Schmidt hammer and terrestrial laser scanning (TLS) used to detect single‐event displacements on the Pleasant Valley fault (Nevada, USA)

Abstract

Changes in surface roughness on carbonate fault scarps often reflect varying durations of subaerial weathering. On the Pleasant Valley fault in central Nevada, the documentation of a surface rupture in 1915, a long recurrence interval of faulting, slow weathering rate, and a relatively high (2-3 m) single-event displacement make the discrimination of the historical and penultimate slip patches unambiguous. Following from a 2018 study, we used a Schmidt hammer and terrestrial laser scanning (TLS) to further test whether these weathering patterns delineate exposed slip patches on a fault scarp. Results show that Schmidt hammer rebound value ranges (termed ΔRthe difference between minimum and maximum R-values in repeat impacts at a point), increase by~8-10 points across the historical-penultimate event transition zone in two separate scarp transects. TLS-derived surface roughness also indicates a clear difference between the most recent and penultimate events. The average single-event displacement (SED) estimated using the Schmidt hammer and TLS is 2.85 m at two transect sites and is roughly equivalent to the visually estimated 3 m. While this fault is an ideal case where we know some of the slip history, the results demonstrate that these techniques show promise for discriminating slip patches on larger carbonate fault scarps with longer paleoearthquake histories, and could be used alongside 36 Cl cosmogenic exposure-age dating to improve paleoseismic records on normal faults.

Feasibility of Terrestrial Laser Scanning System for Detecting and Monitoring Surface Displacement of Artificial Slopes on Forest Roads

“…Recently, laser or light detection and ranging (LiDAR) scanning systems have been used to detect soil surface displacement. (20)(21)(22)(23)(24) Several laser scanning systems for different types of applications exist. Terrestrial-fixed, terrestrial-mobile, and airborne systems are classified by the types of platforms to which they are applied.…”

Identification of Paleoearthquakes and Coseismic Slips on a Normal Fault Using High-Precision Quantitative Morphology: Application to the Jiaocheng Fault in the Shanxi Rift, China

“…A well-preserved bedrock fault scarp can record a detailed paleoearthquake history and important paleoearthquake information concerning accurate coseismic slips and earthquake recurrence intervals [16][17][18][19][20], and it has become an attractive target for paleoseismological studies [21]. Over the last two decades, a great number of studies have been conducted to extract paleoearthquake information from bedrock normal faults in the grabens of the U.S.A. [16,22,23], Israel [24,25], Greece [17,[26][27][28], and Italy [29][30][31], using cosmogenic nuclide exposure dating and other physical and chemical indicators. However, only a few studies have applied these techniques to bedrock normal faults in China [32,33].…”

“…Not only can absolute dating obtain the number of individual earthquakes but also it can determine the corresponding age and slip rate by measuring the in situ cosmogenic nuclide concentrations along the fault scarp [18,19,30,[37][38][39][40][41]. The difficulties associated with this technique are that it can be prohibitively expensive, requiring a large amount of time, manpower, and materials to prepare and analyze samples at the sampling intervals required to identify seismic events [22,23,32].…”

“…Relative dating techniques assume that the degree of weathering is a function of the exposure time of bedrock fault surfaces and that the time-dependent weathering phenomena are quantifiable [23]. These methods obtain the number and coseismic slips of individual earthquakes by microroughness measurements [15,29], observing discoloration by the naked eye [42], photographic analysis [29], pit depth measurements [43], rebound value tests using a Schmidt hammer [22], lichen size measurements [44], rare earth element analysis [28,35,45], measurements of optically stimulated luminescence residual signals [46], or terrestrial laser scanning (TLS) [47].…”