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Ground-motion models for Vrancea intermediate-depth earthquakes

Elena Florinela Manea, Carmen Ortanza Cioflan and Laurentiu Danciu
Ground-motion models for Vrancea intermediate-depth earthquakes
Earthquake Spectra (February 2022) 38 (1): 407-431


A newly compiled high-quality ground-shaking dataset of 207 intermediate-depth earthquakes recorded in the Vrancea region of the south-eastern Carpathian mountains in Romania was used to develop region-specific empirical predictive equations for various intensity measures: peak ground acceleration, peak ground velocity, and 5%-damped pseudo-spectral acceleration up to 10 s. Besides common predictor variables (e.g. moment magnitude, depth, hypocentral distance, and site conditions), additional distance scaling parameters were added to describe the specific attenuation pattern observed at the stations located not only on the back and fore but also along the Carpathian arc. In this model, we introduce a proxy measure for the site as the fundamental frequency of resonance to characterize the site response at each recording seismic station beside the soil classes. To additionally reduce the site-to-site variability, a non-ergodic methodology was considered, resulting in a lower standard deviation of about 25%. Statistical evaluation of the newly proposed ground-motion models indicates robust performance compared to regional observations. The model shows significant improvements in describing the spatial variability (at different spectral ordinates), particularly for the fore-arc area of the Carpathians where a deep sedimentary basin is located. Furthermore, the model presented herein improves estimates of ground shaking at longer spectral ordinates (>1 s) in agreement with the observations. The proposed ground-motion models are valid for hypocentral distances less than 500 km, depths over 70 km and within the moment magnitude range of 4.0-7.4.

ISSN: 8755-2930
EISSN: 1944-8201
Serial Title: Earthquake Spectra
Serial Volume: 38
Serial Issue: 1
Title: Ground-motion models for Vrancea intermediate-depth earthquakes
Affiliation: National Institute for Earth Physics, Magurele, Romania
Pages: 407-431
Published: 202202
Text Language: English
Publisher: Earthquake Engineering Research Institute, Berkeley, CA, United States
References: 84
Accession Number: 2022-015276
Categories: Seismology
Document Type: Serial
Bibliographic Level: Analytic
Annotation: Includes appendices
Illustration Description: illus. incl. 1 table, sketch map
N45°55'00" - N45°55'00", E26°53'60" - E26°53'60"
Secondary Affiliation: ETH Zurich, CHE, Switzerland
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2022, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 202206
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