@article{FischerHrubcovaDahmetal.2022, author = {Fischer, Tom{\´a}š and Hrubcova, Pavla and Dahm, Torsten and Woith, Heiko and Vylita, Tom{\´a}š and Ohrnberger, Matthias and Vlček, Josef and Horalek, Josef and Dedecek, Petr and Zimmer, Martin and Lipus, Martin P. and Pierdominici, Simona and Kallmeyer, Jens and Kr{\"u}ger, Frank and Hannemann, Katrin and Korn, Michael and Kaempf, Horst and Reinsch, Thomas and Klicpera, Jakub and Vollmer, Daniel and Daskalopoulou, Kyriaki}, title = {ICDP drilling of the Eger Rift observatory}, series = {Scientific drilling : reports on deep earth sampling and monitoring}, volume = {31}, journal = {Scientific drilling : reports on deep earth sampling and monitoring}, publisher = {Copernicus}, address = {G{\"o}ttingen}, issn = {1816-8957}, doi = {10.5194/sd-31-31-2022}, pages = {31 -- 49}, year = {2022}, abstract = {The new in situ geodynamic laboratory established in the framework of the ICDP Eger project aims to develop the most modern, comprehensive, multiparameter laboratory at depth for studying earthquake swarms, crustal fluid flow, mantle-derived CO2 and helium degassing, and processes of the deep biosphere. In order to reach a new level of high-frequency, near-source and multiparameter observation of earthquake swarms and related phenomena, such a laboratory comprises a set of shallow boreholes with high-frequency 3-D seismic arrays as well as modern continuous real-time fluid monitoring at depth and the study of the deep biosphere. This laboratory is located in the western part of the Eger Rift at the border of the Czech Republic and Germany (in the West Bohemia-Vogtland geodynamic region) and comprises a set of five boreholes around the seismoactive zone. To date, all monitoring boreholes have been drilled. This includes the seismic monitoring boreholes S1, S2 and S3 in the crystalline units north and east of the major Nov{\´y} Kostel seismogenic zone, borehole F3 in the Hartoušov mofette field and borehole S4 in the newly discovered Bažina maar near Lib{\´a}. Supplementary borehole P1 is being prepared in the Neualbenreuth maar for paleoclimate and biological research. At each of these sites, a borehole broadband seismometer will be installed, and sites S1, S2 and S3 will also host a 3-D seismic array composed of a vertical geophone chain and surface seismic array. Seismic instrumenting has been completed in the S1 borehole and is in preparation in the remaining four monitoring boreholes. The continuous fluid monitoring site of Hartoušov includes three boreholes, F1, F2 and F3, and a pilot monitoring phase is underway. The laboratory also enables one to analyze microbial activity at CO2 mofettes and maar structures in the context of changes in habitats. The drillings into the maar volcanoes contribute to a better understanding of the Quaternary paleoclimate and volcanic activity.}, language = {en} } @article{FischerHrubcovaDahmetal.2022, author = {Fischer, Tomas and Hrubcova, Pavla and Dahm, Torsten and Woith, Heiko and Vylita, Tomas and Ohrnberger, Matthias and Vlcek, Josef and Horalek, Josef and Dedecek, Petr and Zimmer, Martin and Lipus, Martin P. and Pierdominici, Simona and Kallmeyer, Jens and Kr{\"u}ger, Frank and Hannemann, Katrin and Korn, Michael and K{\"a}mpf, Horst and Reinsch, Thomas and Klicpera, Jakub and Vollmer, Daniel and Daskalopoulou, Kyriaki}, title = {ICDP drilling of the Eger Rift observatory}, series = {Scientific Drilling}, volume = {31}, journal = {Scientific Drilling}, publisher = {Copernicus}, address = {G{\"o}ttingen}, issn = {1816-8957}, doi = {10.5194/sd-31-31-2022}, pages = {31 -- 49}, year = {2022}, abstract = {The new in situ geodynamic laboratory established in the framework of the ICDP Eger project aims to develop the most modern, comprehensive, multiparameter laboratory at depth for studying earthquake swarms, crustal fluid flow, mantle-derived CO2 and helium degassing, and processes of the deep biosphere. In order to reach a new level of high-frequency, near-source and multiparameter observation of earthquake swarms and related phenomena, such a laboratory comprises a set of shallow boreholes with high-frequency 3-D seismic arrays as well as modern continuous real-time fluid monitoring at depth and the study of the deep biosphere. This laboratory is located in the western part of the Eger Rift at the border of the Czech Republic and Germany (in the West Bohemia-Vogtland geodynamic region) and comprises a set of five boreholes around the seismoactive zone. To date, all monitoring boreholes have been drilled. This includes the seismic monitoring boreholes S1, S2 and S3 in the crystalline units north and east of the major Novy Kostel seismogenic zone, borehole F3 in the Hartousov mofette field and borehole S4 in the newly discovered Bazina maar near Liba. Supplementary borehole P1 is being prepared in the Neualbenreuth maar for paleoclimate and biological research. At each of these sites, a borehole broadband seismometer will be installed, and sites S1, S2 and S3 will also host a 3-D seismic array composed of a vertical geophone chain and surface seismic array. Seismic instrumenting has been completed in the S1 borehole and is in preparation in the remaining four monitoring boreholes. The continuous fluid monitoring site of Hartousov includes three boreholes, F1, F2 and F3, and a pilot monitoring phase is underway. The laboratory also enables one to analyze microbial activity at CO2 mofettes and maar structures in the context of changes in habitats. The drillings into the maar volcanoes contribute to a better understanding of the Quaternary paleoclimate and volcanic activity.