On the mechanism of interaction between strong earthquakes and volcanism in subduction zones

Abstract

The relationship between strong earthquakes and powerful volcanism in subduction zones are discussed. It is shown that abnormally strong earthquakes or a group of strong earthquakes and powerful volcanic events or volcanic activation of large areas can be considered as an interconnected geodynamic pair. At high level of horizontal compression, magma-conducting faults are clamped and volcanism in the upper part of the crust is hindered. Mega-earthquakes or a series of strong earthquakes reduce the level of horizontal compression in the crust of the island arc (continent active margin), which creates favorable conditions for the resumption of volcanic activity. For major faults located along the strike of subduction zones, upward movement of magma during volcanic eruptions or intracrustal magmatism leads to an increase in horizontal compression stresses in the surrounding rocks to the pressure level of rising magma. As a result, a horizontal compression stress state is restored in the crust and, thus, the cycle is closed. Once again, a state emerges in which earthquakes are an effective mechanism for reducing stresses.

Keywords

• stresses
• volcanism
• earthquakes
• compression
• tension, faults
• magma