【摘要】 根据Andrews谱积分方法,采用近震源Brune圆盘模型,研究了2003年6月3日青岛崂山ML4.1地震序列破裂过程中应力降变化情况。结果表明,崂山序列主震静应力降为24MPa,动态应力降大约为静态应力降的2.2倍;崂山序列余震应力降普遍低于5MPa,约有80%的余震应力降小于1MPa,显示出与主震断层面有关的余震低应力降现象,这说明主震的破裂与余震破裂过程之间存在明显的差别。这种现象与崂山序列的弱强度衰减一致,表明此次序列的余震属于低能量破裂过程。计算结果显示:①由Andrews谱积分方法得到的小震应力降与震级大小存在一定的相关性;②小应力降事件的静态应力降和动态应力降的比值普遍小于1,未发现明显的应力降之比与Brune应力降之间的关系。更多还原

【Abstract】 Based on the Andrews’s spectra integral method,the near-source Brune model is employed to determine the source parameters,especially stress drop,of the June 5,2003 Laoshan ML=4.1 earthquake sequence in this paper.The result shows that,the static stress drop of the main shock is 24 MPa,and the dynamic stress drop is approximately 2.2 times greater than the static stress drop.The stress drops which are yield by aftershocks are generally lower than 5 MPa,and there are about 80 percent aftershock’s stress drops smaller than 1 MPa,which can be treated as low-stress-drop events.These states imply that the low stress is relative to the fault plane,and the rupture process of the main shock is obviously different to that of aftershocks.The low stress phenomenon is consistent with the weakly attenuation of Laoshan sequence activity.It indicates that the aftershock sequence is a rupture procedure with low energy released.Additionally,the result also has shown that,first,stress drop derived from Andrews’s method has relation to magnitude;second,the ratios of static to dynamic stress drops of events with low stress drops are generally smaller than 1,and they are independent of Brune stress drops.更多还原