地震研究

利用1973年1月1日至1988年11月5日云南区域地震台网记录的地震资料,获得了1988年澜沧—耿马地震前震源及附近区域多个地震活动性参数的空间分布图像,初步揭示了震前震源区应力状态。结果表明:澜沧—耿马地震之前,研究区地震活动性参数分布具有显著的空间不均匀性特征。澜沧7.6级地震震源区以低于0.7的异常低b值、低a值以及整个研究区最短的局部复发间隔T_L值为特征,表明震源所在断裂段在震前已处于高应力闭锁状态,具有发生大震的应力条件。

Using the seismic data recorded by the Yunnan Regional Seismic Network from Jan. 1,1973 to Nov. 5,1988,we obtained the spatial distribution of several seismicity parameters(including the a and b values in the frequency-magnitude relationship,and the local recurrence intervals T_L)in seismogenic and its surrounding area before Lancang-Gengma M7.6 and M7.2 earthquakes in 1988 to reveal the stress state in the seismogenic area before the earthquake. The main results show that the spatial distribution of seismic activity parameters was significantly heterogeneous in the study area before the Lancang-Gengma earthquake. The seismogenic area of the Lancang M7.6 earthquake had the characteristic of the abnormal low b-value that were much lower than the regional average(b<0.7),low a-value,and the shortest recurrence intervals T_L. All these implied that the fault where the focal located might have been locked under the high stress and more likely to generate major earthquakes.

引言
2 结果分析
3 讨论
4 结论

图1 澜沧—耿马地区主要断裂、1988年<br/>主震震源机制与3级以上余震震中及<br/>等震线分布图(张肇诚,1999)<br/>Fig.1 Distribution of main faults in Lancang-Gengma area,the focal mechanism of the 2 main-shocks,epicenters of ML≥3.0 aftershocks and the isoseismal map(Zhang,1999)

图1 澜沧—耿马地区主要断裂、1988年
主震震源机制与3级以上余震震中及
等震线分布图(张肇诚,1999)
Fig.1 Distribution of main faults in Lancang-Gengma area,the focal mechanism of the 2 main-shocks,epicenters of ML≥3.0 aftershocks and the isoseismal map(Zhang,1999)

图2 1973年1月1日至1988年11月5日澜沧—<br/>耿马地区ML≥1.0地震的震级—频度分布<br/>Fig.2 Frequency-magnitude distribution for ML≥1.0 earthquakes in Lancang-Gengma area from Jan.1,1973 to Nov.5,1988

图2 1973年1月1日至1988年11月5日澜沧—
耿马地区ML≥1.0地震的震级—频度分布
Fig.2 Frequency-magnitude distribution for ML≥1.0 earthquakes in Lancang-Gengma area from Jan.1,1973 to Nov.5,1988

图3 1973年1月1日至1988年11月5日澜沧—耿马地区ML≥2.5地震的震中分布<br/>Fig.3 Epicenter distribution of ML≥2.5 earthquakes in Lancang-Gengma area from Jan.1,1973 to Nov.5,1988

图3 1973年1月1日至1988年11月5日澜沧—耿马地区ML≥2.5地震的震中分布
Fig.3 Epicenter distribution of ML≥2.5 earthquakes in Lancang-Gengma area from Jan.1,1973 to Nov.5,1988

图4 澜沧—耿马地震前研究区域b值(a)和a值(b)空间分布<br/>Fig.4 Spatial distribution of b-value(a)and a-value(b)before the Lancang-Gengma earthquake in the study region

图4 澜沧—耿马地震前研究区域b值(a)和a值(b)空间分布
Fig.4 Spatial distribution of b-value(a)and a-value(b)before the Lancang-Gengma earthquake in the study region

图5 澜沧—耿马地震前研究区域TL值空间分布<br/>Fig.5 Spatial distribution of TL values before the Lancang-Gengma earthquake in the study region

图5 澜沧—耿马地震前研究区域TL值空间分布
Fig.5 Spatial distribution of TL values before the Lancang-Gengma earthquake in the study region

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备注

引言

2 结果分析

3 讨论

4 结论

期刊信息