With great diving weather, the ship has been abuzz with activity preparing for dives to the Central Caldera geophysical site. Last night, the medium power J-Box, MJ03F, was installed on Dive R7124, and a broadband seismometer and low-frequency hydrophone were deployed on Dive R1725. The final instrument at this site, a bottom pressure-tilt sensor has just been deployed on the seafloor on Dive R1726. ROPOS is now on its way to the surface. We will install the ~4.6 km extension cable during the night and into tomorrow, finishing installation at this site.
With each site complete (currently Eastern Caldera, International District 2, and by tomorrow Central Caldera), we now have our "eyes" on completing the International District 1 Site. This Site hosts an array of hydrothermal-focused instruments that include a mass spectrometer, digitial-still camera, and a fluid and microbial-DNA sampler for time series temperature, fluid chemistry, and genetic analyses. These instruments will be installed at the diffuse flow site called El Gordo, the fat one. It hosts several dense clusters of tubeworms, palm and scale worms, blue ciliates, and bacterial mats. A halo of diffuse flow rims the main high-temperature flow site marked by white bacterial mats that form in the cracks and crevices between the rugged basaltic bedrock.
We will also install two instruments that go into the throat of high-temperature orifices at the chimneys called Diva and Escargot. It is now very clear that the International District hydrothermal field has been heating up this past year: vent fluids at Escargot have risen 30-40°C since we measured temperatures at this site in July 2013. We are anxious to have real-time data to see if this increase in temperature is correlated with an increase in gases, less salty fluids emitted from the vents, and an increase in seismic activity — all of which may indicate "big things" to come…