@article{ZhuPilzCotton2020,
  author    = {Zhu, Chuanbin and Pilz, Marco and Cotton, Fabrice Pierre},
  title     = {Evaluation of a novel application of earthquake HVSR in site-specific amplification estimation},
  series = {Soil dynamics and earthquake engineering},
  volume    = {139},
  journal   = {Soil dynamics and earthquake engineering},
  publisher = {Elsevier},
  address   = {Oxford},
  issn      = {0267-7261},
  doi       = {10.1016/j.soildyn.2020.106301},
  pages     = {14},
  year      = {2020},
  abstract  = {Ground response analyses (GRA) model the vertical propagations of SH waves through flat-layered media (1DSH) and are widely carried out to evaluate local site effects in practice. Horizontal-to-vertical spectral ratio (HVSR) technique is a cost-effective approach to extract certain site-specific information, e.g., site fundamental frequency (f(0)), but HVSR values cannot be directly used to approximate the levels of S-wave amplifications. Motivated by the work of Kawase et al. (2019), we propose a procedure to correct earthquake HVSR amplitudes for direct amplification estimations. The empirical correction compensates HVSR by generic vertical amplification spectra categorized by the vertical fundamental frequency (f(0v)) via kappa-means clustering. In this investigation, we evaluate the effectiveness of the corrected HVSR in approximating observed linear amplifications in comparison with 1DSH modellings. We select a total of 90 KiK-net (Kiban Kyoshin network) surface-downhole sites which are found to have no velocity contrasts below their boreholes and thus of which surface-to-borehole spectral ratios (SBSRs) can be taken as their empirical transfer functions (ETFs). 1DSH-based theoretical transfer functions (TTFs) are computed in the linear domain considering uncertainties in Vs profiles through randomizations. Five goodness-of-fit metrics are adopted to gauge the closeness between observed (ETF) and predicted (i.e., TTF and corrected HVSR) amplifications in both amplitude and spectral shape over frequencies from f(0) to 25 Hz. We find that the empirical correction to HVSR is highly effective and achieves a "good match" in both spectral shape and amplitude at the majority of the 90 KiK-net sites, as opposed to less than one-third for the 1DSH modelling. In addition, the empirical correction does not require a velocity model, which GRAs require, and thus has great potentials in seismic hazard assessments.},
  language  = {en}
}
@article{DietzeKrautblatterIllienetal.2021,
  author    = {Dietze, Michael and Krautblatter, Michael and Illien, Luc and Hovius, Niels},
  title     = {Seismic constraints on rock damaging related to a failing mountain peak},
  series = {Earth surface processes and landforms},
  volume    = {46},
  journal   = {Earth surface processes and landforms},
  number    = {2},
  publisher = {Wiley},
  address   = {Hoboken},
  issn      = {0197-9337},
  doi       = {10.1002/esp.5034},
  pages     = {417 -- 429},
  year      = {2021},
  abstract  = {Large rock slope failures play a pivotal role in long-term landscape evolution and are a major concern in land use planning and hazard aspects. While the failure phase and the time immediately prior to failure are increasingly well studied, the nature of the preparation phase remains enigmatic. This knowledge gap is due, to a large degree, to difficulties associated with instrumenting high mountain terrain and the local nature of classic monitoring methods, which does not allow integral observation of large rock volumes. Here, we analyse data from a small network of up to seven seismic sensors installed during July-October 2018 (with 43 days of data loss) at the summit of the Hochvogel, a 2592 m high Alpine peak. We develop proxy time series indicative of cyclic and progressive changes of the summit. Modal analysis, horizontal-to-vertical spectral ratio data and end-member modelling analysis reveal diurnal cycles of increasing and decreasing coupling stiffness of a 260,000 m(3) large, instable rock volume, due to thermal forcing. Relative seismic wave velocity changes also indicate diurnal accumulation and release of stress within the rock mass. At longer time scales, there is a systematic superimposed pattern of stress increased over multiple days and episodic stress release within a few days, expressed in an increased emission of short seismic pulses indicative of rock cracking. Our data provide essential first order information on the development of large-scale slope instabilities towards catastrophic failure. (c) 2020 The Authors. Earth Surface Processes and Landforms published by John Wiley \& Sons Ltd},
