P-wave spectra of the Fuzesgyarmat, eastern Hungary earthquake sequence

On 29-30 September 1996, an earthquake sequence occurred in the Fuzesgyarma t region in eastern Hungary. The main shock had a magnitude of M-L = 3.2 an d was felt with a maximum intensity 4 MSK. It was preceded by a foreshock w ith a magnitude of M-L = 2.8 and was followed, within six hours, by five af tershocks with magnitudes 2.1 less than or equal to M(L)less than or equal to 3.1. The dynamic source parameters of the Fuzesgyarmat earthquake sequen ce have been derived from P-wave spectra of the Hungarian seismograph stati ons. The average of the obtained values at different stations shows that th e main shock occurred on a fault length of 610 m, with relative displacemen t of 1.13 cm, stress drop of 7 bar and seismic moment of 3.96*10(21) dyne.c m. The main shock was small to yield data for a full mechanism solution and no reliable single fault plane solution could be obtained due to the low s ignal to noise ratio at the recording stations. The parameters of the fores hock are fault length of 560m, seismic moment of 2.09*10(21) dyne.cm, stres s drop of 5.53 bar and relative displacement of 0.73 cm. The five aftershoc ks show source parameters similar to the foreshock stress drops (5.26 less than or equal to Delta sigma less than or equal to 5.76 bar), fault lengths (415 less than or equal to L less than or equal to 600 m), seismic moments (8.36*10(20) less than or equal to M-o less than or equal to 2.31*10(21) d yne.cm) and relative displacements (0.52 less than or equal to 0 less than or equal to 0.91 cm).