Re-assessing the intensity values of Iranian earthquakes using EMS and ESI scales
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ORIGINAL PAPER
Re-assessing the intensity values of Iranian earthquakes using EMS and ESI scales H. Amini 1 & M. Zare 2 & P. Gasperini 3
Received: 19 January 2016 / Accepted: 28 September 2017 # Saudi Society for Geosciences 2017
Abstract Iran is a region with high seismicity but reliable seismometric networks were installed in this country only in the last decades. Hence, the analysis of macroseismic effects (seismic intensity) could be the only possible way for defining the parameters of most Iranian earthquakes. Various authors reported the intensity estimates of earthquakes in this region using different macroseismic scales. To apply modern methods of determining macroseismic parameters, intensity values need to be expressed in a uniform scale. In this study, we attempt such homogenization by considering all information we can find from the literature consisting of both descriptions of effects and intensity values to build a dataset of intensities for the Iran region as most complete as possible. We adopted the European Macroseismic Scale (EMS) as the reference scale as it is the most recent one and particularly detailed on building damage. We also considered the Environmental Seismic
* M. Zare [email protected] H. Amini [email protected] P. Gasperini [email protected] 1
International Institute of Earthquake Engineering and Seismology, Tehran, Iran
2
Department of Seismology, International Institute of Earthquake Engineering and Seismology, Tehran, Iran
3
Dipartimento di Fisica e Astronomia, Università di Bologna, Bologna, Italy
Intensity (ESI) scale in order to use information on environmental effects (ground deformation, landslides, liquefaction, etc.) that are poorly detailed by EMS. We compare our application of two scales based on a dataset of Iranian earthquakes for which we have descriptions of effects on both building (EMS) and environment (ESI), and found that, in about 80% of cases, assessed EMS and ESI intensities coincide one to other within one degree, that is the uncertainty which can be reasonably assumed for standard intensity estimates. In cases where we were not able to find the original descriptions of effects in literature and only intensity estimates reported in various scales, we convert these values by table of correspondence. In summary, we assessed intensities in a homogeneous scale for 512 Iranian earthquakes from 658 through 2013. Keywords Iranian earthquakes . Intensity scale . EMS and ESI scale
Introduction Intensity is a non-instrumental measure of ground motion based on the effects of the earthquakes on humans, objects, buildings, and environment at a given site. One advantage of intensity is that no instruments are required to measure it. Intensity can especially be used to determine the location and size of the earthquakes (e.g., Gasperini et al. 1999) that occurred when or where there were no available instruments. As intensity scales are discrete in nature, their degrees are usually represented by Roman numerals (e.g., VI, IX, etc.). For each degree, each
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