  language  = {en}
}
@misc{DietzeKrautblatterIllienetal.2021,
  author    = {Dietze, Michael and Krautblatter, Michael and Illien, Luc and Hovius, Niels},
  title     = {Seismic constraints on rock damaging related to a failing mountain peak},
  series = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  journal   = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  number    = {2},
  issn      = {1866-8372},
  doi       = {10.25932/publishup-56878},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-568787},
  pages     = {15},
  year      = {2021},
  abstract  = {Large rock slope failures play a pivotal role in long-term landscape evolution and are a major concern in land use planning and hazard aspects. While the failure phase and the time immediately prior to failure are increasingly well studied, the nature of the preparation phase remains enigmatic. This knowledge gap is due, to a large degree, to difficulties associated with instrumenting high mountain terrain and the local nature of classic monitoring methods, which does not allow integral observation of large rock volumes. Here, we analyse data from a small network of up to seven seismic sensors installed during July-October 2018 (with 43 days of data loss) at the summit of the Hochvogel, a 2592 m high Alpine peak. We develop proxy time series indicative of cyclic and progressive changes of the summit. Modal analysis, horizontal-to-vertical spectral ratio data and end-member modelling analysis reveal diurnal cycles of increasing and decreasing coupling stiffness of a 260,000 m(3) large, instable rock volume, due to thermal forcing. Relative seismic wave velocity changes also indicate diurnal accumulation and release of stress within the rock mass. At longer time scales, there is a systematic superimposed pattern of stress increased over multiple days and episodic stress release within a few days, expressed in an increased emission of short seismic pulses indicative of rock cracking. Our data provide essential first order information on the development of large-scale slope instabilities towards catastrophic failure. (c) 2020 The Authors. Earth Surface Processes and Landforms published by John Wiley \& Sons Ltd},
  language  = {en}
}
@article{ZhuCottonKawaseetal.2022,
  author    = {Zhu, Chuanbin and Cotton, Fabrice and Kawase, Hiroshi and H{\"a}ndel, Annabel and Pilz, Marco and Nakano, Kenichi},
  title     = {How well can we predict earthquake site response so far?},
  series = {Earthquake spectra : the professional journal of the Earthquake Engineering Research Institute},
  volume    = {38},
  journal   = {Earthquake spectra : the professional journal of the Earthquake Engineering Research Institute},
  number    = {2},
  publisher = {Sage Publ.},
  address   = {Thousand Oaks},
  issn      = {8755-2930},
  doi       = {10.1177/87552930211060859},
  pages     = {1047 -- 1075},
  year      = {2022},
  abstract  = {Earthquake site responses or site effects are the modifications of surface geology to seismic waves. How well can we predict the site effects (average over many earthquakes) at individual sites so far? To address this question, we tested and compared the effectiveness of different estimation techniques in predicting the outcrop Fourier site responses separated using the general inversion technique (GIT) from recordings. Techniques being evaluated are (a) the empirical correction to the horizontal-to-vertical spectral ratio of earthquakes (c-HVSR), (b) one-dimensional ground response analysis (GRA), and (c) the square-root-impedance (SRI) method (also called the quarter-wavelength approach). Our results show that c-HVSR can capture significantly more site-specific features in site responses than both GRA and SRI in the aggregate, especially at relatively high frequencies. c-HVSR achieves a "good match" in spectral shape at similar to 80\%-90\% of 145 testing sites, whereas GRA and SRI fail at most sites. GRA and SRI results have a high level of parametric and/or modeling errors which can be constrained, to some extent, by collecting on-site recordings.},
  language  = {en}
}
@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}
}