Rupture terminations and size of segment boundaries from historical earthquake ruptures in the Basin and Range Province

The fault-segmentation method is commonly used to estimate the potential earthquake size. Segment boundaries play an important role in arresting earthquake ruptures from event to event. In the Basin and Range Province, earthquake rupture terminations are commonly associated with structural discontinuities, but not all-structural discontinuities have the capability to terminate an earthquake rupture. The size of structural discontinuities with respect to the rupture length and displacement may play an important role in controlling rupture termination. Studies of the geometric pattern of seven well-documented historical earthquake ruptures in the Basin and Range Province reveal three important relationships between rupture termination and the size of structural discontinuities. Firstly, terminations of normal faulting earthquakes are often associated with structural discontinuities, at least for the five historical ruptures studied in this paper. Secondly, the sizes of structural discontinuities at the end of earthquake rupture zones are generally the largest among the structural discontinuities within the rupture zone. Thirdly, there appears to be a trend that larger earthquake ruptures are stopped by larger structural discontinuities. The size of structural discontinuities that stopped the earthquake seems to scale with the length and displacement of earthquake surface rupture. (C) 1999 Elsevier Science B.V. All rights reserved.