2022/06/18 by Carl Tape, Anthony Lomax · 1 citation
Earth and Planetary Sciences · #earthquake and tectonic studies #Geological and Geochemical Analysis #High-pressure geophysics and materials #Aftershock #Geology #Seismology #Trench #Subduction #Plate tectonics #Bay #Tectonics #Oceanography
paper · doi:10.1029/2022jb024336
openalex publication_date 2022/06/18 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/31
Abstract With five earthquakes (1938, 1946, 1957, 1964, and 1965), the Aleutian‐Alaska subduction plate boundary ruptured a length of 3,548 km. We revisit these five earthquakes—first studied in detail by Sykes (1971, https://doi.org/10.1029/JB076i032p08021 )—through probabilistic relocation of carefully selected mainshocks and aftershocks. Our final catalog of 324 events is established from a set of 12 mainshocks that includes all M w ≥ 7.7 megathrust earthquakes. Using the relocated catalog, we create revised aftershock regions delimited both parallel and normal to the trench. These aftershock regions exhibit significant differences from previous studies, with the following basic findings: the 10 November 1938 M w 8.3 earthquake extended further west, to the Shumagin Islands, and further east, into the Kodiak region, relative to the prevailing aftershock region established by McCann et al. (1979, https://doi.org/10.1007/978-3-0348-6430-52 ). The 01 April 1946 M w 8.6 sequence was anomalously concentrated near the trench, which implies near‐trench coseismic slip that contributed to the exceptionally large tsunami. The 09 March 1957 M w 8.6 aftershocks spanned a 1,230 km length with numerous aftershocks within the outer‐rise region of the incoming Pacific plate. The 28 March 1964 M w 9.2 aftershocks extended east into the Pamplona thrust system (south of Icy Bay, Alaska), suggesting coseismic rupture into this region; this is consistent with coseismic static displacements, as well as current estimates of interseismic locking. The post‐1965 events we examine are all smaller than the earlier events, but since they occurred in an era of improved data collection (seismic, geodetic, and tsunami), they provide a better opportunity for assessing the link between the distribution of aftershocks and the occurrence of coseismic, postseismic, and interseismic slip.