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GPS-based slip models of one Mw 7.2 and twenty moderate earthquakes along the Sumatran plate boundary
Geoscience Letters ( IF 4 ) Pub Date : 2019-08-23 , DOI: 10.1186/s40562-019-0138-y
Nathanael Z. Wong , Lujia Feng , Emma M. Hill

Earthquake-induced deformation along the Sumatran plate boundary has been monitored by the Sumatran GPS Array (SuGAr) since 2002. This continuous GPS network recorded the coseismic deformation of 10 earthquakes with moment magnitude (Mw) larger than 7 and 20 with Mw in the range of 5.9–7 from 2002 to 2013. Among all these recorded events, one large Mw 7.2 event and most of the moderate ones (5.9 ≤ Mw < 7) have yet to be modeled with available GPS data. This is partially due to the limited number (≤ 4) of stations that recorded each event. In this paper, we explore the possibility of using the limited observations to derive sensible slip models for these “forgotten” Sumatran events. We model each event as a single rectangular patch of uniform slip and constrain most of the patch parameters using external information based on slab geometry and global teleseismic catalogs. For each event, we use a grid-search approach to find the preferred location of slip patches, which we present along with contours of error-weighted variance explained to indicate the uncertainties. We compare the center locations of our final slip patches with the centroid locations from the global Centroid Moment Tensor (gCMT) catalog and the epicenter locations from four other global catalogs. Our results show that the gCMT centroid locations for the 21 Sumatran earthquakes are systematically biased toward the southwest relative to the centers of our slip patches, while the epicenter locations from the four other catalogs are all consistently shifted toward the northeast. Although the available data have no resolving power for other source parameters, we find that simple forward modeling based on sparse but reliable near-field GPS data generally provides less biased and more accurate locations than global teleseismic catalogs along the Sumatran plate boundary. The catalog of slip models we present will have particular utility in the event of other significant earthquakes being generated by the same or proximal areas of the Sunda megathrust.

中文翻译:

一个基于GPS滑车型中号W¯¯沿苏门答腊板块边界7.2和二十强地震

自2002年以来,苏门答腊GPS阵列(SuGAr)一直监测着沿苏门答腊板块边界的地震引起的形变。这个连续的GPS网络记录了10级地震的同震形变,其矩震级(Mw)大于7,而20的Mw在该范围在2002年至2013年期间,这是5.9–7的事件。在所有这些记录的事件中,一个大型Mw 7.2事件和大多数中度事件(5.9≤Mw <7)尚未使用可用的GPS数据进行建模。部分原因是记录每个事件的电台数量有限(≤4)。在本文中,我们探索了使用有限的观测结果来为这些“被遗忘的”苏门答腊事件推导出明智的滑动模型的可能性。我们将每个事件建模为均匀滑动的单个矩形补丁,并使用基于平板几何和全球地震目录的外部信息来约束大多数补丁参数。对于每个事件,我们使用网格搜索方法找到滑点的首选位置,我们将其与误差加权方差的轮廓一起介绍,以说明不确定性。我们将最终滑片的中心位置与全球质心矩张量(gCMT)目录中的质心位置以及其他四个全球目录中的震中位置进行了比较。我们的结果表明,相对于我们滑动斑块的中心,苏门答腊岛21地震的gCMT重心位置系统地偏向西南方向,而其他四个目录的震中位置都一直向东北移动。尽管可用数据没有其他源参数的解析能力,但我们发现,基于稀疏但可靠的近场GPS数据进行的简单正向建模通常比沿苏门答腊板块边界的全球远震目录提供的偏斜少且定位准确。我们介绍的滑动模型目录在由Sun他大推力的相同或近端区域产生其他重大地震的情况下将具有特殊用途。我们发现,与沿苏门答腊板块边界的全球远震目录相比,基于稀疏但可靠的近场GPS数据的简单正向建模通常提供较少的偏差和更准确的位置。我们介绍的滑动模型目录在由Sun他大推力的相同或近端区域产生其他重大地震的情况下将具有特殊用途。我们发现,与沿苏门答腊板块边界的全球远震目录相比,基于稀疏但可靠的近场GPS数据的简单正向建模通常提供较少的偏差和更准确的位置。我们介绍的滑动模型目录在由Sun他大推力的相同或近端区域产生其他重大地震的情况下将具有特殊用途。
更新日期:2019-08-23
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