Mapping the Pacific Slab Edge and Toroidal Mantle Flow Beneath Kamchatka

Abstract

The Kamchatka subduction zone is located at the northwestern corner of the Pacific Ocean, where the Pacific plate, the Okhotsk plate, and the North American plate strongly interact with each other (Figure 1). The Pacific plate is subducting beneath the Okhotsk plate along the Kamchatka trench (Bird, 2003). Earthquakes take place actively down to a depth of ∼600 km on the south of ∼57°N latitude, whereas there is no deep seismicity on the north (Figure 1b). Volcanoes on Kamchatka can be divided into three trench-parallel volcanic chains (e.g., Tatsumi et al., 1994), which are located in the Sredinny Range, the Central Kamchatka Depression (CKD), and the Eastern Volcanic Front (EVF). The EVF is the active volcanic front, whereas the Sredinny Range generally represents the volcanic front in the Pliocene (Iveson et al., 2021;Volynets et al., 2010). The CKD is an active intra-arc rift zone where very active volcanoes of the Klyuchevskoy Group and Shiveluch exist (Koulakov et al., 2020).

P and S Wave Anisotropic Tomography of the Banda Subduction Zone

“…The complexity of the slab shape could lead to toroidal mantle flow around the slab edge, as suggested by numerical simulations (Husson et al., 2022). This kind of toroidal mantle flow around the slab edge has also been revealed in other subduction zones, such as Cascadia (Eakin et al., 2010; D. Zhao & Hua, 2021) and Kamchatka (Jiang et al., 2009; L. Zhao et al., 2021). Our 3‐D anisotropic tomography actually reveals the mantle flow pattern induced by the highly curved slab and slab‐slab interactions (Figure 4), providing new insight into mantle convection in subduction zones.…”

The 2013 Slab‐Wide Kamchatka Earthquake Sequence

“…The Kamchatka volcanic arc is one of the most active on earth with large melt volume production. Also, because of the proximity to the northern termination of the subduction, the toroidal mantle flow around the edge of the plate (Levin et al., 2005; Yogodzinski et al., 2001; Peyton et al., 2001; I. Koulakov et al., 2020; Zhao et al., 2021) might modify melting conditions of the oceanic plate and have an influence on the subduction dynamics.…”

Peeking inside the mantle structure beneath the Italian region through SKS shear wave splitting anisotropy: a review

“…Tears or break-ups in the slab usually produce some circular anisotropy pattern around the edges due to toroidal mantle flow [e.g. Civello and Margheriti 2004;Faccenna et al, 2005;Faccenda and Capitanio, 2013;Confal et al, 2018;Zhao et al, 2021] and can twist trench-parallel flow [Pondrelli et al, 2022].…”

“…"Frozen-in" anisotropy in the actively subducting plate [Zhao et al, 2021] or in remnant slab fragments can leave an imprint on the shear wave splitting measurements.…”