The 2002–2005 Changbaishan Volcanic Unrest Triggered by the 2002 M 7.2 Wangqing Deep Focus Earthquake

Guoming Liu,Zhigang Peng,Dongyang Liu,Chenyu Li,Yu Zhang,Maoliang Zhang,Yinan Liu,Bo Pan

doi:10.3389/feart.2020.599329

Abstract

One of the most active intraplate volcanoes in East Asia, Changbaishan volcano experienced unrest from July 2002 to July 2005. On 2002/06/28, the M 7.2 Wangqing deep-focus earthquake occurred ∼290 km northeast of Changbaishan volcano. While some studies have suggested a possible triggering relationship, the physical mechanism of such distant interaction is still not well understood. Using a template matching technique, which cross-correlates waveform of known events with continuous data, we perform systematic detection of microseismic events recorded by station CBS near Changbaishan volcano from July 1999 to July 2007. The detected earthquakes can be further categorized into three different types: volcano-tectonic (VT) events, long-period (LP) events and harmonic-spectra (HS) events. We detect 3763 VT events between July 2002 and July 2007. The intense VT earthquake swarm during the period from July 2002 to July 2005, along with recurring LPs and HSs and other geodetic/geochemical evidence, suggest magma movement during unrest. Compared with the hand-picked catalogue, the catalogue obtained by template matching technique reveals a delayed-triggering relationship between Wangqing deep-focus earthquake and unrest. The small magnitudes of the VT events and the limited numbers of LP and HS events suggest that the Wangqing mainshock likely triggered bubble excitation in the mid-crust magma system, resulting in overpressure and a small magma injection into the shallow magma chamber at a depth of ∼5 km, leading to the 3-years unrest.

Highlights

It is well known that large earthquakes are capable of triggering small to moderate-size earthquakes at long distances, especially in geothermal or volcanic regions (Hill and Prejean, 2015)
Seismic tomography (e.g., Zhao et al, 2009) has revealed that Changbaishan volcano is located above a big mantle wedge (BMW) defined by the subducting Pacific plate that is horizontally stagnant in the mantle transition zone (MTZ) and the overriding Eurasian plate
In order to provide a comprehensive view of the seismicity of Changbaishan volcano from 1999 to 2018, we use the joint earthquake catalogue, which include events produced by automatic detection from July 1999 to July 2007 and those listed in the Changbaishan Volcano Observatory (CHVO) catalogue after August 2007

Summary

Introduction

It is well known that large earthquakes are capable of triggering small to moderate-size earthquakes at long distances, especially in geothermal or volcanic regions (Hill and Prejean, 2015). Most remote earthquake-triggered eruptions occur along major plate boundaries and are associated with shallow subduction-zone earthquakes (e.g., Hill et al, 2002; Lara et al, 2004; Walter and Amelung, 2006, 2007; Sawi and Manga, 2018; Farías and Basualto, 2020). It is not clear whether deep-focus earthquakes are capable of triggering unrest and eruptions. Geodetic inversions of inflation during the 2002–2005 unrest revealed a possible shallow magma chamber at the depth range of ∼5 km (Xu et al, 2012)

Results

Discussion

Conclusion