Proceedings of the 12th International INQUA meeting on paleoseismology, active tectonic and archaeoseismology

In January 2024, we flew a Quantum Systems F90+ fixed- wing UAS that has the capablity of >60 minutes of flight time, enabling capture of 60 km of linear flight line on a single flight (Fig. 2). The UAS carried the Qube 240 LiDAR unit, a 905 nm sensor with 240,000 shots/second. We flew at ~100 m above ground level, providing ~100 points/m2 spatial density. We processed the raw data, classified points as ground vs non-ground, and created bare- earth DEMs with 0.5-m spacing using Yellowscan CloudStation. We merged DEMs from multiple flights together and generated hillshades using QGIS. Furthermore, we collected electrical resistivity tomographic data at the site in January 2023 (see Dollens et al., this meeting for details). Paleoseismic trenching was conducted during April 2022 (McEnaney et al., 2022). Trench 3 was reopened in January 2023. R E S U LT S / D I S C U S S I O N The Gualán research site is located 1.5 km east of the city and south of the Motagua River in the central Motagua Valley, approximately 35 km southwest of the 1976 earthquake epicenter (Fig. 1). The research site for this study was located using U.S.G.S. Plafker archival material of the 1976 earthquake rupture that led to the rediscovery of the offset concrete irrigation canal (McEnaney and Niemi, 2021; Niemi et al., 2022). Fig. 3: Map showing the location of the new 2024 LiDAR around the Gualán study site that is marked with a red star. The regional LiDAR image (Fig. 3) highlights the geomorphology of the Gualán area. The Motagua fault lies within lower hills and fluvial terraces that are bounded to the north and south by large mountain ranges. The fluvial terraces are composed predominantly of pumiceous alluvium that is reworked ignimbrites and tuff deposits interbedded with fluvial and alluvial fan deposits without primary ashfall tuffs (Johnson, 1984). The ridges within the Motagua valley are outcrops of the red sandstone and conglomerates of the Tertiary Subinal Formation that likely