Fault Displacement Hazard for Strike-Slip Faults

Abstract

In this paper we present a methodology, data, and regression equations for calculating the fault rupture hazard at sites near steeply dipping, strike-slip faults. We collected and digitized on-fault and off-fault displacement data for 9 global strikeslip earthquakes ranging from moment magnitude M 6.5 to M 7.6 and supplemented these with displacements from 13 global earthquakes compiled by Wesnousky (2008), who considers events up to M 7.9. Displacements on the primary fault fall off at the rupture ends and are often measured in meters, while displacements on secondary (offfault) or distributed faults may measure a few centimeters up to more than a meter and decay with distance from the rupture. Probability of earthquake rupture is less than 15% for cells 200 m × 200 m and is less than 2% for 25 m × 25 m cells at distances greater than 200 m from the primary-fault rupture. Therefore, the hazard for off-fault ruptures is much lower than the hazard near the fault. Our data indicate that rupture displacements up to 35 cm can be triggered on adjacent faults at distances out to 10 km or more from the primary-fault rupture. An example calculation shows that, for an active fault which has repeated large earthquakes every few hundred years, fault rupture hazard analysis should be an important consideration in the design of structures or lifelines that are located near the principal fault, within about 150 m of well-mapped active faults with a simple trace and within 300 m of faults with poorly defined or complex traces.

Width of surface rupture zone for thrust earthquakes: implications for earthquake fault zoning

“…Scarp type classification (modified after Philip et al, 1992 andYu et al, 2010). The scarp types (h) and (i) are associated with large-scale folds (hundreds of metres to kilometres in wavelength) and are from Philip and Meghraoui (1983).…”

“…S2) was not measured. It consists of normal fault ruptures interpreted to be related to either or both of the following (Yelding et al, 1981;Philip and Meghraoui, 1983): (1) very large gravitational sliding and (2) surface response of an unconstrained deep tectonic fault also responsible for the 1954 M 6.7 earthquake. Therefore, we avoided measuring the rupture due to the large uncertainties concerning its primary origin.…”

“…The mitigation of SFRH can be faced by strategies of fault zoning and avoidance or, alternatively, by (or together with) probabilistic estimates of fault displacement hazard (e.g. Youngs et al, 2003;Petersen et al, 2011). Both strategies need to employ, as accurately as possible, the location of the active fault trace, the expected displacement on the principal fault (PF; i.e.…”

“…In general, the fault displacement hazard of normal and strike-slip faults (e.g. Youngs et al, 2003;Petersen et al, 2011) has been much more studied than that of thrust faults. Zhou et al (2010) analysed the width of the surface rupture zones of the 2008 Wenchuan earthquake focusing on the rupture zone close to the PF, with implications on the setback distance.…”

Strong Ground Motion Estimation

“…Oglesby and Day (2002), Guatteri et al (2003), and Schmedes et al (2010) used dynamic rupture simulations to demonstrate that rupture parameter correlation, as implemented in the stochastic kinematic rupture model outlined here, is necessary to produce realistic source parameters for ground motion estimation. The fault slip variability incorporates the natural log standard deviation of strike-slip displacement observed by Petersen et al (2011) in their analyses of global measurements of strike-slip fault displacements. Consequently, although mean displacements are on the order of 1.5 m for the M 7.1 three-segment scenario earthquake, asperities within the overall rupture have displacements of up to 3-4 m. The Liu et al (2006) slip velocity function is used with the specified fault slips and rise times to calculate slipvelocity time functions at each grid point.…”