Monitoring and Studying Volcanoes - 11 of 10

Monitoring and Studying Volcanoes FAQs - 10 Found

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Lava sampling: Why do we do it?

Hot lava samples provide important information about what's going on in a volcano's magma chambers.

We know from laboratory experiments that the more magnesium there is in magma, the hotter it is. Chemical analysis, therefore, provides the means not only to determine the crystallization history of lava but also to establish the temperature at which it was erupted.

For example, Kilauea's Episode 54 lavas (erupted January 30, 1997) are chemically different from lavas erupted from 1985 to 1997. Chemical analyses show that magma was supplied by two distinct magma bodies that have resided for years beneath Napau Crater, where eruptions last occurred in 1983 and in 1968. Lava nearest Pu'u O'o erupted at 1,125 degrees Celsius to 1,130 degrees Celsius (2,057 to 2,066 degrees Fahrenheit) and contains crystals of olivine, feldspar and pyroxene. Calculations show the source of this lava was intruded at the beginning of the Pu'u O'o eruption in January 1983. The lava erupted from the west wall of Napau tapped a second magma body that was possibly emplaced in August 1968. This magma, which had been cooling and crystallizing for a longer time, erupted with more abundant feldspar and pyroxene crystals and at lower temperatures of 1,110 to 1,120 degrees Celsius (2,030 to 2,048 degrees Fahrenheit).

Hawaii Volcano Observatory, 1997: HVO Volcano Watch, March 14, 1997, U.S. Geological Survey Web page,, accessed Nov 16, 2012.
