The 2013 Lushan earthquake: Implications for seismic hazards posed by the Range Front blind thrust in the Sichuan Basin, China

Abstract

This file includes figures, tables, models divided into seven Data Repository (DR) items: 2013); Q4, Holocene. We highlight the uplift of Q2 (middle Pleistocene Ya'an Formation) and its corresponding age, and then translate this uplift to a slip based on the relationship from Shaw et al., (2002) assuming a fault dip of 33-56°. Final, we obtain the range of slip rate for the RFBT to be 0.13-0.39 mm/yr. Figure DR4: Interpretation of industry seismic reflection profile L2 in the Sichuan basin, modified from our previous study by Jia et al., (2010). The large rectangle denotes the locations of Figure 4a, showing the hanging wall deformation associated with the RFBT. The small rectangle denotes the location of shallow seismic reflection profile B, which is shown on Fig. 4b. The RFBT extends into the basin, and forms the structural wedge, with its wedge-tip at about 8-9 km. The hanging wall of the RFBT contains a kink band, which extend from the ramp to the surface. This kink band is formed by the splay fault on the RFBT, thus the growth triangle on the shallow seismic reflection profile B records the activity on the RFBT. The range of possible splay fault dips is 33°-56°, which is constrained using the dips range of the axial surface (upper limit) and the ramp dips (lower limit) on the RFBT. Figure DR5: Interpretation of industry seismic reflection profile E in the Sichuan basin. The large rectangle denotes the locations of shallow seismic reflection profile C, which is shown on Fig. 4c. A splay fault of the RFBT rises from the ramp to the near surface, and displaces geological Triassic and younger layers in the hanging wall. We interpret this fault propagates to the shallow surface, producing the tip folding, and forming two back thrusts, which are shown on shallow section C. PGT, Pengguan thrust fault; RFBT, Range Front blind thrust, J, Jurassic; T, Triassic. Data Repository Item DR6 Data Repository Item DR7

Three‐dimensional seismic velocity structure in the Sichuan basin, China

“…The M w 6.6 Lushan earthquake occurred on the Range Front blind thrust in the southern segment of the Longmen Shan thrust belt [ Wang et al ., ; Li et al ., ]. The event is one of the best recorded earthquakes in Sichuan region, because of the expansion of seismic network in the region after the 2008 Wenchuan earthquake.…”

On the evolution of seismogenic faults in the Longmen Shan, eastern Tibet

“…Southern, central and northern segments of the Longmen Shan faults are separated by white lines and aftershocks in red were selected to infer the failure planes for associated segements (Yi et al, 2012). Three purple lines marked by AA', BB' and CC' are locations of the seismic reflection profiles by Jia et al (2010) and Wang et al (2014). Three shorter yellow lines are much higher resolution reflection profiles by Wu et al, 2014 Explanation of the coseismic Beichuan and Pengguan faults (red lines) by seismic reflection data, typically characterized by low-angle imbricated overthrust geometry (Jia et al, 2006(Jia et al, , 2010Y Li et al, 2010), and our new interpretations of the high-angle fault geometry (black dashed lines) according to reflection data and the dip/depth relations for southern and northern Longmen Shan faults (Wu et al, 2014, Yi et al, 2012.…”

“…The absence of a surface rupture during the 2013 Lushan event has led to an active debate still ongoing over whether slip occurred on the Pengguan fault or on one of the faults father east in the foreland (Wang et al, 2014;Xu et al, 2013;Y Zhang et al, 2013). The close correspondence of the epicentral locations with the Pengguan fault (Shuangshi-Dachuan fault) suggest that this event was also possibly hosted along a relatively steep structure (Figures 1 and 5; Y Zhang et al, 2013).…”

“…Those early events, although maybe slightly bigger than the Lushan earthquake, were mostly resulted from the slip along the high-angle Pengguan fault, identical to the latest 2013 event ( shortening along faults within the basin. It appears that many of these structures root into a subhorizontal décollement at < 10 km Wang et al, 2014), and it appears that this structure f at the Longmen Shan range front remains active during shortening along high-angle faults further into the interior Longmen Shan range.…”

“…Reinterpretation of the high-angle coseismic Shuangshi-Dachuan (Pengguan) fault (black dashed line) (Y, crosscutting low-angle imbricated overthrust faults revealed by seismic reflection data(Wang et al, 2014).…”