Local seismicity around the Chain Transform Fault at the Mid-Atlantic Ridge from OBS observations
Local seismicity around the Chain Transform Fault at the Mid-Atlantic Ridge from OBS observations
复制标题
来自 OBS 观测的大西洋中脊链式转换断层周围的局部地震活动
DOI：
--
复制
发表时间：
2023
影响因子：
2.8
通讯作者：
R. Abercrombie
中科院分区：
文献类型：
--
作者：
D. Schlaphorst;C. Rychert;Nicholas Harmon;S. Hicks;P. Bogiatzis;J. Kendall;R. Abercrombie
沿转换断层的地震活动为我们理解控制地震破裂的因素提供了重要的限制。与大陆断层相比，海洋转换断层的结构相对简单，因此其信息量特别大。局部网络已经对几个快速移动的转换断层的地震活动性进行了研究，但迄今为止，对慢速扩张的山脊中的转换断层的研究还很少。在这里，我们提出了第一个本地地震活动目录，该目录基于 2016 年 3 月至 2017 年 3 月期间由 39 个海底地震仪组成的临时宽带网络记录的事件数据，这些地震仪位于大西洋中脊 (MAR) 缓慢移动的链转换断层 (CTF) 周围。我们通过同时反演由事件 P 和 S 到达时间提供的一维速度模型，定位了该区域的 972 个事件。我们使用偏矩张量反演来细化较大事件的深度和震源机制。大多数地震位于CTF（700）、罗曼什转换断层（94）和MAR（155）沿线；在连续断裂带或板内位置可以观察到较小的数量（23）。山脊事件的特征是正断层，大多数转换事件的特征是走滑断层，但有几种可能与该地区压应力有关的反向机制。 CTF 事件的震级范围为 1.1 至 5.6，完整度约为 2.3。沿着 CTF，我们计算出 b 值为 0.81 ± 0.09。事件深度大多浅于海平面以下 15 公里 (523)，但少数高质量地震 (16) 位于更深的位置，其中一些 (8) 位于比简单热模型 600°C 等温线预测的脆性转变更深的位置。更深的事件可以通过海水渗透对脆性破坏极限的控制来解释。
Seismicity along transform faults provides important constraints for our understanding of the factors that control earthquake ruptures. Oceanic transform faults are particularly informative due to their relatively simple structure in comparison to their continental counterparts. The seismicity of several fast-moving transform faults has been investigated by local networks, but as of today there been few studies of transform faults in slow spreading ridges. Here we present the first local seismicity catalogue based on event data recorded by a temporary broadband network of 39 ocean bottom seismometers located around the slow-moving Chain Transform Fault (CTF) along the Mid-Atlantic Ridge (MAR) from March 2016 to March 2017. We locate 972 events in the area by simultaneously inverting for a 1-D velocity model informed by the event P- and S-arrival times. We refine the depths and focal mechanisms of the larger events using deviatoric moment tensor inversion. Most of the earthquakes are located along the CTF (700) and Romanche transform fault (94) and the MAR (155); a smaller number (23) can be observed on the continuing fracture zones or in intraplate locations. The ridge events are characterised by normal faulting and most of the transform events are characterised by strike slip faulting, but with several reverse mechanisms that are likely related to transpressional stresses in the region. CTF events range in magnitude from 1.1 to 5.6 with a magnitude of completeness around 2.3. Along the CTF we calculate a b-value of 0.81 ± 0.09. The event depths are mostly shallower than 15 km below sea level (523), but a small number of high-quality earthquakes (16) are located deeper, with some (8) located deeper than the brittle-ductile transition as predicted by the 600˚C-isotherm from a simple thermal model. The deeper events could be explained by the control of seawater infiltration on the brittle failure limit.
影响因子：
18.3
作者：
Kuna, Vaclav M.;Nabelek, John L.;Braunmiller, Jochen
通讯作者：
Braunmiller, Jochen
影响因子：
18.3
作者：
Hicks, Stephen P.;Okuwaki, Ryo;Sudhaus, Henriette
通讯作者：
Sudhaus, Henriette