The Source Mechanism of the Athens Earthquake,September 7, 1999, Estimated from P Seismograms Recorded at Long Range |
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| Authors: | Sargeant SL Burton PW Douglas A Evans JR |
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| Institution: | (1) School of Environmental Sciences, University of East Anglia, Norwich, NR4 7TJ, UK;(2) British Geological Survey, Murchison House, West Mains Road, Edinburgh, EH9 3LA, UK;(3) AWE Blacknest, Reading, RG7 4RS, UK |
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| Abstract: | On 7 September, 1999, an earthquake (5.8 mb
USGS)took place about 20 km from the centre of Athens, until then a seismically quiet region ofeastern Greece. Considerable damage ranging from rock falls to the collapse of reinforcedconcrete structures was reported in the city and surrounding area. No surface break which couldbe directly attributed to rupture on the fault plane was mapped. We use the relativeamplitude method and forward modelling of broadband P seismogramsrecorded at long range to produce a two-dimensional model of the source. We conclude that the earthquake tookplace on a south-west dipping normal fault at a depth of 10 km. This implies that the depthof the seismogenic zone in the area is comparable to other more active regions of Greece.The rupture speed (2.1 km/s) and stress drop (0.54 MPa) are low and are typical of earthquakesin a tectonic environment dominated by high rates of extension. The estimated seismicmoment is 6.014 × 1017 N m. We have investigated reported rupture directivity and thepossibility of a circular rupture is also examined. Extrapolation of the fault plane to the freesurface suggests that the earthquake took place on a structure associated with the Fili fault. |
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| Keywords: | Athens earthquake Greece source model teleseismic body wave modelling |
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