Experimental investigation of strong ground motion due to thrust fault earthquakes

Abstract

(2014), Experimental investigation of strong ground motion due to thrust fault earthquakes, J. Geophys. Res. Solid Earth, 119, 1316-1336, doi:10.1002 Abstract Thrust fault earthquakes are studied in a laboratory earthquake setup previously used to investigate analog strike-slip seismic events. Dynamic mode II ruptures are generated along preexisting faults in an analog material, Homalite H-100, and their interaction with the free surface is studied for both sub-Rayleigh and supershear rupture speeds. High-speed digital photography and laser velocimeter diagnostics are used synergistically to identify and study the ground velocity signatures caused by the various features of the generated ruptures. The obtained surface-normal motions of both sub-Rayleigh and supershear ruptures show substantial asymmetry between the hanging and footwall, with the hanging wall experiencing much larger velocity amplitudes. The main features of the surface velocity traces at various stations can be explained by the calculated arrivals of various waves and fronts-Mach cones, P and S waves, and sub-Rayleigh features. In both the sub-Rayleigh and supershear cases, the arrival of the rupture tip generates a prominent Rayleigh wave traveling along the simulated Earth's surface. Supershear events feature larger amplitudes of ground shaking profiles. All signatures in the surface motion records attenuate and broaden with increasing distance from the fault trace. The signatures corresponding to the arrival of the Mach fronts attenuate with distance at a slower rate than those from sub-Rayleigh ruptures. The arrival of the updip supershear rupture at the free surface creates a downdip propagating slip feature with its own Mach cone. These additional Mach fronts further amplify ground shaking on the hanging and footwalls.

Analogue earthquakes and seismic cycles: experimental modelling across timescales

“…Several numerical studies confirmed their results (Oglesby et al, 1998(Oglesby et al, , 2000aMa and Beroza, 2008;Nielsen, 1998;Gabuchian et al, 2017). Gabuchian et al (2014Gabuchian et al ( , 2017 most recently revisited this issue by means of experiments using homalite as a rock analogue. Beside the free-surface effects they focused on rupture velocity as a controlling factor for ground motion.…”

Control of style-of-faulting on spatial pattern of earthquake-triggered landslides

“…The logic of studying the distribution of ETLs on the hanging-wall of faults is based on findings that, during earthquakes, ground motions are stronger on the hanging-wall than on the footwall of a dipping earthquake fault (Abrahamson and Somerville 1996;Yu and Gao 2001;Ulusay et al 2004). The proposed explanation for those observations is asymmetry of distribution of seismic energy as a function of fault geometry (Oglesby and Day 2002;Beavan et al 2012;Shi and Day 2013;Gabuchian et al 2014), although that is usually not the case because attenuation of ground motion is also a function of style-of-faulting (Campbell 1981;Abrahamson and Silva 1997;Bommer et al 2003). Nevertheless, studies have shown that ground motions on the hanging wall were stronger than on the footwall of the Yingxiu-Beichuan fault Lu et al 2010).…”

“…However, the findings must be crossexamined further in relation to fault geometry because (a) the mainly thrust-slip southern part of the YingxiuBeichuan fault has a different geometry than its mainly strike-slip northern part (Fig. 3) and (b) attenuation of ground motion is also a function of fault geometry (Oglesby and Day 2002;Beavan et al 2012;Shi and Day 2013;Gabuchian et al 2014). In addition, the findings must be cross-examined further in relation to other factors that influence variations in ground motion (see Campbell (1981Campbell ( , 1997).…”

“…Wu and Chen 2011;Huang et al 2012;Huang and Fan 2013;. Based on two-and three-dimensional dynamic simulations of dipping faults, for the same initial stress magnitude, thrust (or reverse dip-slip) faults can produce much higher fault and ground motion than normal and strike-slip faults (Oglesby and Day 2002;Beavan et al 2012;Shi and Day 2013;Gabuchian et al 2014). Considering that landslides are important components of a geomorphic system, Scheidegger (2001) emphasized that ongoing tectonic movements, especially neo-tectonic processes, have much more profound influence on geomorphic systems and, thus, on landslide formation than the generally assumed factors of geomorphic development.…”

Supershear rupture in the 24 May 2013 Mw 6.7 Okhotsk deep earthquake: Additional evidence from regional seismic stations

“…Observations and understanding of supershear ruptures have important implications for seismic hazard and earthquake dynamics [Dunham et al, 2003;Xia et al, 2004;Dunham, 2007;Das, 2010;Mello et al, 2010;Schmedes et al, 2010]. For example, Gabuchian et al [2014] show that upward supershear rupture on a thrust fault would enhance the ground shaking by a factor of 2 to 3. Although the physics and conditions of the transition from subshear (V r < V S ) to supershear rupture are not yet fully understood, previous observations and theoretical studies indicate that high prestress and high seismic efficiency (e.g., a simple fault geometry) help promote supershear rupture [Zhang and Chen, 2006;Bouchon et al, 2010;Kaneko and Lapusta, 2010].…”