Dynamic Strains for Earthquake Source Characterization
Dynamic Strains for Earthquake Source Characterization
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DOI：
10.1785/0220160155
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发表时间：
2017-03-01
影响因子：
3.3
通讯作者：
Crowell, Brendan W.
中科院分区：
文献类型：
--
作者：
Barbour, Andrew J.;Crowell, Brendan W.
应变仪测量与地震相关的弹性动力学变形，其检测特性与传统仪器相辅相成，但它们通常用于研究活动断层沿着和俯冲带的缓慢瞬态变形。在这里，我们分析了与2004-2014年146次地方和区域地震相关的板块边界观测站（PBO）钻孔应变仪（BSM）的动态应变，震级从M4.5到7.2。我们发现，地震应变的峰值可以预测从一般的回归距离和震级，提高精度，通过考虑与站点-站点效应和源路径效应相关的偏差，后者表现出最强的回归系数的影响。为了从总体上解释这些偏差的影响，我们纳入了来自CRUST1.0全球速度模型的地壳类型分类，这表明来自PBO BSM网络的高频应变数据携带了有关地壳结构和断层力学的信息：例如，在布兰科断裂带上的近海地震，产生的动态应变始终低于内华达州微板块和索尔顿海槽周围的地震。最后，我们测试我们的动态应变预测方程的2011年M9东北冲地震，特别是来自三角测量的137个高速率全球导航卫星系统地球观测网络站在日本的连续应变记录。当全球定位系统子网不受空间混叠的影响时，从这些数据和应变模型推断的力矩大小是一致的。
Strainmeters measure elastodynamic deformation associated with earthquakes over a broad frequency band, with detection characteristics that complement traditional instrumentation, but they are commonly used to study slow transient deformation along active faults and at subduction zones, for example. Here, we analyze dynamic strains at Plate Boundary Observatory (PBO) bore-hole strainmeters (BSM) associated with 146 local and regional earthquakes from 2004-2014, with magnitudes from M 4.5 to 7.2. We find that peak values in seismic strain can be predicted from a general regression against distance and magnitude, with improvements in accuracy gained by accounting for biases associated with site-station effects and source-path effects, the latter exhibiting the strongest influence on the regression coefficients. To account for the influence of these biases in a general way, we include crustal-type classifications from the CRUST1.0 global velocity model, which demonstrates that high-frequency strain data from the PBO BSM network carry information on crustal structure and fault mechanics: earthquakes nucleating offshore on the Blanco fracture zone, for example, generate consistently lower dynamic strains than earthquakes around the Sierra Nevada microplate and in the Salton trough. Finally, we test our dynamic strain prediction equations on the 2011M 9 Tohoku-Oki earthquake, specifically continuous strain records derived from triangulation of 137 high-rate Global Navigation Satellite System Earth Observation Network stations in Japan. Moment magnitudes inferred from these data and the strain model are in agreement when Global Positioning System subnetworks are unaffected by spatial aliasing.