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

Abstract

Arc volcanism and intermediate-depth earthquakes are prolific at subduction zones and appear linked in some way. Alkaline and calc-alkaline magmas, typical of arc volcanism, show geochemical signatures which imply an influence of fluids derived from the subducting plate (Stern, 2002), and the metamorphic devolatilization that releases those fluids has been implicated in intermediate-depth earthquakes generation (Hacker et al., 2003). Although in many places arc volcanoes directly overlie prolific intermediate-depth earthquakes regions (e.g., Syracuse & Abers, 2006), some exceptions have been used to infer more exotic causes of calc-alkaline volcanism. One such region is the Wrangell volcanic field (WVF) in southcentral

Mapping the Lithosphere and Asthenosphere Beneath Alaska With Sp Converted Waves

“…The slab contours in profile C are from Daly et al. (2021). White circles at the top mark distance along the profile as shown in Figure 3.…”

Subduction of an Oceanic Plateau Across Southcentral Alaska: Scattered‐Wave Imaging

“…Slab-depth contours beneath Denali segment (Section 2) at 25-km intervals (thin black lines) after Ratchkovski and Hansen (2002). Slab-depth contours beneath Wrangell segment at 25-km intervals from this RF migration analysis and Daly et al (2021). Black and white stars are the forearc and backarc stations, respectively, used for Figure 3 Ferris et al, 2003) and Multidisciplinary Observations of Onshore Subduction (MOOS; Li et al, 2013), along with Transportable Array (TA; Ruppert & West, 2020), the Alaska Earthquake Center Network, and other local network stations.…”

“…Low‐frequency earthquakes and tremor suggest that the plate interface extends east to ∼146°W (Wech, 2016). Dense WBZ seismicity ends abruptly around 146°W, although a distinct sparse WBZ has been observed beneath the Wrangell segment (Stephens et al., 1984; Page et al., 1989; Daly et al., 2021). Some tomographic studies of the region show a faint high‐velocity anomaly at mantle depths in the Wrangell segment that has been interpreted as subducting material as far east as 140°W (e.g., Feng and Ritzwoller., 2019; Gou et al., 2019; Jiang et al., 2018), but other studies see no such anomaly (e.g., Eberhart‐Phillips et al., 2006; Martin‐Short et al., 2018, 2016; Nayak et al., 2020).…”

“…Slab-depth contours beneath Denali segment (Section 2) at 25-km intervals (thin black lines) afterRatchkovski and Hansen (2002). Slab-depth contours beneath Wrangell segment at 25-km intervals from this RF migration analysis andDaly et al (2021). Black and white stars are the forearc and backarc stations, respectively, used for Figure3.…”

Investigating the Effect of Mantle Flow and Viscosity Structure on Surface Velocities in Alaska Using 3‐D Geodynamic Models

“…A more recent study by Daly et al. (2021) utilized an improved seismometer array to detect earthquakes that indicate there is a subducted slab beneath the Wrangell volcanic field. Furthermore, the seismic receiver function results from Mann et al., 2022 indicate there may be a slab tear located between the down going Yakutat slab and the slab beneath the Wrangell volcanic field.…”