TY  - JOUR
A1  - Hensch, Martin
A1  - Dahm, Torsten
A1  - Ritter, Joachim
A1  - Heimann, Sebastian
A1  - Schmidt, Bernd
A1  - Stange, Stefan
A1  - Lehmann, Klaus
T1  - Deep low-frequency earthquakes reveal ongoing magmatic recharge beneath Laacher See Volcano (Eifel, Germany)
JF  - Geophysical journal international
N2  - The occurrence of deep low-frequency (DLF) microearthquakes beneath volcanoes is commonly attributed to mass transport in the volcanic plumbing system and used to infer feeding channels from and into magma reservoirs. The key question is how magmas migrate from depth to the shallow crust and whether magma reservoirs are currently being recharged. For the first time since the improvement of the local seismic networks in the East Eifel region (Rhineland-Palatinate, Germany), we detect and locate recurrent DLF earthquakes in the lower crust and upper mantle beneath the Laacher See Volcano (LSV), using a joint data set of permanent sensors and a temporary deployment. So far, eight DLF earthquake sequences were observed in four distinct clusters between 10 and 40 km depth. These clusters of weak events (M-L< 2) align along an approximately 80. southeast dipping line south of the LSV. Moment tensor solutions of these events have large shear components, and the irregular dispersion and long coda of body waves indicate interaction processes between shear cracks and fluids. We find a rotation of P-axes orientation for shallow tectonic earthquakes compared to DLF events, indicating that the stress field in the depth interval of DLF events might favour a vertical migration of magma or magmatic fluids. The caldera of the LSV was formed by the last major eruption of the East Eifel Volcanic Field only 12.9 kyr ago, fed by a shallow magma chamber at 5-8 km depth and erupting a total magma volume of 6.7 km(3). The observed DLF earthquake activity and continuous volcanic gas emissions around the LSV indicate an active magmatic system, possibly connected with an upper mantle melt zone.
KW  - Waveform inversion
KW  - Volcano seismology
KW  - Magma migration and fragmentation
KW  - Volcano monitoring
Y1  - 2019
U6  - https://doi.org/10.1093/gji/ggy532
SN  - 0956-540X
SN  - 1365-246X
VL  - 216
IS  - 3
SP  - 2025
EP  - 2036
PB  - Oxford Univ. Press
CY  - Oxford
ER  -