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Michael S. Ramsey

Publications and source records attributed to Michael S. Ramsey.

3 recordsLinked to original sources

Operational thermal remote sensing and lava flow monitoring at the Hawaiian Volcano Observatory

Hawaiian volcanoes are highly accessible and well monitored by ground instruments. Nevertheless, observational gaps remain and thermal satellite imagery has proven useful in Hawai‘i for providing synoptic views of activity during intervals between field visits. Here we describe the beginning of a thermal remote sensing programme at the US Geological Survey Hawaiian Volcano Observatory (HVO). Whereas expensive receiving stations have been traditionally required to achieve rapid downloading of satellite data, we exploit free, low-latency data sources on the internet for timely access to GOES, MODIS, ASTER and EO-1 ALI imagery. Automated scripts at the observatory download these data and provide a basic display of the images. Satellite data have been extremely useful for monitoring the ongoing lava flow activity on Kīlauea's East Rift Zone at Pu‘u ‘Ō‘ō over the past few years. A recent lava flow, named Kahauale‘a 2, was upslope from residential subdivisions for over a year. Satellite data helped track the slow advance of the flow and contributed to hazard assessments. Ongoing improvement to thermal remote sensing at HVO incorporates automated hotspot detection, effusion rate estimation and lava flow forecasting, as has been done in Italy. These improvements should be useful for monitoring future activity on Mauna Loa.

Hawaii

High-resolution satellite and airborne thermal infrared imaging of the 2006 eruption of Augustine Volcano: Chapter 22 in The 2006 eruption of Augustine Volcano, Alaska

Thermal infrared (TIR) images provided a timely pre- and syn-eruption record of summit changes, lava flow emplacement, and pyroclastic-flow-deposit distribution during the Alaska Volcano Observatory's (AVO) response to the 2006 eruption of Augustine Volcano. A series of images from both handheld and helicopter mounted forward looking infrared radiometers (FLIR) captured detailed views during a series of 13 overflights from December 2005 through August 2006. In conjunction with these images, data from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) provided frequent multispectral synoptic views of the eruption's emissions and deposits. The ASTER Urgent Request Protocol system also facilitated more frequent scheduling and faster data availability during the eruption. Airborne and satellite imaging provided 20 different days of TIR coverage over the 5-month eruptive period, with 4 of those days covered by both FLIR and ASTER. The high-resolution TIR images documented gradual pre-eruption heating of the summit, emplacement of pyroclastic-flow deposits, rapid temperature increase as the lava dome and flows formed, and slow cooling of the volcanic deposits that followed. The high-resolution data uniquely documented segmentation of the lava flows into hot areas of increased flow deformation and cooler, more stable crust on the active flows. In contrast, the satellite TIR data provided synoptic views of the areal distribution of volcanic products at Augustine including the extent and composition of the plumes.

Alaska

Use of thermal infrared imaging for monitoring renewed dome growth at Mount St. Helens, 2004

A helicopter-mounted thermal imaging radiometer documented the explosive vent-clearing and effusive phases of the eruption of Mount St. Helens in 2004. A gyrostabilized gimbal controlled by a crew member housed the radiometer and an optical video camera attached to the nose of the helicopter. Since October 1, 2004, the system has provided thermal and video observations of dome growth. Flights conducted as frequently as twice daily during the initial month of the eruption monitored rapid changes in the crater and 1980-86 lava dome. Thermal monitoring decreased to several times per week once dome extrusion began. The thermal imaging system provided unique observations, including timely recognition that the early explosive phase was phreatic, location of structures controlling thermal emissions and active faults, detection of increased heat flow prior to the extrusion of lava, and recognition of new lava extrusion. The first spines, 1 and 2, were hotter when they emerged (maximum temperature 700-730°C) than subsequent spines insulated by as much as several meters of fault gouge. Temperature of gouge-covered spines was about 200°C where they emerged from the vent, and it decreased rapidly with distance from the vent. The hottest parts of these spines were as high as 500-730°C in fractured and broken-up regions. Such temperature variation needs to be accounted for in the retrieval of eruption parameters using satellite-based techniques, as such features are smaller than pixels in satellite images.

Washington