@article{HeimannVasyuraBathkeSudhausetal.2019,
  author    = {Heimann, Sebastian and Vasyura-Bathke, Hannes and Sudhaus, Henriette and Isken, Marius Paul and Kriegerowski, Marius and Steinberg, Andreas and Dahm, Torsten},
  title     = {A Python framework for efficient use of pre-computed Green's functions in seismological and other physical forward and inverse source problems},
  series = {Solid earth},
  volume    = {10},
  journal   = {Solid earth},
  number    = {6},
  publisher = {Copernicus},
  address   = {G{\"o}ttingen},
  issn      = {1869-9510},
  doi       = {10.5194/se-10-1921-2019},
  pages     = {1921 -- 1935},
  year      = {2019},
  abstract  = {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.},
  language  = {en}
}
@article{DahmHeimannMetzetal.2021,
  author    = {Dahm, Torsten and Heimann, Sebastian and Metz, Malte and Isken, Marius Paul},
  title     = {A self-similar dynamic rupture model based on the simplified wave-rupture analogy},
  series = {Geophysical journal international / the Royal Astronomical Society, the Deutsche Geophysikalische Gesellschaft and the European Geophysical Society},
  volume    = {225},
  journal   = {Geophysical journal international / the Royal Astronomical Society, the Deutsche Geophysikalische Gesellschaft and the European Geophysical Society},
  number    = {3},
  publisher = {Oxford Univ. Press},
  address   = {Oxford},
  issn      = {0956-540X},
  doi       = {10.1093/gji/ggab045},
  pages     = {1586 -- 1604},
  year      = {2021},
  abstract  = {The investigation of stresses, faults, structure and seismic hazards requires a good understanding and mapping of earthquake rupture and slip. Constraining the finite source of earthquakes from seismic and geodetic waveforms is challenging because the directional effects of the rupture itself are small and dynamic numerical solutions often include a large number of free parameters. The computational effort is large and therefore difficult to use in an exploratory forward modelling or inversion approach. Here, we use a simplified self-similar fracture model with only a few parameters, where the propagation of the fracture front is decoupled from the calculation of the slip. The approximative method is flexible and computationally efficient. We discuss the strengths and limitations of the model with real-case examples of well-studied earthquakes. These include the M-w 8.3 2015 Illapel, Chile, megathrust earthquake at the plate interface of a subduction zone and examples of continental intraplate strike-slip earthquakes like the M-w 7.1 2016 Kumamoto, Japan, multisegment variable slip event or the M-w 7.5 2018 Palu, Indonesia, supershear earthquake. Despite the simplicity of the model, a large number of observational features ranging from different rupture-front isochrones and slip distributions to directional waveform effects or high slip patches are easy to model. The temporal evolution of slip rate and rise time are derived from the incremental growth of the rupture and the stress drop without imposing other constraints. The new model is fast and implemented in the open-source Python seismology toolbox Pyrocko, ready to study the physics of rupture and to be used in finite source inversions.},
  language  = {en}
}
@article{JamalreyhaniRezapourCescaetal.2022,
  author    = {Jamalreyhani, Mohammadreza and Rezapour, Mehdi and Cesca, Simone and Dahm, Torsten and Heimann, Sebastian and Sudhaus, Henriette and Isken, Marius Paul},
  title     = {Insight into the 2017-2019 Lurestan arc seismic sequence (Zagros, Iran); complex earthquake interaction in the basement and sediments},
  series = {Geophysical journal international},
  volume    = {230},
  journal   = {Geophysical journal international},
  number    = {1},
  publisher = {Oxford Univ. Press},
  address   = {Oxford},
  issn      = {0956-540X},
  doi       = {10.1093/gji/ggac057},
  pages     = {114 -- 130},
  year      = {2022},
  abstract  = {Despite its high-seismogenic potential, the details of the seismogenic processes of Zagros Simply Folded Belt (SFB) remains debated. Three large earthquakes (M-w 7.3, 5.9 and 6.3) struck in the Lurestan arc of the Zagros SFB in 2017 and 2018. The sequence was recorded by seismic stations at regional, and teleseismic distances. Coseismic surface displacements, measured by Sentinel-1A/B satellites, provide additional data and a unique opportunity to study these earthquakes in detail. Here, we complement previous studies of the coseismic slip distribution of the 12 November 2017 M-w 7.3 Ezgeleh earthquake by a detailed analysis of its aftershocks, and we analysed the rupture process of the two interrelated earthquakes (25 August 2018 M-w 5.9 Tazehabad and the 25 November 2018 M-w 6.3 Sarpol-e Zahab earthquakes). We model the surface displacements obtained from Interferometric Synthetic Aperture Radar (InSAR) measurements and seismic records. We conduct non-linear probabilistic optimizations based on joint InSAR and seismic data to obtain finite-fault rupture of these earthquakes. The Lurestan arc earthquakes were followed by a sustained aftershock activity, with 133 aftershocks exceeding M-n 4.0 until 30 December 2019. We rely on the permanent seismic networks of Iran and Iraq to relocate similar to 700 M-n 3 + events and estimate moment tensor solutions for 85 aftershocks down to M-w 4.0. The 2017 Ezgeleh earthquake has been considered to activate a low-angle (similar to 17 degrees) dextral-thrust fault at the depth of 10-20 km. However, most of its aftershocks have shallow centroid depths (8-12 km). The joint interpretation of finite source models, moment tensor and hypocentral location indicate that the 2018 Tazehabad and Sarpol-e Zahab earthquakes ruptured different strike-slip structures, providing evidence for the activation of the sinistral and dextral strike-slip faults, respectively. The deformation in the Lurestan arc is seismically accommodated by a complex fault system involving both thrust and strike-slip faults. Knowledge about the deformation characteristics is important for the understanding of crustal shortening, faulting and hazard and risk assessment in this region.},
