Shear‐wave velocity based seismic microzonation of Lorca city (SE Spain) from MASW analysis

2014 ◽  
Vol 12 (6) ◽  
pp. 739-750 ◽  
Author(s):  
P. Martínez‐Pagán ◽  
M. Navarro ◽  
J. Pérez‐Cuevas ◽  
F.J. Alcalá ◽  
A. García‐Jerez ◽  
...  
Author(s):  
P. Martinez-Pagan ◽  
M. Navarro ◽  
J. Pérez-Cuevas ◽  
A. García-Jerez ◽  
F.J. Alcalá ◽  
...  

2021 ◽  
Author(s):  
Gino Romagnoli ◽  
Gianluca Carbone ◽  
Stefano Catalano ◽  
Massimo Cesarano ◽  
Stefania Fabozzi ◽  
...  

<p>The availability of a unique database, where all data of the seismic microzonation studies carried out in about 1900 municipalities of Italy (https://www.webms.it/) are achieved with a standardized format, allowed statistical elaborations in terms of subsoil parameters. In particular, we analysed borehole logs and geophysical data in order to characterize them with the shear wave velocity (Vs) vertical profile, and the code of standardized engineering geological units, according to the Italian Guidelines for Seismic Microzonation (Seismic Microzonation Working Group, 2015; 2018). The Vs parameter, extracted from about 3700 geophysical surveys, was correlated to the engineering geological units from the borehole logs, with 1meter step. The correlation was performed for about 1700 available Down-Hole (DH) surveys and for about 2000 Multichannel Analyses of Surface Waves (MASW). For these latter, we selected only MASW surveys located near boreholes, no more than 100 m away. The statistical analysis on the distribution and dispersion of Vs parameter allowed to calculate the Vs values related to the mode, mean, median, standard deviation, first quartile, third quartile, minimum and maximum, and the trend with depth of Vs for each engineering geological unit. Validation with external datasets (e.g. Italian Vs30 map, Mori et al., 2020) demonstrates that the characterization of engineering geological units in term of Vs, based on velocity profiles extracted by the Italian seismic microzonation dataset, allow to reliably characterize the engineering geological model, where no geophysical data are available. Statistics of subsoil parameters will represent a fundamental tool for computing local seismic ground motion parameters (e.g. PGA, H<sub>SM</sub>) in the areas not covered by seismic microzonation studies.</p><p><strong>References</strong></p><p>- Mori, F., Mendicelli, A., Moscatelli, M., Romagnoli, 796 G., Peronace, E., Naso, G., 2020. A new Vs30 map for Italy based on the seismic microzonation dataset. Engineering Geology 275, 105745. https://doi.org/10.1016/j.enggeo.2020.105745.</p><p>- Seismic Microzonation Working Group, 2015. Guidelines for Seismic Microzonation http://www.protezionecivile.gov.it/httpdocs/cms/attach_extra/GuidelinesForSeismicMicrozonation.pdf</p><p>- Seismic Microzonation Working Group, 2018. Standard di rappresentazione e archiviazione informatica Versione 4.1. http://www.protezionecivile.gov.it/attivita-rischi/rischio-sismico/attivita/commissione-supporto-monitoraggio-studi-microzonazione/standard-rappresentazione-archiviazione-informatica</p>


2018 ◽  
Vol 16 (3) ◽  
pp. 356-371 ◽  
Author(s):  
Pedro Martínez-Pagán ◽  
Manuel Navarro ◽  
Jaruselsky Pérez-Cuevas ◽  
Francisco J. Alcalá ◽  
Antonio García-Jerez ◽  
...  

2021 ◽  
Author(s):  
Stefania Fabozzi ◽  
Stefano Catalano ◽  
Giuseppe Naso ◽  
Alessandro Pagliaroli ◽  
Edoardo Peronace ◽  
...  

