Remote sensing techniques are being used increasingly to address volcanological problems. This thesis is concerned with the interpretation of multispectral infrared data of volcanic thermal features. Data from the two short wavelength infrared (SWIR) bands of the Landsat Thematic Mapper (TM) are used to constrain sizes and temperatures of subpixel resolution hot spots. Analysis of a 1989 TM scene of Lonquimay volcano suggests a cooling from 250 to 170°C of the crust of an active lava flow down 1.5 km of its length. Estimates of the summed radiative and convective heat losses from the flow top fall from 6 to 3 MW per 30 x 30 m pixel downflow. Thermal data were collected at volcanoes in Chile, Nicaragua and Italy to test assumptions explicit in such calculations. These surveys suggest that SWIR emission from fumarole fields is dominated by that from the interior walls of vents, and that surface temperatures around fumarole vents are lower than those of typical active lava bodies. The relative response of the two SWIR sensors of the TM is sensitive to such differences and therefore provides a basis for the interpretation of thennal anomalies known only from satellite data. Comparison of measurements in the two SWIR bands is petfonned with fourteen TM scenes recorded between 1984 and 1991, of a persistent hot spot at Lascar volcano, Chile. Evolution of the thennal source is charted by comparing the summed spectral radiance in each of the SWIR bands. Thus it appears that Lascar has experienced at least two periods of lava dome growth punctuated by the explosive eruptions of 1986 and 1990. Infrared sensors to be deployed on forthcoming remote sensing platfonns, including the Japanese Earth Resources Satellite and NASA's Earth Observing System, promise to constrain thennal emissions from volcanoes more effectively than possible with existing orbital systems. These investigations will improve understanding of the physical processes that influence the emplacement of lavas, as well as the potential for detecting eruption precursors and evaluating volcanic hazards.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:293718 |
| Date | January 1991 |
| Creators | Oppenheimer, Clive |
| Publisher | Open University |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://oro.open.ac.uk/57337/ |
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