}, language = {en} } @article{EiblRosskopfSciottoetal.2022, author = {Eibl, Eva P. S. and Rosskopf, Martina and Sciotto, Mariangela and Currenti, Gilda and Di Grazia, Giuseppe and Jousset, Philippe and Kr{\"u}ger, Frank and Weber, Michael}, title = {Performance of a rotational sensor to decipher volcano seismic signals on Etna, Italy}, series = {Journal of geophysical research : Solid earth}, volume = {127}, journal = {Journal of geophysical research : Solid earth}, number = {6}, publisher = {Wiley}, address = {Hoboken, NJ}, issn = {0148-0227}, doi = {10.1029/2021JB023617}, pages = {22}, year = {2022}, abstract = {Volcano-seismic signals such as long-period events and tremor are important indicators for volcanic activity and unrest. However, their wavefield is complex and characterization and location using traditional seismological instrumentation is often difficult. In 2019 we recorded the full seismic wavefield using a newly developed 3C rotational sensor co-located with a 3C traditional seismometer on Etna, Italy. We compare the performance of the rotational sensor, the seismometer and the Istituto Nazionale di Geofisica e Vulcanologia-Osservatorio Etneo (INGV-OE) seismic network with respect to the analysis of complex volcano-seismic signals. We create event catalogs for volcano-tectonic (VT) and long-period (LP) events combining a STA/LTA algorithm and cross-correlations. The event detection based on the rotational sensor is as reliable as the seismometer-based detection. The LP events are dominated by SH-type waves. Derived SH phase velocities range from 500 to 1,000 m/s for LP events and 300-400 m/s for volcanic tremor. SH-waves compose the tremor during weak volcanic activity and SH- and SV-waves during sustained strombolian activity. We derive back azimuths using (a) horizontal rotational components and (b) vertical rotation rate and transverse acceleration. The estimated back azimuths are consistent with the INGV-OE event location for (a) VT events with an epicentral distance larger than 3 km and some closer events, (b) LP events and tremor in the main crater area. Measuring the full wavefield we can reliably analyze the back azimuths, phase velocities and wavefield composition for VT, LP events and tremor in regions that are difficult to access such as volcanoes.}, language = {en} } @article{WeidleWiesenbergElSharkawyetal.2022, author = {Weidle, Christian and Wiesenberg, Lars and El-Sharkawy, Amr and Kr{\"u}ger, Frank and Scharf, Andreas and Agard, Philippe and Meier, Thomas}, title = {A 3-D crustal shear wave velocity model and Moho map below the Semail Ophiolite, eastern Arabia}, 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/ggac223}, pages = {817 -- 834}, year = {2022}, abstract = {The Semail Ophiolite in eastern Arabia is the largest and best-exposed slice of oceanic lithosphere on land. Detailed knowledge of the tectonic evolution of the shallow crust, in particular during and after ophiolite obduction in Late Cretaceous times is contrasted by few constraints on physical and compositional properties of the middle and lower continental crust below the obducted units. The role of inherited, pre-obduction crustal architecture remains therefore unaccounted for in our understanding of crustal evolution and the present-day geology. Based on seismological data acquired during a 27-month campaign in northern Oman, Ambient Seismic Noise Tomography and Receiver Function analysis provide for the first time a 3-D radially anisotropic shear wave velocity (V-S) model and a consistent Moho map below the iconic Semail Ophiolite. The model highlights deep crustal boundaries that segment the eastern Arabian basement in two distinct units. The previously undescribed Western Jabal Akhdar Zone separates Arabian crust with typical continental properties and a thickness of similar to 40-45 km in the northwest from a compositionally different terrane in the southeast that is interpreted as a terrane accreted during the Pan-African orogeny in Neoproterozoic times. East of the Ibra Zone, another deep crustal boundary, crustal thickness decreases to 30-35 km and very high lower crustal V-S suggest large-scale mafic intrusions into, and possible underplating of the Arabian continental crust that occurred most likely during Permian breakup of Pangea. Mafic reworking is sharply bounded by the (upper crustal) Semail Gap Fault Zone, northwest of which no such high velocities are found in the crust. Topography of the Oman Mountains is supported by a mild crustal root and Moho depth below the highest topography, the Jabal Akhdar Dome, is similar to 42 km. Radial anisotropy is robustly resolved in the upper crust and aids in discriminating dipping allochthonous units from autochthonous sedimentary rocks that are indistinguishable by isotropic V-S alone. Lateral thickness variations of the ophiolite highlight the Haylayn Ophiolite Massif on the northern flank of Jabal Akhdar Dome and the Hawasina Window as the deepest reaching unit. Ophiolite thickness is similar to 10 km in the southern and northern massifs, and <= 5 km elsewhere.}, language = {en} }