Seismicity parameters preceding moderate to major earthquakes
Seismicity parameters preceding moderate to major earthquakes
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中到大地震前的地震活动参数
DOI：
10.1029/jb086ib10p09325
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发表时间：
1981
影响因子：
--
通讯作者：
C. Baag
中科院分区：
文献类型：
--
作者：
D. V. Seggern;S. Alexander;C. Baag
两个大型阵列（LASA 和 NORSAR）公报中报告的地震事件与 1970-1977 年期间 NEIS 公报中的地震事件合并。使用较低的截止值 mb = 5.8，在此期间选择了 LASA 或 NORSAR P 范围内的 510 个“主冲击”；并调查了在此之前的各种地震活动趋势。根据主震明显较短的时间延迟来寻找明确的前震，结果表明前震发生的真实率低于 20%。已证明前震几乎完全与浅层（h 100 公里）有关。对于浅层事件（<100公里），该变量揭示了许多聚类和时空地震间隙的实例，在主震之前几乎没有行为一致性的趋势。对大约90个具有足够地震活动性的主震区进行了地震前兆有效性的统计检验。使用五变量向量（事件间隔时间、事件间隔距离、震级、到主震的震中距离以及相对于主震的深度差），对主震发生前 500 天的“前兆”时间窗口中的每个事件以及在此之前 500 天的“正常”时间窗口中的每个事件，检验两组之间向量均值相等的原假设。在 90% 的置信水平下，不到 30% 的主震区域被发现表现出前兆地震活动变化。
整篇文章的缩微胶片上都有附录。来自美国地球物理联盟的命令，2000 Florida Avenue, N.W., Washington, D.C. 20009。文件 J81-007； 1.00 美元。付款必须伴随订单。
Seismic events reported in the bulletins of the two large arrays, LASA and NORSAR, were merged with those from the NEIS bulletin for the period 1970–1977. Using a lower cutoff of mb = 5.8, 510 ‘main shocks’ within the P range of LASA or NORSAR were selected for this period; and various seismicity trends prior to them were investigated. A search for definite foreshocks, based on a significantly short time delay to the main shock, revealed that the true rate of foreshock occurrence was less than 20%. Foreshocks are almost exclusively associated with shallow (h 100 km) was demonstrated. For shallow events (<100 km) this variable reveals numerous instances of clustering and spatial-temporal seismic gaps, with little tendency toward a uniformity of behavior prior to main shocks. A statistical test of the validity of seismic precursors was performed for approximately 90 main shock regions which had sufficient seismicity. Using a five-variable vector (interevent time, interevent distance, magnitude, epicentral distance to main shock, and depth difference relative to main shock) for each event in a ‘precursory’ time window of 500 days before the main shock and for each event in a ‘normal’ time window of 500 days before that, the null hypothesis of equal vector means between the two groups was tested. At 90% confidence level, less than 30% of the main shock regions were thus found to exhibit precursory seismicity changes.
Appendices are available with entire article on microfiche. Order from American Geophysical Union, 2000 Florida Avenue, N.W., Washington, D.C. 20009. Document J81-007; $1.00. Payment must accompany order.