Title: Width of surface rupture zone for thrust earthquakes. Implications for earthquake fault zoning.
Abstract:Abstract. The characteristics of the zones of coseismic surface faulting along thrust faults are analysed in order to define the criteria for zoning the Surface Fault Rupture Hazard (SFRH) along thrus...Abstract. The characteristics of the zones of coseismic surface faulting along thrust faults are analysed in order to define the criteria for zoning the Surface Fault Rupture Hazard (SFRH) along thrust faults. Normal and strike-slip faults have been deeply studied in the past concerning SFRH, while thrust faults have not been studied with comparable attention. Surface faulting data were collected from 10 well-studied historic thrust earthquakes occurred globally (5.4 ≤ M ≤ 7.9). Several different types of coseismic fault scarps characterise the analysed earthquakes, depending on the topography, fault geometry and near-surface materials (simple and hanging wall collapse scarps; pressure ridges; fold scarps and thrust or pressure ridges with bending-moment or flexural-slip secondary faults due to large-scale folding). For all the earthquakes, the distance of secondary ruptures from the main fault (r) and the width of the rupture zone (WRZ) were collected directly from the literature or measured systematically in GIS-georeferenced published maps. Overall, surface ruptures can occur up to large distances from the main fault (~ 750 m on the footwall and ~ 1600 m on the hanging wall). Most of them occur on the hanging wall, preferentially in the vicinity of the main fault trace (Read More