Coalescence microseismic mapping
Coalescence microseismic mapping
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DOI：
10.1093/gji/ggt331
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发表时间：
2013-12-01
影响因子：
2.8
通讯作者：
Tarasewicz, Jon
中科院分区：
文献类型：
--
作者：
Drew, Julian;White, Robert S.;Tarasewicz, Jon
地震通常是通过线性反演的离散到达时间拾取从地震台站网络记录的信号进行定位。如果选择错误，则会影响位置，从而导致潜在偏差。对于由密集地震台阵记录的数据，可改为应用直接成像方法。我们描述了“合并微震映射”的方法，这是两种方法之间的桥梁，将与地震数据连续记录在稀疏阵列。通过连续映射标量信号来自地震波的包络，我们得到强大的估计地震事件的起源的时空坐标。噪声数据从正确的源迁移，因此不会导致位置错误。该方法是植根于事件位置走时反演的贝叶斯公式，允许源位置的成像，并有能力处理建模走时中的错误。它具有与任何3-D速度模型一起工作的优点，因此可以包括各向异性。它还自动合并P波和S波数据。一个多分辨率网格搜索导致一个有效的实现，在一个更大的域搜索，包括联合反演的位置和速度结构可能的数据质量保证。我们讨论了这种方法的理论和实现，并说明它与真实的数据从微震事件在冰岛引起的地壳熔体侵入。
Earthquakes are commonly located by linearized inversion of discrete arrival time picks made from signals recorded at a network of seismic stations. If mis-picks are made, these will contribute to the location, therefore causing potential bias. For data recorded by a dense seismic array, direct imaging methods can be applied instead. We describe the 'coalescence microseismic mapping' method, which is a bridge between the two approaches and will operate with seismic data recorded continuously on a sparse array. By continuously mapping scalar signals derived from the envelope of seismic arrivals we derive robust estimates of the spatio-temporal coordinates of the origins of seismic events. Noisy data are migrated away from the correct origin, so do not contribute to errors in location. The method is rooted in a Bayesian formulation of event location traveltime inversion, allows imaging of source locations and has the capacity to handle errors in modelled traveltimes. It has the advantage of working with any 3-D velocity model, which therefore may include anisotropy. It also automatically incorporates both P- and S-wave data. A multiresolution grid search leads to an efficient implementation, with a search over a larger domain including joint inversion for location and velocity structure possible where warranted by the data quality. We discuss the theory and implementation of this method and illustrate it with real data from microseismic events in Iceland caused by melt intrusion in the crust.