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Preliminary Results of a Magnetotelluric (MT) Survey Across and Core-Hole Drilling Into East Maui Volcano (Hawaiʻi, USA)
Mattox TELWAR, Nicole LAUTZE, Amir HAROON, Erin WALLIN, Eric HASKINS
[University of Hawaii Manoa, USA]
The Ghyben-Herzberg relation is considered the standard model for groundwater hydrology in ocean-island environments. This model is based on simplified assumptions but is still used to provide a basic level of groundwater storage in Hawaiʻi. Over the last 25 years, each and every scientific drilling project on Hawaiʻi Island has revealed complex hydrology, which the standard model does not explain. Scientists encountered surprisingly deep freshwater, warm water, and perched freshwater under a variety of groundwater regimes and hydrostatic pressures. It is hypothesized that Hawaiʻi’s groundwater and geothermal systems are complex, and that more surveying is required to understand the storage of freshwater and prospective geothermal resources across all islands as they age. This study aims to investigate the unique hydrology and prospective resources on the southwest rift zone of East Maui Volcano, more commonly known as Haleakalā. Our survey is located along the southwest rift zone of East Maui Volcano, which is a critically understudied leeward region of East Maui. A large portion of this rift zone is privately owned and classified for agricultural use. East Maui Volcano’s current volcanic state provides an opportunity to examine the distribution and transport of groundwater and residual magmatic heat from more permeable shield-stage aquifers to post shield-stage structures. We conducted a magnetotelluric (MT) survey of 59 stations on and around the rift zone. The resistivity data is inverted to 1D and 3D models to confirm the elevation of the water table and understand the system that is driving groundwater storage. We also have commenced drilling of a cored borehole to confirm and compare the findings from the electromagnetic survey. Drilling to date has been challenging. The goal of this project is to provide an accurate depiction of the extent, source, and temperature of groundwater along an understudied region of Maui. This paper introduces and provides a project status update.
Topic: Geophysics