Seismicity properties of the Chain Transform Fault inferred using data from the PI-LAB experiment
Seismicity properties of the Chain Transform Fault inferred using data from the PI-LAB experiment
复制标题
使用 PI-LAB 实验数据推断的链变换断层的地震活动特性
DOI：
10.1002/essoar.10511418.1
复制
发表时间：
2022
期刊：
影响因子：
--
通讯作者：
Leptokaropoulos K
中科院分区：
文献类型：
--
作者：
Leptokaropoulos K
海洋转换断层很有趣，因为它们不会产生鉴于其规模而预期的那么大的地震。我们使用海底地震仪 (OBS) 阵列记录的一年当地地震活动和地球物理数据来研究位于赤道大西洋中部的链变换的地震构造特性。我们通过考虑全球目录中的较强地震（MW ≥ 5.0）来及时扩展我们的分析。基于多维OBS地震活动聚类分析，我们将Chain分为东、中、西三个区域。 OBS记录的地震活动最高的是Chain东部地区，该地区有菱形地形高点，rMBA重力异常为负，历史上仅有少数MW≥5.5的事件。 OBS 西部和中部地区的地震活动率较低。然而，根据 OBS 和历史数据推断，这些区域容纳了大部分地震矩的释放。我们没有发现远程动态触发的证据，只有潮汐和静态应力触发的微弱证据。较高的 b 值与较低的 rMBA 以及较浅的水深显着相关，可能与增厚的地壳有关。我们的结果表明，沿链的横向异质性较高：具有中度至低OBS地震活动率、偶尔发生MW ≥ 6.0地震的斑块被具有丰富OBS活动但很少发生5.5 ≤ MW < 6.0地震的段所中断。这种分割可能是由于可变的流体循环和变化，这也可能随时间变化。
Oceanic transform faults are intriguing in that they do not produce earthquakes as large as might be expected given their dimensions. We use 1-year of local seismicity recorded on an array of ocean bottom seismometers (OBS) and geophysical data to study the seismotectonic properties of the Chain transform, located in the equatorial Mid-Atlantic. We extend our analysis back in time by considering stronger earthquakes (MW ≥ 5.0) from global catalogs. We divide Chain into three areas (eastern, central, and western) based on multi-dimensional OBS seismicity cluster analysis. Seismic activity recorded by the OBS is the highest at the eastern area of Chain where there is a lozenge shaped topographic high, a negative rMBA gravity anomaly, and only a few historical MW ≥ 5.5 events. OBS seismicity rates are lower in the western and central areas. However, these areas accommodate the majority of seismic moment release, as inferred from both OBS and historical data. We find no evidence of remote dynamic triggering and only weak evidence of tidal and static stress triggering. Higher b-values are significantly correlated with lower rMBA and also with shallower bathymetry, potentially related to thickened crust. Our results suggest high lateral heterogeneity along Chain: Patches with moderate to low OBS seismicity rates that occasionally host MW ≥ 6.0 earthquakes are interrupted by segments with abundant OBS activity but few historical events with 5.5 ≤ MW < 6.0. This segmentation is possibly due to variable fluid circulation and alteration, which may also be variable in time.