1983年菏泽5.9级地震

1983年11月7日山东省菏泽县发生5.9级地震。其地震类型基本属孤立型。这次地震有下列特点:无直接前震,余震次数很少且能量衰减快;余震震源位置集中且早期余震有成组成对出现现象;等烈度线畸变,内圈等烈度线有北东和北西两个长轴方向。本文还对这次地震的性质,破裂方式等进行了初步讨论。

THE 1983 HEZE EARTHQUAKE OF MAGNITUDE 5.9

An earthquake of magnitude 5.9, of a singleshock category occurred on November 7, 1983 in Heze county, Shandong province. Some interesting seismic features about the earthquake are found: no foreshoeks, very few aftershocks with strong attenuation of seismic energy; the epicenters of aftershocks clustered and the early aftershocks oeurred in pairs or groups; the isoseismal lines of intensity are distorted and the inner isoseis-mals are butterfly-shaped with two axes striking NE and WNW respectively, etc. In the present study, the nature and the fracture model of the main shock are discussed preliminarily.