Water Resources Research Act Program

Details for Project ID 2020HI314B

Integrating Geological, Geophysical, Remote Sensing, and Groundwater Data into a Geothermal Resource Assessment for American Samoa

Institute: Hawaii
Year Established: 2020 Start Date: 2020-03-01 End Date: 2021-02-28
Total Federal Funds: $34,740 Total Non-Federal Funds: $62,091

Principal Investigators: Nicole Lautze

Abstract: The American Samoa Power Authority (ASPA), American Samoa Renewable Energy Committee (ASREC) and American Samoa Environmental Protection Agency (ASEPA) are investigating ways to improve the sustainability of American Samoa’s water resources and electricity infrastructure. Local renewable energy options in American Samoa can reduce American Samoa’s dependence on imported fossil fuels, can economically benefit an island with some of the highest electricity costs in the nation, and will reduce carbon emissions (Ness et al., 2016). Recent studies that have identified the cause of volcanism on American Samoa ca. 600 years ago also suggest a likelihood that exploitable geothermal resources exist on Samoa. From 2013 to 2016, Geologica Geothermal Group, Inc., was contracted by ASPA to provide a geothermal resource assessment. The results included an impressive framework of data now publicly available and two ~2,000-foot-deep groundwater wells that are valuable for scientific applications and resource management, which are currently sitting unused. We believe that revisiting and building upon the previous resource assessment, in the context of our experience with geothermal on Hawai‘i, may provide important new insight into American Samoa’s geothermal resource potential. Based on previous research with Hawaiian hydrothermal systems, the Hawai‘i Groundwater and Geothermal Resources Center (HGGRC) will conduct a high-level assessment of data currently available in American Samoa to assess the potential for subsurface permeability, fluid and heat; the three qualities necessary for a geothermal resource to exist. We expect these data will include regional and local seismic data, territory-wide InSAR data, groundwater data, review of current geologic maps and possibly new geologic mapping, with particular attention on the two deep boreholes. Anticipated outcomes include both a supplementary geothermal assessment to ASREC and recommendations for how to best manage the holes. These holes provide value to ASPA and ASEPA, whether that be for groundwater monitoring, monitoring of volcanic activity, or potential deepening for geothermal exploration. Four key methods will be utilized to compile and analyze existing data: (1) review of existing groundwater with sampling at priority sites, (2) assessment of existing seismic data products for indications of geothermal activity, (3) InSAR analysis to detect and measure surface movements that may be indicative of geothermal activity, and (4) working directly with stakeholders to develop a utilization plan for realizing the scientific and resource management value of the deep groundwater boreholes. The Geologica report recognized both seismic and InSAR analysis as viable candidates for follow-up studies due to their nature as long-term monitoring techniques. ASPA can provide HGGRC with access to the recently collected but unpublished seismic data, and raw InSAR data is publicly available and will be processed by the graduate and undergraduate student researchers hired by this project. A preliminary gravity survey will be completed on Tutuila with an HGGRC-owned gravimeter.