3D temporal characteristics of earthquake ground motion at single point

In this paper, we present the results of a study of the temporal 3D charact eristics of earthquake ground motion at a single point, which are a complet ely different set from the frequently used spatial 3D characteristics. A gr ound motion trajectory from the 1995 Kobe earthquake is analyzed, based on the concept of temporal curvature and torsion. Kinematic turning and twisti ng of the ground motion are found to have occurred in the form of temporal curvature and torsion pulses. These pulses have typical durations of 100 or 20 ms, respectively. These two types of pulses offer some detailed charact erization of the ground acceleration behaviors.