A core hole in the southwestern moat of the Long Valley Caldera: Early results



A continuously cored hole penetrated 715 m into the southwestern moat of the Long Valley caldera. Temperatures in the postcaldera deposits increased rapidly with depth over the upper 335 m to 202°C, then remained nearly isothermal into the Bishop Tuff to the bottom of the hole. The depth to the Bishop Tuff is the shallowest, and the temperatures observed are among the highest in holes drilled in the caldera. The hole identifies a potential geothermal resource for the community of Mammoth Lakes, constrains the position of the principal heat source for the caldera's hydrothermal system, and serves as access for monitoring changes in water level, temperatures, and fluid chemistry.