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Prehistoric Human Response to Climate Change 2010

Hey Claude, I don't know much about volcanoes, I was wondering more about how the volcanoes near you differ from the ones in my backyard here in Oregon. Is it the same kind of ash? and what makes the layers have different colors of ash, does each volcano give out a distinctive color, or can one volcano in different stages of its life give out new colors? or both? and you have terrific photos of everyone, thanks for a great journal. Michael Lampert

Wed, 07/21/2010 - 02:32

Claude Larson

Hi Michael,I have Jodi Bourgeois here to help answer your questions. The setting
that makes volcanoes in each place is the same. Both Oregon and
Kamchatka volcanoes form due to a subduction zone. This is where one
tectonic plate slides under another tectonic plate. However, the
volcanoes here are more active than those by you. Most of the ash is
similar because ash comes from explosive eruptions. These eruptions
tend to have a lot of silica in them. Kamchatka does have some
volcanoes that more basaltic, such as Kliuchevskoi, but that one is not
explosive due to lower silica content. It does have lava flows and lava
fountains. The different colors of ash are due to two basic things,
mineral composition and weathering. If there is a lot of silica the ash
will be white, if there is a lot of iron in the ash it will turn orange
like some of the layers of ash here. Volcanoes can give out different
kinds of ash at different times in its history. There are different
chambers under the volcano and each chamber can have a different type of
magma. Each magma, when it would erupt would then be a different
color. Shiveluch ash tends to be salt and pepper grey, but then there
was an eruption of Shiveluch that caused an orange layer, that eruption
was named Dvnoinoi. Hope these answers are helpful. Thanks for joining
our expedition.
Claude