New developments in onshore paleoseismic methods, and their impact on Quaternary tectonic studies

Revealing Subtle Active Tectonic Deformation: Integrating Lidar, Photogrammetry, Field Mapping, and Geophysical Surveys to Assess the Late Quaternary Activity of the Sava Fault (Southern Alps, Slovenia)

“…The restraining band comprises four reverse fault segments, with the southernmost one, the Cerklje segment, traversing and deforming a Quaternary alluvial fan, producing a 3.5 km long and up to 5 m high fault scarp [23]. [22,31], instrumental and historical earthquakes are from ESHM20 database [16], focal mechanisms Mw ≥ 5 [32][33][34][35], 1348 earthquake epicenter marked with yellow star is from the latest study of archive data [36], evidence for coseismic environmental effects associated to historical earthquakes are slope failures in Dobrač (1) and Veliki vrh (2), and archaeoseismological evidence from Celeia (3), basemap is from Copernicus DEM 1.1, inset map with location of the study area using ESRI World Terrain Base. (B)-Sava Fault traces between the Upper Sava Valley and Sava Folds; extent of glaciers in the last glacial maximum (modified from [37]), basemap is from Copernicus DEM 1.1.…”

“…To define the fault slip rate it is crucial to use the total displacement across the fault, because partial capture of deformation would give an underestimate of deformation rates. On the other hand, it is important to understand the distribution of deformation in the fault zone (e.g., [1,125,126]). The age of the top surface of the Povlje alluvial fan was estimated at 27.4 ± 1.6 ka based on one OSL date.…”

“…High-resolution digital elevation models (DEMs) acquired using lidar and photogrammetric surveys have become a valuable part of studies estimating the rate of fault activity (e.g., [1]). They are even more useful in high-relief areas with high precipitation and erosion rates, dense vegetation, and low fault slip rates, where geomorphic indicators of fault activity tend to disappear rapidly or are reshaped by non-tectonic processes [2].…”

Discovery of an Active Forearc Fault in an Urban Region: Holocene Rupture on the XEOLXELEK‐Elk Lake Fault, Victoria, British Columbia, Canada

“…Additionally, using historical imagery can prove very useful where urban development may hide previously visible fault scarps. Once a potentially active fault is identified, it is also important to consider a multifaceted approach to a paleoseismic investigation (e.g., Camelbeeck & Meghraoui, 1998;McCalpin et al, 2023;Sherrod et al, 2008;Vanneste et al, 2001). Paleoseismic trenching is a pivotal and essential method needed to verify the existence of Quaternary rupture on faults such as the XELF, and without the use of shallow geophysics (ERT) in conjunction with field mapping, we would have not been able to discern the dip and vertical separation of the fault.…”

“…These data are essential for fault-source models in probabilistic seismic hazard analysis (PSHA) and probabilistic fault displacement hazard analysis (PFDHA) (e.g., Brune, 1968;Chartier et al, 2017;Coppersmith & Youngs, 2000;Youngs & Coppersmith, 1985;Youngs et al, 2003), which are used in the seismic risk models that inform building codes and disaster management. Consequently, the integration of multiple modern paleoseismic techniques (e.g., lidar-derived high-resolution topography, shallow geophysics, and paleoseismic trenching; Camelbeeck & Meghraoui, 1998;McCalpin et al, 2023;Sherrod et al, 2008;Vanneste et al, 2001) is necessary to characterize active structures in forearcs.…”