DUCKS: A continuous thermal presence on the rim of Pu'u 'O'o

For the past 2 years we have been monitoring the persistent activity at the Pu'u 'O'o crater (Kilauea, Hawaii) with a permanent system of infrared thermometers. Our intent has been to implement a cheap, robust, modular real-time thermal system capable of surviving the harshest of conditions. The system cost \10,000 to construct and consists of three modules: field-based sensors, a repeater station and a reception site. The field-based component consists of three thermal infrared thermometers, housed in pelican cases with selenium-germanium-arsenic windows. Two 1 degree field of view (FOV) instruments allow specific but small areas to be monitored, and a 60 degree FOV provides an overview for all crater floor activity. A hard wire connection extends 25 m to a pelican-case-housed microprocessor, modem, and power module. From here, data are transmitted using Yagi antennas, via the repeater site, to a dedicated PC in the lobby of the Hawaiian Volcano Observatory. Here, the three channels of data are displayed on-screen, with a delay of ~3 seconds between data acquisition and display. Data are also used to automatically update web-based plots for general access. Aside from some minor glitches, such has sensor damage during probable tampering and unresolved data stream failures, the system has been in continuous operation since March 2001. In this regard, careful waterproofing of connectors, cables and protective cases has kept out the extremely wet and acidic atmosphere encountered at the crater edge. We have also constructed self-contained versions with internal loggers for \1500/unit. These have been deployed in a temporary fashion at Stromboli, Masaya and Erta Ale. Together these instruments have proved capable of detecting thermal signals associated with (1) gas puffing and jetting, (2) spattering, (3) lava effusion, (4) crater floor collapse, (5) vent blockage-and-clearing, and (6) lava lake overturn.