THE AIGIO (GREECE) SEISMIC SEQUENCE OF JUNE 1995: SEISMOLOGICAL, STRONG MOTION DATA AND EFFECTS OF THE EARTHQUAKES ON STRUCTURES
Abstract
On 15 June 1995, an earthquake of moment magnitude Mw=6.4 occurred in the western part of Corinthiakos Gulf, Greece, causing the loss of 26 human lives and inflicting considerable damage mainly in the northern part of Peloponnessus. Particularly damaged was the town of Aigio with its environs. The only strong motion instrument in operation at the time of the mainshock in the town of Aigio recorded a horizontal acceleration as high as 0.54 g — the highest ever recorded in Greece — in the vicinity of a collapsed building. The main characteristic of the recorded strong ground motion is the pulse-like shape of its most intensive part, with a period of about 0.45 sec. The macroseismic observations are in good agreement with the distribution of the peak horizontal acceleration — recorded at epicentral distances from 18 km to 78 km, and both sets of data imply anisotropic radiation of seismic waves by the source. The tremor and its largest aftershock (Mw=5.6), which followed about 15 minutes later, caused total or partial collapse of a few buildings and heavily damaged several more. However, despite the very high recorded accelerations — the highest recorded in Greece — and the highest response spectra resulting from them, damage was not as much as one might have expected, considering the poor earthquake design and construction practices under which the majority of the buildings in the town and its surroundings had been built. This earthquake demonstrated among others, the great improvement in seismic behaviour of buildings effected by the application of the revised Greek Seismic Design Code of 1984, along with the importance of strength reserves of existing buildings in alleviating the consequences of strong ground motions.
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