Advances and limitations of the Environmental Seismic Intensity scale (ESI 2007) regarding near-field and far-field effects from recent earthquakes in Greece: implications for the seismic hazard assessment
I. D. Papanikolaou, D. I. Papanikolaou, E. L. Lekkas, 2009. "Advances and limitations of the Environmental Seismic Intensity scale (ESI 2007) regarding near-field and far-field effects from recent earthquakes in Greece: implications for the seismic hazard assessment", Palaeoseismology: Historical and Prehistorical Records of Earthquake Ground Effects for Seismic Hazard Assessment, K. Reicherter, A. M. Michetti, P. G. Silva
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The new Environmental Seismic Intensity scale (ESI 2007), introduced by INQUA, incorporates the advances and achievements of palaeoseismology and earthquake geology and evaluates earthquake size and epicentre solely from the earthquake environmental effects (EEE). This scale is tested and compared with traditional existing scales for the 1981 Alkyonides earthquake sequence in the Corinth Gulf (Ms=6.7, Ms=6.4, Ms=6.3), the 1993 Pyrgos event (Ms=5.5) and the 2006 Kythira event (Mw=6.7). These earthquakes were of different magnitudes, focal mechanisms and focal depths and produced well-documented environmental effects. The ESI 2007 intensity values and the isoseismal pattern for the 1993 Pyrgos and the 2006 Kythira events are similar to those resulting from the traditional scales, demonstrating that for moderate intensity levels (VII and VIII) the ESI 2007 and the traditional scales comply well. In contrast, the 1981 Alkyonides earthquake sequence shows that there is an inconsistency between the ESI 2007 and the traditional scales both in the epicentral area, where higher ESI 2007 intensity values have been assigned, and for the far-field effects. The ESI 2007 scale offers higher objectivity in the process of assessing macroseismic intensities, particularly in the epicentral area, than traditional intensity scales that are influenced by human parameters. The ESI 2007 scale follows the same criteria–environmental effects for all events and can compare not only events from different settings, but also contemporary and future earthquakes with historical events. A reappraisal of historical earthquakes so as to constrain the ESI 2007 scale may prove beneficial for seismic hazard assessment by reducing the uncertainty implied in the attenuation laws, which constitute one of the most important seismic hazard parameters.
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Palaeoseismology: Historical and Prehistorical Records of Earthquake Ground Effects for Seismic Hazard Assessment
Given the tremendous toll in human lives and attendant economic losses, it is appropriate that scientists are working hard to understand better earthquakes, with the aim of forecasting and, ultimately, predicting them.
In the last decades increasing attention has been paid to the coseismic effects on the natural environment, creating a solid base of empirical data for the estimation of source parameters of strong earthquakes based on geological observations. The recently introduced INQUA scale (Environmental Seismic Intensity–ESI 2007 Scale) of macroseismic intensity clearly shows how the systematic study of earthquake surface faulting, coseismic liquefaction, tsunami deposits and other primary and secondary ground effects can be integrated with “traditional” seismological and tectonic information to provide a better understanding of the seismicity level of an area and the associated hazards. At the moment this is the only scientific means of equating the seismic records to the seismic cycle time-spans extending the seismic catalogues even to tens of thousands of years, improving future seismic hazard analyses.
This Special Publication covers some of the latest multidisciplinary work undertaken to achieve that aim. Eighteen papers from research groups from all continents address a wide range of topics related both to palaeoseismological studies and assessment of macroseismic intensity based only on the natural phenomena associated with an earthquake.