@misc{Paetzel2023,
  type      = {Master Thesis},
  author    = {P{\"a}tzel, Jonas},
  title     = {Seismic site characterization using broadband and DAS ambient vibration measurements on Mt Etna, Italy},
  doi       = {10.25932/publishup-61379},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-613793},
  school      = {Universit{\"a}t Potsdam},
  pages     = {95},
  year      = {2023},
  abstract  = {Both horizontal-to-vertical (H/V) spectral ratios and the spatial autocorrelation method (SPAC) have proven to be valuable tools to gain insight into local site effects by ambient noise measurements. Here, the two methods are employed to assess the subsurface velocity structure at the Piano delle Concazze area on Mt Etna. Volcanic tremor records from an array of 26 broadband seismometers is processed and a strong variability of H/V ratios during periods of increased volcanic activity is found. From the spatial distribution of H/V peak frequencies, a geologic structure in the north-east of Piano delle Concazze is imaged which is interpreted as the Ellittico caldera rim. The method is extended to include both velocity data from the broadband stations and distributed acoustic sensing data from a co-located 1.5 km long fibre optic cable. High maximum amplitude values of the resulting ratios along the trajectory of the cable coincide with known faults. The outcome also indicates previously unmapped parts of a fault. The geologic interpretation is in good agreement with inversion results from magnetic survey data. Using the neighborhood algorithm, spatial autocorrelation curves obtained from the modified SPAC are inverted alone and jointly with the H/V peak frequencies for 1D shear wave velocity profiles. The obtained models are largely consistent with published models and were able to validate the results from the fibre optic cable.},
  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}
}