  language  = {en}
}
@article{IskenVasyuraBathkeDahmetal.2022,
  author    = {Isken, Marius Paul and Vasyura-Bathke, Hannes and Dahm, Torsten and Heimann, Sebastian},
  title     = {De-noising distributed acoustic sensing data using an adaptive frequency-wavenumber filter},
  series = {Geophysical journal international},
  volume    = {231},
  journal   = {Geophysical journal international},
  number    = {2},
  publisher = {Oxford University Press},
  address   = {Oxford},
  issn      = {0956-540X},
  doi       = {10.1093/gji/ggac229},
  pages     = {944 -- 949},
  year      = {2022},
  abstract  = {Data recorded by distributed acoustic sensing (DAS) along an optical fibre sample the spatial and temporal properties of seismic wavefields at high spatial density. Often leading to massive amount of data when collected for seismic monitoring along many kilometre long cables. The spatially coherent signals from weak seismic arrivals within the data are often obscured by incoherent noise. We present a flexible and computationally efficient filtering technique, which makes use of the dense spatial and temporal sampling of the data and that can handle the large amount of data. The presented adaptive frequency-wavenumber filter suppresses the incoherent seismic noise while amplifying the coherent wavefield. We analyse the response of the filter in time and spectral domain, and we demonstrate its performance on a noisy data set that was recorded in a vertical borehole observatory showing active and passive seismic phase arrivals. Lastly, we present a performant open-source software implementation enabling real-time filtering of large DAS data sets.},
  language  = {en}
}
@article{PilzIskenFlemingetal.2021,
  author    = {Pilz, Marco and Isken, Marius Paul and Fleming, Kevin and Orunbaev, Sagynbek and Moldobekov, Bolot},
  title     = {Long- and short-term monitoring of a dam in response to seasonal changes and ground motion loading},
  series = {Pure and applied geophysics : PAGEOPH ; continuation of Geofisica pura e applicata},
  volume    = {178},
  journal   = {Pure and applied geophysics : PAGEOPH ; continuation of Geofisica pura e applicata},
  number    = {10},
  publisher = {Birkh{\"a}user},
  address   = {Basel},
  issn      = {0033-4553},
  doi       = {10.1007/s00024-021-02861-5},
  pages     = {4001 -- 4020},
  year      = {2021},
  abstract  = {An experimental multi-parameter structural monitoring system has been installed on the Kurpsai dam, western Kyrgyz Republic. This system consists of equipment for seismic and strain measurements for making longer- (days, weeks, months) and shorter- (minutes, hours) term observations, dealing with, for example seasonal (longer) effects or the response of the dam to ground motion from noise or seismic events. Fibre-optic strain sensors allow the seasonal and daily opening and closing of the spaces between the dam's segments to be tracked. For the seismic data, both amplitude (in terms of using differences in amplitudes in the Fourier spectra for mapping the modes of vibration of the dam) and their time-frequency distribution for a set of small to moderate seismic events are investigated and the corresponding phase variabilities (in terms of lagged coherency) are evaluated. Even for moderate levels of seismic-induced ground motion, some influence on the structural response can be detected, which then sees the dam quickly return to its original state. A seasonal component was identified in the strain measurements, while levels of noise arising from the operation of the dam's generators and associated water flow have been provisionally identified.},
  language  = {en}
}
@article{FlovenzWangHersiretal.2022,
  author    = {Fl{\´o}venz, {\´O}lafur G. and Wang, Rongjiang and Hersir, Gylfi P{\´a}ll and Dahm, Torsten and Hainzl, Sebastian and Vassileva, Magdalena and Drouin, Vincent and Heimann, Sebastian and Isken, Marius Paul and Gudnason, Egill {\´A}. and {\´A}g{\´u}stsson, Kristj{\´a}n and {\´A}g{\´u}stsd{\´o}ttir, Thorbj{\"o}rg and Hor{\´a}lek, Josef and Motagh, Mahdi and Walter, Thomas R. and Rivalta, Eleonora and Jousset, Philippe and Krawczyk, Charlotte M. and Milkereit, Claus},
  title     = {Cyclical geothermal unrest as a precursor to Iceland's 2021 Fagradalsfjall eruption},
  series = {Nature geoscience},
  volume    = {15},
  journal   = {Nature geoscience},
  number    = {5},
  publisher = {Nature Research},
  address   = {Berlin},
  issn      = {1752-0894},
  doi       = {10.1038/s41561-022-00930-5},
  pages     = {397 -- 404},
  year      = {2022},
  abstract  = {Understanding and constraining the source of geodetic deformation in volcanic areas is an important component of hazard assessment. Here, we analyse deformation and seismicity for one year before the March 2021 Fagradalsfjall eruption in Iceland. We generate a high-resolution catalogue of 39,500 earthquakes using optical cable recordings and develop a poroelastic model to describe three pre-eruptional uplift and subsidence cycles at the Svartsengi geothermal field, 8 km west of the eruption site. We find the observed deformation is best explained by cyclic intrusions into a permeable aquifer by a fluid injected at 4 km depth below the geothermal field, with a total volume of 0.11 ± 0.05 km3 and a density of 850 ± 350 kg m-3. We therefore suggest that ingression of magmatic CO2 can explain the geodetic, gravity and seismic data, although some contribution of magma cannot be excluded.},
  language  = {en}
}