions of aftershocks are not significantly different to the solution of mainshock in a sequence; the deepest focus below the crust bottom can be at 70km or more.Percentage of strike-slip type mainshock is low. Some fault plane strikes of dip-slip type are parallel to the trend of subduction zone,and some are perpendicular to it.Fault planes strikes of a few reverse-slip type are perpendicular to the trend of subduction zone.They showed that different phenomena from fundamental feature of earthquake sequences in the plate subduction zone.