<p>The seismic subsoil response in terms of amplification or attenuation of the ground motion is the result of a complex combination of factors, including the vertical and horizontal subsoil heterogeneities (Fabozzi et al., 2021). In volcanic areas in particular, the vertical subsoil heterogeneities are well identified by characteristic superposition of stiffer volcanic horizons on softer levels, giving rise to stiff-soft alternating layers, also in the form of multiple Vs inversions with the depth. This condition is typical of sheet-like blankets of lava or pyroclastic deposits, extensively covering the sedimentary substratum, frequent in the peripheral areas of large basaltic stratovolcanos or in areas adjacent to large explosive acidic volcanic edifices. The aim of the present work is to study the effect of such vertical heterogeneities on the seismic site response. With this end, in correspondence of volcanic areas identified by means of a preliminary geological screening in the Italian territory, subsoil properties relevant for seismic site response analyses were extracted from the Italian database of the seismic microzonation studies (DB-SMs in DPC, 2018), which is available at www.webms.it and is developed and maintained by CNR IGAG (National Research Council of Italy, Institute of Environmental Geology and Geoengineering, www.igag.cnr. it). The collection of input data was used for an extensive one-dimensional equivalent linear numerical site response analyses, in order to evaluate the influence of stiffness inversions on ground motion at surface. In particular, different idealized subsoil 1D models of the identified geological areas were defined in terms of variation of layers thickness, shear wave velocity and nonlinear properties. The effect of the variability of these parameters on the seismic site response in terms of amplification factors (ICMS, 2008) was studied parametrically.</p><p><strong>References </strong></p><ul><li>DPC, Dipartimento della Protezione Civile, 2018. Commissione tecnica per il supporto e monitoraggio degli studi di Microzonazione Sismica (ex art.5, OPCM3907/10), (2018) WebMs; WebCLE. A cura di: Maria Sole Benigni, Fabrizio Bramerini, Gianluca Carbone, Sergio Castenetto, Gian Paolo Cavinato, Monia Coltella, Margherita Giuffrè, Massimiliano Moscatelli. In: Giuseppe Naso. Andrea Pietrosante, Francesco Stigliano.</li> <li>Fabozzi S., Catalano S., Falcone G., Naso G., Pagliaroli A., Peronace E., Porchia A., Romagnoli G., Moscatelli M. (2021) Stochastic approach to study the site response in presence of shear wave velocity inversion: application to seismic microzonation studies in Italy. Engineering Geology https://doi.org/10.1016/j.enggeo.2020.105914.</li> <li>ICMS, 2008. Indirizzi e Criteri per la Microzonazione Sismica. In: Gruppo di lavoro ICMS. Conferenza Delle Regioni E Province Autonome - Dipartimento Della Protezione Civile. https://www.centromicrozonazionesismica.it/it/download/category/7-indi rizzi-e-criteri-per-lamicrozonazione-sismica (In Italian).</li> </ul>


Solid Earth ◽  
2019 ◽  
Vol 10 (2) ◽  
pp. 379-390 ◽  
Author(s):  
Yaniv Darvasi ◽  
Amotz Agnon

Abstract. Instrumental strong motion data are not common around the Dead Sea region. Therefore, calibrating a new attenuation equation is a considerable challenge. However, the Holy Land has a remarkable historical archive, attesting to numerous regional and local earthquakes. Combining the historical record with new seismic measurements will improve the regional equation. On 11 July 1927, a rupture, in the crust in proximity to the northern Dead Sea, generated a moderate 6.2 ML earthquake. Up to 500 people were killed, and extensive destruction was recorded, even as far as 150 km from the focus. We consider local near-surface properties, in particular, the shear-wave velocity, as an amplification factor. Where the shear-wave velocity is low, the seismic intensity far from the focus would likely be greater than expected from a standard attenuation curve. In this work, we used the multichannel analysis of surface waves (MASW) method to estimate seismic wave velocity at anomalous sites in Israel in order to calibrate a new attenuation equation for the Dead Sea region. Our new attenuation equation contains a term which quantifies only lithological effects, while factors such as building quality, foundation depth, topography, earthquake directivity, type of fault, etc. remain out of our scope. Nonetheless, about 60 % of the measured anomalous sites fit expectations; therefore, this new ground-motion prediction equation (GMPE) is statistically better than the old ones. From our local point of view, this is the first time that integration of the 1927 historical data and modern shear-wave velocity profile measurements improved the attenuation equation (sometimes referred to as the attenuation relation) for the Dead Sea region. In the wider context, regions of low-to-moderate seismicity should use macroseismic earthquake data, together with modern measurements, in order to better estimate the peak ground acceleration or the seismic intensities to be caused by future earthquakes. This integration will conceivably lead to a better mitigation of damage from future earthquakes and should improve maps of seismic hazard.


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