Limited Shallow Slip for the 2020 Simeonof Earthquake, Alaska, Constrained by GNSS‐Acoustic
Limited Shallow Slip for the 2020 Simeonof Earthquake, Alaska, Constrained by GNSS‐Acoustic
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DOI：
10.1029/2023gl105045
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发表时间：
2023-08
影响因子：
5.2
通讯作者：
J. DeSanto;S. Webb;S. Nooner;D. Schmidt;B. Crowell;B. Brooks;T. Ericksen;C. Chadwell
中科院分区：
文献类型：
--
作者：
J. DeSanto;S. Webb;S. Nooner;D. Schmidt;B. Crowell;B. Brooks;T. Ericksen;C. Chadwell
2020年7月22日发生的Mw7.8 Simeonof地震是一次深层大型逆冲事件，沿阿拉斯加-阿留申俯冲带的舒玛金段破裂。这次地震发生在距离海底GNSS -声学站点IVB1约250公里的地方，在那里我们观测到地震前的速度为3.78±1.15 cm/年，与此同时，同震偏移向东0.6±0.7 cm，向北- 15.5±0.8 cm。我们利用IVB1与区域连续GNSS和强震台站的静态偏移量计算了同震破裂的滑动模型。该地点的小静态水平偏移排除了比以前从地面观测推断的更浅的破裂，证实了Simeonof地震是一次深逆冲地震。观测到的现场速度表明地震前部分锁定，这意味着显著的浅层应变积累，这样小的同震偏移量不太可能减轻上次同震破裂以来的所有累积应变。
The 22 July 2020 Mw7.8 Simeonof earthquake was a deep megathrust event that ruptured along the Shumagin segment of the Alaska‐Aleutian subduction zone. This earthquake occurred ∼250 km from a seafloor geodetic GNSS‐Acoustic site IVB1, where we observed a velocity of 3.78 ± 1.15 cm/yr with the down‐going slab prior to the earthquake followed by 0.6 ± 0.7 eastward and −15.5 ± 0.8 cm northward coseismic offset. We computed a slip model of the coseismic rupture using the static offset at IVB1 alongside regional continuous GNSS and strong motion stations. The small static horizontal offset at the site precludes significantly shallower rupture than previously inferred from terrestrial observations, confirming that the Simeonof earthquake was a deep megathrust earthquake. The observed site velocity implies partial locking prior to the earthquake, implying significant shallow strain accumulation such that the small coseismic offset is unlikely to have relieved all of the accumulated strain since the last coseismic rupture.