Seismic imaging and petrology explain highly explosive eruptions of Merapi Volcano, Indonesia

S Widiyantoro,M Ramdhan,A D Nugraha,J.-P Métaxian,A A Fahmi,C Martel,S Erdmann,P R Cummins,A Laurin,A Budi-Santoso

doi:10.1038/s41598-018-31293-w

Abstract

Our seismic tomographic images characterize, for the first time, spatial and volumetric details of the subvertical magma plumbing system of Merapi Volcano. We present P- and S-wave arrival time data, which were collected in a dense seismic network, known as DOMERAPI, installed around the volcano for 18 months. The P- and S-wave arrival time data with similar path coverage reveal a high Vp/Vs structure extending from a depth of ≥20 km below mean sea level (MSL) up to the summit of the volcano. Combined with results of petrological studies, our seismic tomography data allow us to propose: (1) the existence of a shallow zone of intense fluid percolation, directly below the summit of the volcano; (2) a main, pre-eruptive magma reservoir at ≥ 10 to 20 km below MSL that is orders of magnitude larger than erupted magma volumes; (3) a deep magma reservoir at MOHO depth which supplies the main reservoir; and (4) an extensive, subvertical fluid-magma-transfer zone from the mantle to the surface. Such high-resolution spatial constraints on the volcano plumbing system as shown are an important advance in our ability to forecast and to mitigate the hazard potential of Merapi’s future eruptions.

Highlights

The distinctive character of the seismicity, gas emissions, and lava petrology of the 2010 eruption all suggest that the difference with respect to previous post-19th century eruptions was the unusually rapid ascent of a large volume of volatile-rich magma sourced from depths >8 km[4,5,6,7]
A large number of petrological studies have already proposed models for Merapi’s magma plumbing system, ranging from those that suggest the presence of many small magma reservoirs throughout the crust[8,9,10,11] to those that favor storage in one or more main zones[5,6,12]
It is possible to interpret the mid-crustal part of this anomaly as a magma reservoir consisting of a solid matrix with pockets of partial melt[19], but such a complicated reservoir involving considerable lateral transport begs the question of how large volumes of volatile-rich magma can be rapidly delivered to the surface to sustain the type of explosive eruption that occurred in 2010

Summary

Introduction

A large number of petrological studies have already proposed models for Merapi’s magma plumbing system, ranging from those that suggest the presence of many small magma reservoirs throughout the crust[8,9,10,11] to those that favor storage in one or more main zones[5,6,12]. Previous geophysical studies have either focused on the shallow system below Merapi at depths of

Results

Conclusion