Subduction of an Oceanic Plateau Across Southcentral Alaska: High?Resolution Seismicity

In southcentral Alaska, the Alaska-Aleutian Wadati-Benioff zone (WBZ) shows high seismicity rates west of 147°W. Further east, Wrangell volcanic field (WVF) has some world's largest continental volcanoes but there is equivocal evidence for a WBZ. We deployed dense seismometer array around WVF between 2016 and 2018 used data to increase number detected earthquakes using an autodetection location algorithm. One-dimensional velocity inversion double-difference earthquake further improve locations. Subcrustal form narrow band dipping seismicity—a weak clear WBZ—which strikes parallel trend dips highly oblique plate motion. The WBZ continuous from coast depth 100 km beneath Mount Wrangell. Earthquakes shallower than 40 are two WBZs, indicating continuity subducting Yakutat terrane across region. However, deeper offset by hundreds kilometers, which may indicate slab tear separating Alaska–Aleutian Seismicity differ over 2 orders magnitude separate despite similar incoming plate, with relatively seismically quiescent underlying much more prolific WVF. Higher slab-surface temperatures WVF, due flow edges geometry, lead low within crust, as seen in other warm slabs, abundant water still transported subarc depths mantle wedge.