In this paper, the near-field synthetic seismogram for vertical strike slip fault and dip slip fault is discussed with finite difference method in the case of different source depth and fault rupture size (refer to fault rupture size perpendicular to the ground). The acceleration fourier spectrum of different epicentral distance is discussed too.
The following inital results have been obtained through analysing near-field effect of two kinds of sources:
(1) If the source depth and the fault rupture size, are the same, the effect of vertical strike slip fault on near-field surface is larger than the effect of vertical dip slip fault.
(2) For vertical dip slip fault, if the source depth and the fault rupture size are the same, the largest amplitude of the horizontal displacement is larger than one of the vertical displacement in the same epicentral distance.
(3) The largest displacement amplitude produced by anyone of two kinds of sources in the same epicentral distance increases along with the enlargement of rupture size.
(4) The largest displacement amplitude produced by anyone of two kinds of sources in different epicentral distance decreases along with the increasing of epicentral distance, the rate of change along with the increasing of epicentral distance decreases too.
(5) The dominant period of acceleration fourie rspectrum produced by anyone of two kinds of sources in different epicentral distance changes longer along with the increasing of epicentral distance, the dominant period changes longer too along with the increasing of fault rupture size, and long period composition is much too along with the increasing of rupture size.
(6) For anyone of two kinds of sources, owing to the different source depth, the effect on near-field surface is different too. The largest displacement amplitude along with the rate of change of epicentral distance decreases, namely, isoseisms is getting thin. This relation is very useful in determing source depth by isoseisms density.
(7) The dominant period of acceleration fourier spectrum produced by vertical strike slip fault is longer than dip slip fault.