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强震来临之前预先发出警告的地震预警(EEW)系统是减轻地震灾害的关键。目前运行的地震预警系统基于的是点源假设,由于忽视有效源的效应导致震级幅度被低估,从而在大地震事件中效用受限。在这里,我们探讨地震预警使用活断层附近的小孔径地震台阵来实时表征破裂尺寸的概念。反向追踪台阵波形可实时估计出破裂前沿的范围(代表破裂的尺寸)和方向性,为现有的地震预警系统针对M>7地震提供附加的地震预警性能。我们在模拟的实时环境中对其实际运行,并分析由美国地质调查局帕克菲尔德密集地震台阵(UPSAR)监测的2004年加利福尼亚帕克菲尔德M6地震记录,以及由加利福尼亚圣迭戈强震传感器监测的2010年El Mayor-Cucapah M7.2地震记录。我们发现基于较小事件的数据校正由美国地质调查局帕克菲尔德密集地震台阵下方的倾斜结构引起的反方位角的偏差至关重要。我们估计的破裂长度比其他研究推断的长度短30%,但是对于地震预警的目标仍然是合理的。我们把这种差异归因于破裂方向性效应及单个台阵视野有限。这种方法的准确度也许会随视野重叠的台阵网而改善。我们对此通过九州和北海道北部两个Hi-net台网的台站群追踪2011年日本东北地震的破裂来予以说明。所得结果与远震反投影结果一致且得到了破裂长度及方向性的合理估计值。与提出的其他有限断层地震预警方法相比,该台阵方法受全球定位系统或地震台网的粗略性影响较小,提供了破裂的高频特征而对某些结构获得了比地震动更适合的预报因子。
Earthquake Early Warning (EEW) systems, which were pre-warned before the earthquake, are the key to mitigating the earthquake disaster. The earthquake early warning system currently in operation is based on the point source hypothesis that the magnitude of the magnitude is underestimated as a result of neglecting the effect of an effective source and thus has limited utility in the event of a major earthquake. Here, we explore the concept of real-time characterization of rupture size using a small-aperture seismic array near the active fault for earthquake warning. Backward tracking of array waveforms can estimate the range of fracture front (representing the size of fracture) and directivity in real time, providing additional seismic early warning performance for the existing earthquake early warning system for M> 7 earthquakes. We ran it in a simulated real-time environment and analyzed the 2004 Parker M6 seismic record in California, monitored by the United States Geological Survey Parks Richter Seismic Array (UPSAR), and the 2010, monitored by a strong earthquake sensor in San Diego, California El Mayor-Cucapah M7.2 Earthquake Record. We find it very important to correct the deviation of the azimuth angle caused by the inclined structure below the Parkinsonian Seismic Array of the United States Geological Survey based on the smaller event data. Our estimated rupture length is 30% shorter than other inferred lengths, but the goal of early warning of earthquakes is still reasonable. We attributed this difference to the ruptured directional effects and the limited field of view of a single mesa. The accuracy of this method may improve with the overlapping mesh network. We illustrate this through the station cluster of two Hi-net stations in Kyushu and northern Hokkaido that track the rupture of the 2011 northeast earthquake in Japan. The results are consistent with teleseismic backprojection results and reasonable estimates of rupture length and directivity are obtained. Compared with other proposed methods of early warning of finite faults, the array method is less affected by the coarse global positioning system or seismic network, provides the high-frequency characteristics of rupture and is more suitable for some structures than ground motion Of the predictors.