On the Relationship between Mw and ML for Small Earthquakes
On the Relationship between Mw and ML for Small Earthquakes
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论小地震Mw与ML的关系
DOI：
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发表时间：
2016
期刊：
影响因子：
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通讯作者：
L. Chiaraluce
中科院分区：
文献类型：
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作者：
I. Munafo;L. Malagnini;L. Chiaraluce
摘要估算小震矩震级是一项具有挑战性的任务。测量其大小的一个可行的选择是计算其局部星等（ML）并将其转换为基于物理的MW。不幸的是，要正确地进行这样的转换并不容易;此外，即使许多研究表明，M L和M w之间的等效性对于小事件是不正确的，这两个参数有时被认为是严格等效的，无论地震的大小。使用随机振动理论，我们证明了在Mw ≤ 4以下，小地震的ML与其地震矩的对数成正比，并且以下关系成立：我们在台伯河上游（北方亚平宁山脉，意大利）的高质量数据集上测试了我们的发现，该数据集由范围为0≤ ML ≤ 3. 8的事件组成，我们计算了ML和Mw的精确估计。在线资料：处理过程的细节，经验区域衰减函数的图形，以及来自Alto Tiberina断层（ATF）数据集和地震目录的1191个事件的震源项。
Abstract Estimating the moment magnitudes ( M w ) of a small earthquake is a challenging task. One viable option to measure its size is to calculate its local magnitude ( M L ) and convert it to the physically based M w . Unfortunately, to correctly perform such a conversion is not easy; moreover, even though many studies demonstrate that the equivalence between M L and M w is incorrect for small events, these two parameters are sometimes thought to be strictly equivalent, regardless of the earthquake’s size. Using random vibration theory, we show that, below M w ∼4, the M L of a small earthquake is proportional to the logarithm of its seismic moment, and the following relationship holds: We test our findings on a high‐quality data set in the Upper Tiber Valley (northern Apennines, Italy), composed of events in the range of 0≤ M L ≤3.8, for which we compute accurate estimates of M L and M w . Online Material: Details of the processing procedure, figures of the empirical regional attenuation functional, and source terms of 1191 events from the Alto Tiberina fault (ATF) data set and earthquake catalog.