by Paul Somerville
Somerville, Paul (1998). Development of An Improved Representation of Near Fault Ground Motions. SMIP98
Seminar on Utilization of Strong-Motion Data, p. 1 - 20.
Click on the link below for the full text:
The principal objective of this study is to develop an improved parameterization for the engineering
specification of near-fault ground motions. In addition to the response spectrum, we would like to
include time domain parameters that describe the near-fault pulse, such as its period, amplitude,
and number of half-cycles. We have developed a preliminary model that relates time domain parameters
of the near-fault ground motion pulse to the earthquake magnitude and distance. The model is for
forward rupture directivity conditions, which produce a strong pulse of motion in the fault-normal
direction. The pulse parameters that we have modeled are the period and peak amplitude of the
largest cycle of motion of the velocity pulse. The records analyzed include 15 time histories
recorded in the distance range of 0 to 10 km from earthquakes in the magnitude range of 6.2 to 7.3,
augmented by 12 simulated time histories that span the distance range of 3 to 10 km and the
magnitude range of 6.5 to 7.5.