EOS Volcanology Logo EOS Volcanology Slide Set #1
Plumes, Thermal Studies, and Mapping
PLUMES

SLIDE #1 (111K)
Space Shuttle photograph of the Mt. Spurr, Alaska, eruption plume. This view is a good match to the one obtained from TOMS data (Slide #2) on August 20, 1992. The brownish streak on the right half of the image is the volcanic cloud. Space Shuttle image # STS47-151-645, supplied by Cindy Evans, Lockheed Corporation.


SLIDE #2 (114K)
The Total Ozone Mapping Spectrometer (TOMS) on Nimbus 7 recorded the dispersal of the Mt. Spurr plume by mapping the sulfur dioxide released by the eruption. This image shows the plume the day after an eruption on August 19, 1992. Image supplied by Gregg Bluth and Arlin Krueger, NASA Goddard Space Flight Center.


SLIDE #3 (117K)
Daily TOMS observations have been used to study the dispersal of the Mt. Spurr plume. This has practical benefits, because as the plume went across the Midwest, air traffic controllers had to divert many planes going to Chicago over concerns about aircraft engines ingesting the fine ash. This slide shows the daily location of the plume between September 17 and 21, 1992. Image supplied by Gregg Bluth and Arlin Krueger, NASA Goddard Space Flight Center.


SLIDE #4 (73K)
One of the few opportunities to calibrate TOMS observations of sulfur dioxide arose when the Mt. Spurr cloud crossed over Toronto on September 19, 1992. A Brewer spectrometer was looking up at the plume, thereby allowing both the Nimbus 7 and Meteor 3 TOMS instruments to be directly compared with ground observations. Image supplied by Gregg Bluth and Arlin Krueger, NASA Goddard Space Flight Center.


SLIDE #5 (174K)
The dispersal of an eruption plume can also be studied using Advanced Very High Resolution Radiometer (AVHRR) images. Here we see the December 18, 1989, plume of Redoubt volcano, Alaska. The inset at the bottom shows that several distinct portions of the plume can be identified using standard image processing techniques, thereby enabling the change in plume structure (which may be the result of the loss of lithics, or changing aerosol composition) as a function of distance from the vent. Image prepared by Harold Garbeil, University of Hawaii.


THERMAL STUDIES

SLIDE #6 (168K)
The thermal channels of Landsats 4 and 5 can be used to identify areas of active lava flows, and to compare the extent of surface activity on a volcano on different days. Here we see two Landsat Thematic Mapper scenes of Kilauea Volcano, Hawaii. Bands 7, 5 and 3 are shown as red, green and blue. The data were obtained in July and October, 1991. Lava tubes have produced the strong thermal anomaly visible in the July scene. The pattern of hot spots towards the bottom right of the October scene shows that there were active pahoehoe flows at the time of data acquisition. Width of each image is about 15 km. Image prepared by Peter Mouginis-Mark, University of Hawaii.


SLIDE #7 (284K)
Under support from the NASA Geology Program, the University of Hawaii group often visits Kilauea volcano, Hawaii, to monitor the eruptions. Here we see a spectroradiometer being used to measure the temperature of an active lava flow in February, 1992. Photo by Henning Haack, University of Hawaii.


SLIDE #8 (99K)
The spectroradiometer shown in Slide #7 can measure the blackbody curve of a lava flow as a function of time. This lets us compute a cooling rate for the flow (see also Slide #9). Here we see three spectra that were obtained over a period of almost an hour at night (so that there is no solar contamination) on the February 19, 1992, lava flow field. Not only does the total energy (area under the curve) decrease as a function of time, but also the peak in the blackbody curve moves to longer wavelengths, indicating that the flow was cooling.


SLIDE #9 (90K)
The rate of cooling of a pahoehoe lava flow was determined from the data presented in Slide #8. Here we can see the progressive cooling of the surface over a time period of almost an hour. Also shown is the percent area of the hot radiating surface within the field of view (about 2 square meters) of the detector. Notice the small increase in temperature at about 20 minutes; we interpret this to be the result of a small intrusion into the flow field. Data from Flynn and Mouginis-Mark (1992).


MAPPING

SLIDE #10 (135K)
The May 18, 1980, eruption of Mount St. Helens, Washington, brought the hazards of volcanic eruptions to the attention of the general public in the United States. More than a decade after the eruption, space shuttle astronauts were able to obtain this view of the devastation that still surrounds the volcano. Space Shuttle image # STS47-73-056, supplied by Cindy Evans, Lockheed Corporation.


SLIDE #11 (137K)
Ground photographs of the devastation at Mount St. Helens show the extent to which the forests were destroyed by the debris avalanche and blast deposits. This photo was taken in July 1985 by Pete Mouginis-Mark, University of Hawaii.


SLIDE #12 (129K)
Spirit Lake was almost totally filled by fallen trees and mud from the May 18, 1980, eruption of Mount St. Helens. Over five years after the eruption, half of the lake was still clogged by the debris. Photo by Pete Mouginis-Mark, University of Hawaii.


SLIDE #13 (138K)
The Galapagos Islands have seven active volcanoes comparable to those found in Hawaii. In order to learn more about the structure and evolution of these volcanoes, the Hawaii group is conducting several remote sensing studies using Landsat, SPOT, TOPSAR, and SIR-C/X-SAR. Here we see a Landsat TM image of northern Isabela and Fernandina Islands. Image by Scott Rowland, University of Hawaii.


SLIDE #14 (141K)
A field expedition to Fernandina Island, Galapagos, was made by the Hawaii group in 1989, through funding provided by NASA's Geology Program. Here we see a field-equivalent of the Landsat TM (bands 1 to 4) being used on the 1968 phreatic deposit close to the summit of the volcano. Photo by Pete Mouginis-Mark, University of Hawaii.


SLIDE #15 (102K)
In 1968, the biggest observed caldera collapse took place on Fernandina volcano, Galapagos. When we visited the volcano in 1989, the walls of the caldera were more than 1,100 meters high, permitting an outstanding view of the lava flows that comprise the inner wall. On the caldera floor, the black lava flows erupted in 1988 can also be seen. Photo by Pete Mouginis-Mark, University of Hawaii.



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