RAPID: Monitoring hydrochemical effects of the 6.5 Monte Cristo Range Earthquake on groundwater systems in the Columbus Salt Marsh (central NV) and vicinity

Board Of Regents, Nshe, Obo University Of Nevada, Reno, Reno NV

Investigators

Abstract

Earthquakes can have both immediate and long-term effects on wells and springs fed by groundwater, including changes to water quality and flow rate. Chemical properties, measured as water quality parameters, are influenced by where the waters originate, and by how it interacts with rocks and minerals in the aquifer. In the arid west, many rural communities depend on groundwater exclusively, and it is important to understand potential threats to groundwater quality and spring flow that earthquakes may pose. In Nevada, a 6.5 magnitude earthquake occurred on May 15th, 2020 near Tonopah, a rural part of state known to have active faults with recurrent earthquakes. This event is the largest to have occurred in Nevada in over 60 years and was felt across more than 120,000 square miles with roughly 7000 aftershocks. The research team will continue a preliminary sampling campaign to determine water quality and water flow rate from wells and springs close to the epicenter. The team will continue to monitor and sample these sites over the next year to look for any temporary or more lasting earthquake-related effects to flow and water quality. This study will provide valuable information to understand how earthquakes affects groundwater in desert regions, especially when reconnecting water supplies, and understanding what the health risks may be of using undamaged wells after major earthquakes. This project will also train one student in field sampling and laboratory chemical analysis. This project seeks to determine the hydrochemical effects of the May 15, 2020 Mw 6.5 Monte Cristo Earthquake (NV) on groundwater resources within a 30km of the epicenter. A year-long monitoring program will be used to assess the seismic response and decay of that signal over time, focusing on changes in elemental and stable isotope chemistry, and flow rate of artesian wells. This earthquake provides a great opportunity to investigate the linkages between crustal processes and groundwater systems across distinct hydrographic basins in an active seismic zone, the Walker Lane, along the eastern side of the Sierra Nevada mountains. This study is important for community water supplies after earthquakes and has not been done in Nevada before. Much of rural Nevada relies on groundwater, including residential private wells and municipal wells. The monitoring program has engaged community members and increased local awareness of seismic hazards affecting well water and will continue to involve community members and train university students in the sampling effort. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.