Pavlides,S. (1), Papadopoulos,
G.A. (2) and Ganas, A.(3)
(1) Department of Geology,
University of Thessaloniki, 54006 Thessaloniki, Greece
(2) Institute of Geodynamics
, National Observatory of Athens, 20048 Athens, Greece
THE STRONG EARTHQUAKE OF 7 SEPTEMBER, 1999 IN ATHENS
On 11:56:50 of 7th September ,1999, a strong shallow earthquake of Ms = 5.9 caused heavy destruction and a death toll of about 140 to the north of Athens , Greece, at a distance of about 15 - 20 km from the city centre . The meizoseismal area is localized in the towns of Ano Liossia and Aharnes where intensities of VIII and locally IX degree (MM) were observed. The earthquake source, located at the south foot of Mt Parnes, has never been known in the past to have activated with such a strong earthquake. Therefore, it is of crucial importance to investigate the seismogenic fault and its characteristics. A field survey contacted immediately after the earthquake incorporated fault mapping and mascroseismic observations. Results concerning fault mapping , intensity distribution and ground failures observed in the meizoseismal area, such as rock falls, separations in preexisting fault surfaces, small scale landslides and local ground fissures, combined with satellite images and fault plane solutions of the main shock, imply that the seismogenic structure consists of a normal fault and its antithetic striking N110°- 130° from the Fyli Castle to the WNW to Fyli town and then to Ano Liossia to the ESE. Tensional stress field with the ó3 axis striking NNE to SSW prevails in the area. A segment of 5 km in length of this tectonic structure is mapped in the existing geological map (scale 1:50,000) of the area and it is classified as an inactive normal fault. Typical surface fault traces were not observed. The length of the visible, mapped surface seismic zone is about 8 km with a possible non-visible segment of a length of about 2-5 km in the area of Aharns.