Is uplift of volcano clusters in the Tohoku Volcanic Arc, Japan, driven by magma accumulation in hot zones? A geodynamic modeling study

Abstract

In many volcanic arcs, the rate of tectonic uplift cannot be explained by lithospheric plate motion alone but may be associated with dynamic uplift. Buoyant forces associated with underplated magma bodies lift the upper crust and leads to relatively high rates of topographic change. One such region is northern Honshu, Japan, where Quaternary volcano clusters are spatially associated with uplifted crust and isostatic gravity anomalies. Axisymmetric inversion of Bouguer gravity data for the Sengan volcano cluster shows that these gravity anomalies can be modeled by 30 km radius bodies emplaced at ∼15 km depth. Axisymmetric, finite element models, generated using GTECTON, of a layered Earth representative of the Tohoku crust indicate that the deformation of these midcrustal intrusions produces elevated topography on the surface directly above the intrusion that is bounded by a shallow peripheral trough. The wavelengths of vertical deformation produced by these bodies are sensitive to the thickness of the models' elastic layer and relatively insensitive to the models' rheology. This suggests that the amplitude of the vertical deformation represents a trade‐off between the size of the intrusion and the thickness of the elastic layer and is less strongly influenced by the rheology of the lithosphere into which the bodies are emplaced. Our results are consistent with hot zone and hot finger models for the arc and indicate that Tohoku Volcanic Arc features such as gravity anomalies and uplifted basement are related to crustal magma intrusions and hot zones rather than directly related to mantle processes.

Large‐Volume and Shallow Magma Intrusions in the Blackfoot Reservoir Volcanic Field (Idaho, USA)

“…Their model of the gravity anomalies in the CDF is consistent with the spatial association of the anomalies with young silicic domes. Also, this interpretation is consistent with prominent gravity anomalies associated with shallow intrusions elsewhere (Battaglia et al, 2003;Blakely, 1994;Bott & Smithson, 1967;Finn & Williams, 1982;George et al, 2016;Miller et al, 2017;Paulatto et al, 2019). We provide newly collected ground-based and boat-based gravity data that further constrain these anomalies and their relationship to Quaternary volcanoes and faults.…”

Nuisance Flooding and Relative Sea-Level Rise: the Importance of Present-Day Land Motion

“…The load P is approximated with a disc of height d : where ρ w = 1000 kg m −3 is the water density and g = 9.8 m s −2 is the gravitational acceleration. Our solution is based on numerical evaluation of equation ( 1 ) using the Finite Element Modeling (FEM) code GTecton 59 in the axisymmetric version 60 . The response of the fluid substratum at the base of the plate (the term ρ s gw ) is assumed to be Winkler type in equation ( 1 ), thus the isostatic adjustment is estimated through the use of Winkler restoring forces 61 .…”

A Geophysical Model for the Origin of Volcano Vent Clusters in a Colorado Plateau Volcanic Field

“…Structures such as folds (e.g., Wetmore et al, 2009) and faults (e.g., van den Hove et al, 2017) may alter magma ascent pathways. Density discontinuities or rigidity contrasts in one part of the crust may tend to enhance sill formation and arrest dike ascent (e.g., George et al, 2016;Kavanagh et al, 2006) also a mechanism invoked to explain SVF volcanism (Putirka & Condit, 2003).…”