The transition along the strike of the Sunda subduction zone, from oceanic subduction in the west to subduction of continental Australian lithosphere in the east is envisioned as one of the canonical examples of the structural changes that take place within an overriding plate when a continental lithosphere wedge enters a subduction zone. 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. The 28 March 1964 Mw 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 09 March 1957 Mw 8.6 aftershocks spanned a 1,230 km length with numerous aftershocks within the outer‐rise region of the incoming Pacific plate. The 01 April 1946 Mw 8.6 sequence was anomalously concentrated near the trench, which implies near‐trench coseismic slip that contributed to the exceptionally large tsunami. These aftershock regions exhibit significant differences from previous studies, with the following basic findings: the 10 November 1938 Mw 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. Using the relocated catalog, we create revised aftershock regions delimited both parallel and normal to the trench. Our final catalog of 324 events is established from a set of 12 mainshocks that includes all Mw ≥ 7.7 megathrust earthquakes. We revisit these five earthquakes-first studied in detail by Sykes (1971, )-through probabilistic relocation of carefully selected mainshocks and aftershocks. With five earthquakes (1938, 1946, 1957, 1964, and 1965), the Aleutian‐Alaska subduction plate boundary ruptured a length of 3,548 km. Our method of assessing the degree of seismic coupling differs from that of Ruff and Kanamori, who used the moment' magnitude (Mw) of either the largest event or the cumulative moment magnitude (Mw') along a subduction zone during the period 1900 to 1980 as measures of seismic coupling.We also compute the cumulative moment magnitude (Mw') defined by Ruff and Kanamori as the moment magnitude (Mw) obtained from the total seismic moment released in one sequence of events and normalized to a subduction zone 1000 km long. and the rate and age parameters by discussing below differences between our study and those of Ruff and Kanamori.Table 3 To compare our results (Figure 12) with previous studies, we plot seismic coupling in the rate-age diagram of Ruff and Kanamori We clarify the lack of correlation between is so even when our calculated downdip width is narrower than most previous estimates, and even if we assume that the percentage of transverse motion (Table 3) is released as fully coupled strike-slip events that occur within the overriding plate.
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