1995年7月12日云南孟连中缅边界7.3级地震中、短、临预报及前兆异常特征
|
摘要
简述了孟连7.3级地震中、短、临3个阶段的预报情况及主要依据。重点讨论了异常时空分布特征。结果表明，震前1a震中附近地震学空间扫描出现小震额度、调制比等8项异常，为云南省异常项目最多的地区；震前235d内震中附近出现中强震的时空密集活跃。定点前兆中期异常的主要特征是，某些项目具有异常持续时间长、异常幅度大，如龙陵水氛异常持续时间长达4．5a；永胜短水准、短基线异常幅度分别达20．9mm和22mm短临阶段主要表现为某些项目如水温、水氧、地倾斜、地磁等出现“巨变异常”，异常幅度比正常变化大几倍至几十倍；水汞、水氛异常开始时间外围早、震中附近晚。空间上，中短期异常主要集中在距震中200～400km，临震异常主要集中在震中距200～300km，其异常台项百分比分别达26％～29％和36．8％，其它范围仅0～19％。云南中、短、临异常台站和台项百分比分别为54．5％和38．4％。
The medium-short term and impending prediction of\ Menglian M = 7.3 earthquakeare briefly described with their foundation, and the features of space-time distributionof precursory anomaly are mainly discussed as well. The results show that 8 items ofanomalies (the most of the province) appeared in seismological spatial scanning one yearbefore the main shock, for example, the abnormal frequency of small earthquakes andmodulation ratio, etc. are observed near the epicenter. Concentration of moderatelystrong earthquakes occurred near the epicenter 235 days before. The medium-termanomalies at the fixed point have the following features: some of the items appearedwith long lasting time and large anomaly amplitude. For instance, the anomaly of wat-er radon in Longling lasted for 4.5 years; the anomaly amplitudes for short baseline andshort levelling in Yongsheng reached 20.9 mm and22mm respectively; in the short-termand impending stages," greater changes" appeared in the items of water temperature,water radon, ground tilt, geomagnetism and so on. Their amplitudes are several ortens' times bigger than those of normal variations; Water mercury and water radonanomalies appeared earlier outside the epicenter, and later near it. The medium- andshort- term anomalies are spatially concentrated within the range of 200~ 400 km awayfrom the epicenter, and 200~300 km for the impending anomalies. The anomalous sta-tions and items reach 26%~ 29% and 36.8% resPectively, but only 0~19% in otherranges. Both re1ative numbers of anomalous stations and items for the medium-shortterm and impending anomalies in the whole province are about 54.5% and 38.4%.
The medium-short term and impending prediction of\ Menglian M = 7.3 earthquakeare briefly described with their foundation, and the features of space-time distributionof precursory anomaly are mainly discussed as well. The results show that 8 items ofanomalies (the most of the province) appeared in seismological spatial scanning one yearbefore the main shock, for example, the abnormal frequency of small earthquakes andmodulation ratio, etc. are observed near the epicenter. Concentration of moderatelystrong earthquakes occurred near the epicenter 235 days before. The medium-termanomalies at the fixed point have the following features: some of the items appearedwith long lasting time and large anomaly amplitude. For instance, the anomaly of wat-er radon in Longling lasted for 4.5 years; the anomaly amplitudes for short baseline andshort levelling in Yongsheng reached 20.9 mm and22mm respectively; in the short-termand impending stages," greater changes" appeared in the items of water temperature,water radon, ground tilt, geomagnetism and so on. Their amplitudes are several ortens' times bigger than those of normal variations; Water mercury and water radonanomalies appeared earlier outside the epicenter, and later near it. The medium- andshort- term anomalies are spatially concentrated within the range of 200~ 400 km awayfrom the epicenter, and 200~300 km for the impending anomalies. The anomalous sta-tions and items reach 26%~ 29% and 36.8% resPectively, but only 0~19% in otherranges. Both re1ative numbers of anomalous stations and items for the medium-shortterm and impending anomalies in the whole province are about 54.5% and 38.4%.
引文
1陈立德.云南地区6级以上地震前Ms≥4.7地震时空特征标度.高原地震,1993,5(3):13pp.
2梅世蓉.地震前兆场物理模式与前兆时空分布机制研究:(一)坚固体孕震模式的由来与证据.地震学报,1995,17(3):273～282
3陈立德,郭大庆,傅红,等.孕震系统宏观层次的单元体应力水平群体涨落模型.地震研究(英文稿),1996,19(4):415～423
2梅世蓉.地震前兆场物理模式与前兆时空分布机制研究:(一)坚固体孕震模式的由来与证据.地震学报,1995,17(3):273～282
3陈立德,郭大庆,傅红,等.孕震系统宏观层次的单元体应力水平群体涨落模型.地震研究(英文稿),1996,19(4):415～423
版权所有：© 2023 中国地质图书馆 中国地质调查局地学文献中心