Astronaut Photography - Observing Earth's Systems from Space
by Rebecca Dodge in collaboration with NASA scientists
Volcanic eruptions, another Dynamic Events target of Crew Earth Observations, produce aerosols that are distributed globally and are responsible for atmospheric cooling28, as well as for effects on cloud formation and rainfall. The images to the left29 show the Earth's limb at sunset, before and after the eruption of Mount Pinatubo in 1991. In the top picture thunderstorms flatten out at the tropopause, in a relatively clear atmosphere. In the lower picture taken two months following the eruption of Mt. Pinatubo, two distinct dark layers in the stratosphere indicate aerosols injected into the stratosphere by the eruption. Pinatubo's eruption had global effects, and will be monitored from the ISS along with other active volcanoes29.
Volcanic eruptions can have more local effects, including the disruption of air traffic created by ash clouds. Here again the unique perspective views available from the shuttle and the ISS enable scientists to see not only the horizontal extent of the eruption within the Atmosphere, but also the vertical extent. The ISS can platform passes over any give target two or more times daily, so that astronauts can photograph dynamic events many times and can coordinate with ground observers as well.
29. (http://eol.jsc.nasa.gov/EarthObservatory/Astronauts_Photograph_Mount_Pinatubo.htm Astronauts Photograph Mt. Pinatubo STS41D-32-14 August 30,1984 STS043-22-23 August 8, 1991)
During the 1994 eruption of the Klyuchevskaya volcano on the Kamchatka Peninsula of Russia (right), the eruption plume reached and altitude of 60000 feet (18300 meters), spreading ash as for as 640 miles (1030 km). International flight are concentrated in this the airspace, and eruptions form "ring of fire" volcanoes such as Klyuchevskaya can have potential to disrupt as many as 70 flights each day.
ISS astronauts have been the first to observe remote eruptions, alerting scientists to renewed volcanic eruption on Anatahan Island30. The island, part of the Northern Mariana Island Chain, had been evacuated in 1990 because of strong earthquake activity. Astronauts observed the first recorded eruption of Anatahan volcano on May 11, 2003, prior to its detection by volcano monitoring networks. The seismic activity and ashfall related to this eruption caused the declaration of a state of emergency in the Northern Marianis Islands.
30. (http://eol.jsc.nasa.gov/EarthObservatory/FirstRecordedEruptionofAnatahanVolcano.htm First Recorded Eruption of Anatahan Volcano)
While the impacts of ash plumes and lava flows may be profound, pyroclastic flows31 (fast-moving, hot mixtures of shattered lava fragments, volcanic gas, and air generated during explosive eruptions) and mudflows32 (slurries of volcanic rock, ash and water, liquefied by heavy rains) are often the real killers during and after volcanic eruptions. Crew Earth Observations will monitor volcanoes with known propensity for such events, including Pinatubo29 and the Santa Maria Volcano in Guatemala33 (left).
The Santa Maria volcano's 1902 eruption created a large crater on the mountain's southwest flank, during one of the 20th century's largest eruptions. The crater began filling with a lava dome, Santiaguito, in 1922. Pyroclastic flows that accompany dome growth have occurred as recently as 2001. Volcanic debris ejected from the growing dome is a continuing source for mudflows that flood south-flowing streams. The 1929 collapse of this dome killed over 5000 people; new crater formation on the northern flank of the volcano would threaten the town of Quezaltenango, home to almost 100,000 people.
31. (http://earthobservatory.nasa.gov/Study/Lahars/ When Rivers of Rock Flow)
32. (http://earthobservatory.nasa.gov/Study/Domes/ Domes of Destruction)
33. (http://eol.jsc.nasa.gov/EarthObservatory/Santa_Maria_Volcano,_Guatemala.htm Santa Maria Volcano, Guatemala)
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