TY  - JOUR
A1  - Heimann, Sebastian
A1  - Vasyura-Bathke, Hannes
A1  - Sudhaus, Henriette
A1  - Isken, Marius Paul
A1  - Kriegerowski, Marius
A1  - Steinberg, Andreas
A1  - Dahm, Torsten
T1  - A Python framework for efficient use of pre-computed Green's functions in seismological and other physical forward and inverse source problems
JF  - Solid earth
N2  - The computation of such synthetic GFs is computationally and operationally demanding. As a consequence, the onthe-fly recalculation of synthetic GFs in each iteration of an optimisation is time-consuming and impractical. Therefore, the pre-calculation and efficient storage of synthetic GFs on a dense grid of source to receiver combinations enables the efficient lookup and utilisation of GFs in time-critical scenarios. We present a Python-based framework and toolkit - Pyrocko-GF - that enables the pre-calculation of synthetic GF stores, which are independent of their numerical calculation method and GF transfer function. The framework aids in the creation of such GF stores by interfacing a suite of established numerical forward modelling codes in seismology (computational back ends). So far, interfaces to back ends for layered Earth model cases have been provided; however, the architecture of Pyrocko-GF is designed to cover back ends for other geometries (e.g. full 3-D heterogeneous media) and other physical quantities (e.g. gravity, pressure, tilt). Therefore, Pyrocko-GF defines an extensible GF storage format suitable for a wide range of GF types, especially handling elasticity and wave propagation problems. The framework assists with visualisations, quality control, and the exchange of GF stores, which is supported through an online platform that provides many pre-calculated GF stores for local, regional, and global studies. The Pyrocko-GF toolkit comes with a well-documented application programming interface (API) for the Python programming language to efficiently facilitate forward modelling of geophysical processes, e.g. synthetic waveforms or static displacements for a wide range of source models.
Y1  - 2019
U6  - https://doi.org/10.5194/se-10-1921-2019
SN  - 1869-9510
SN  - 1869-9529
VL  - 10
IS  - 6
SP  - 1921
EP  - 1935
PB  - Copernicus
CY  - Göttingen
ER  - 
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  -