Understanding Volcano Activity Using 2D Simulation Models of MT Data

Abstract

2D resistivity models of magnetotelluric data had been simulated for studying magma activity within volcanic conduits. The simulated models can be used to understand the pre-eruption of volcanic behavior based on the change of resistivity responses measured on an active volcano. Four resistivity models of conduit states have been modeled using REBOCC MT forward modeling code. The models include a conduit with empty magma, the magma starts to accumulate in the conduit, the magma rises, and the conduit full of magma. The resistivity value of the empty conduit and the magma material was 10 Ohm-m and 50.000 Ohm-m, respectively. While the conduit is located within a volcano composed of three resistivity layers, i.e., 100 Ohm-m, 400 Ohm-m, and 1000 Ohm-m from the top to the bottom. The synthetic data responses generated by each model were used to analyze each state. The calculated transfer function of magnetotelluric data includes apparent resistivity and phase for TE-mode. Each data set were calculated in range of period 0.001, 0.01, 0.1, 10, 100, 1000 s. The results showed that apparent resistivity responses increase with increasing the magma height in the conduit. The simulated models can be used to predict the height of the magma before it would be reached the surface as a precursor of a volcanic eruption.