Measuring vertical displacements from strike-slip earthquakes remains challenging as the vertical motion is small and most geodetic methods are not well suited to measure displacement in the vertical direction in the near field. Here we measure the vertical displacement caused by the M 6.4 and M 7.1 Ridgecrest Earthquakes in 2019 using post-earthquake lidar point clouds. Using the lidR package for R and the lidar point cloud, we created a code to assist in selecting cross-sections along the Ridgecrest faults to measure the vertical displacement in 100-meter-spaced increments along the surface rupture. We apply a linear fit to the top and the bottom of the scarps. The vertical separation between the best-fit lines is the vertical displacement accommodated by the fault. Our results highlight that, in flat sections along the rupture, it is possible to resolve vertical displacements from the post-earthquake lidar point clouds alone, i.e., without requiring differential lidar. We find variable vertical displacements with a maximum exceeding 2 meters, several scarps exceeding 1 meter, and most of the vertical displacements in the centimeter scale. Our preliminary results show no systematic trends in vertical displacements along strike, suggesting that the vertical displacements we measure reflect the local kinematics of the fault. This method may be used to constrain vertical displacements from other strike-slip events with post-earthquake lidar.

Waterfalls elicit a special intrigue and yet we do not fully understand how they form. They are thought to form as products of climatic and tectonic activity, and new evidence shows that many waterfalls are likely to be self-forming. We know that waterfalls erode mountains and retreat upstream. The rate at which they retreat is a key to reconstruction of past landscapes. However, without a full understanding of this retreat rate, we cannot accomplish accurate tectonic reconstruction. The self-forming qualities of waterfalls has been looked at in the homogeneous granitic landscape of the San Gabriel Mountains. To gain more understanding of this process, we need to investigate a site with more diversity in rock properties. We propose to look at the Sierra Nevada Mountains so that we may compare different rock properties in rivers that exist within a similar climate. This will deepen our understanding of historical climate and make our reconstructions of past topography more accurate. To accomplish this, we will procure high-resolution imagery of the Sierras so that we can analyze how fractured the rocks are. We will procure topographical data from the Sierras that will allow us to find the spatial signature of the rivers. We will relate the spatial signature in the Sierras to how fractured the rocks are to better understand the effects of rock properties on waterfall formation. Understanding the effects of rock properties on waterfall position, especially in the context of self-forming waterfalls, will increase our understanding of historical landscapes.

Increasing urbanization in watersheds can cause streams to become heavily degraded and polluted. This is known as urban stream syndrome which varies with the intensity of urbanization. In addition, climate directly and indirectly, impacts stream ecosystem processes however, precipitation patterns vary significantly between temperate (mild temperature) areas and arid (dry) regions. This can affect how streams respond to urbanization in their contributing watersheds because stormwater runoff carries nutrients and contaminants off of lawns, roads, and parking lots into downstream freshwater ecosystems. In urban areas, lawn irrigation and leaking pipes can increase base flow in the dry summer period in arid climates. These sources of water have different stable isotope chemical composition than the water obtained from precipitation which can allow us to quantify how much water is coming from precipitation versus other sources. The majority of research on urban streams has been done in temperate climates, leaving a gap in research on how urbanization chemically alters streams in semi-arid climates. This study focuses on understanding how urbanization modifies the hydrology and chemistry of streams in Reno, Nevada which has a semi-arid climate. We collected samples distributed longitudinally along an urban stream and a non-urban stream throughout the summer of 2022. We then measured and interpreted stable isotope signatures and the water chemistry of the samples. The results of this study will provide important information about the effects of urbanization on stream water quantity and quality in cities in semi-arid climates where water is a scarce, yet vital resource.

Recently, Great Salt Lake (GSL) has been at risk of complete desiccation, and as the lake water decreases, the salt concentration or salinity of the water increases. As a result, GSL’s shorelines are becoming exposed. In these shallow margins of the lake, sunlight can penetrate and power the ecosystem’s primary production. An important component is the microbial mats made by cyanobacteria which precipitate microbialites, organo-sedimentary dome-like structures made of calcium carbonate. Microbialites are key to GSL’s ecosystem as they are foundational contributors to the food web. Brine fly larvae graze on them, as do brine shrimp, and these invertebrates feed ten million migrating birds. The microbial communities of these structures are complex and may help maintain the structural integrity of microbialites. Predominantly found in this microbial community is a key cyanobacterium from the genus Euhalothece, a primary producer responsible for an estimated one-third of the lake’s photosynthesis. With the shrinking of GSL, continued desiccation and exposure coupled with restrictive salinities are likely to cause serious impacts on microbialites. The GSL Euhalothece species has not yet been isolated and characterized. We have developed cultivation methods to isolate this important cyanobacterium and have plans to sequence its genome. We can then search for genetic capacities for resiliency. This research will develop an assay for microbialite recovery following drought conditions and study Euhalothece sp.’s tolerance under several conditions of environmental stress.