| 预位移终止相与突跳型前兆类型 |
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| 引用本文： | 秦保燕,汪进,刘光远.预位移终止相与突跳型前兆类型[J].西北地震学报,1988,10(1):1-11. |
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| 作者姓名： | 秦保燕 汪进 刘光远 |
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| 作者单位： | 国家地震局兰州地震研究所
(秦保燕，汪进)，国家地震局兰州地震研究所(刘光远) |
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| 摘 要： | 本文从理论上讨论了两种预位移终止相。一种是预位移在震源断层面上局部地区发生,简称为局域预位移;另一种是预位移在整个断层面上展开,称为全域预位移。这两种预位移的终止条件有重大差异,这种差异导致预位移终止相的差异,从而使预位移引起的长周期波,以及由长周期波产生的突跳型前兆也产生差异。得到的初步研究结果如下: 1.大多数大地震发生前的预位移属局域预位移,而中强震大多属全域预位移。2.局域预位移的震源过程为有限源传播,全域预位移为有限源与瞬时面源。前者仅有一个长周期P波,后者产生两个不同到时的长周期P波。3.局域预位移和全域预位移所引起的长周期波与它们各自的源时间函数相近。前者产生单峰型突跳前兆,后者产生双峰型突跳前兆。由这两种前兆异常类型可粗略判断未来地震的强度。4.由于大震局域预位移区的尺度与中强地震全域预位移区尺度相当,因而它们的预位移幅度相近,从而大震和中强震前大多数前兆异常幅度相近。这样从理论上解释了前兆异常幅度与震级无关这一观测事实。
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PRE-DISPLACEMENT STOPPING PHASE AND SUDDEN TYPES OF PRECURSOR |
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| Qin Baoyan,Wang Jin and Liu Guangyuan.PRE-DISPLACEMENT STOPPING PHASE AND SUDDEN TYPES OF PRECURSOR[J].Northwestern Seismological Journal,1988,10(1):1-11. |
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| Authors: | Qin Baoyan Wang Jin and Liu Guangyuan |
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| Institution: | Seismological Institute of Lanzhou, State Seismological Bureau,Seismological Institute of Lanzhou, State Seismological Bureau and Seismological Institute of Lanzhou, State Seismological Bureau |
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| Abstract: | This paper theoretically discussed two kinds of pre-displacement stopping phases. One occurs in part area of fault, we call it partial area predisplacement. Another occurs in the whole fault, we call it whole area pre-displacement. There are obvious differences of stopping conditions between the two kinds of pre-displacements, which result in difference of pre-displcement stopping phases and difference of long-period wave as well as difference of sudden types of precursors induced by long-period wave. The preliminary results are as follows:(1) The pre-displacement before the most of large earthquakes is partial area pre-displacement, but that before the most of moderate earthquakes whole area pre-displacement.(2) The source process of partial area pre-displacement is finite moving source and that of whole area pre-displacement is combination of finite moving source and instantaneous source. The former only produce one long-period P-wave, but the latter produced two long-period P-waves with different arriving time.(3) The long-period P-wave induced by partial area or whole area predisplace-ments is similar to their source time function. The former produced single peak type of precursor, the latter produced double peak type of precursor. So the magnitude of future earthquake can be judged approximately by type of precursors.(4) Because extent of partial area pre-displacement region before large earthquake is approximate to extent of whole pre-displacement region before moderate earthquake, their pre-placement amplitudes is also approximate. Such results can explain the fact that the amplitudes of precursor is not related to magnitude of earthquake. |
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