Geology And Geophysics

Life near an Active Volcano under the Volcano Life in Hawaii Lava from Magma Hot Volcanoes



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"Life near an Active Volcano under the Volcano Life in Hawaii Lava from Magma Hot Volcanoes"
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Living on an active volcano is about as serene as anyone could imagine.  That is because, Hualalai, the volcano upon which I sit as I type, has been relatively quiet for decades.

However, on the other side of our island of Hawaii, Kilauea is not so serene.  Nor is it threatening, either.  Although belching fire and brimstone for almost thirty years now, one intrepid enough to brave the jungle and heat, can approach the 2,500  degree Fahrenheit molten lava and, upon a twig, toast a marshmallow over it.  Kilauea, like all Hawaiian hot spot volcanoes, is a shield volcano.  Moving a few meters per hour, only the forest cannot outrun lava here.  Yes, they consume everything in their path, including homes, but it must be remembered it is the volcanoes that gave us this land, and while the death part is momentary and destructive, the life-maintaining portion lasts many human generations in geologic time.

Having been in both locations, I have to admit that living in the Pacific Northwest, as a child, Mt. St. Helens, a composite volcano, (as are all the Cascade Mountains), was much more entertaining, and explosive.  Composite volcanoes, also known as stratovolvanoes, and sometimes andesitic volcanoes, are the more unpredictable ones.  They have the classic mountain shape with steep sides and often near perfect pointed cones.  Mt. St. Helens was almost Fuji like on May 17, 1980, but the next morning, Ka-boom. My sister in Spokane got to see St. Helen’s several hours after the rest of us, because it came (the top part of it) to her in a shower of ash.

Why do some volcanoes blow in massive bursts, and others, as though living in slow, paradise, island time, slowly flow out their glowing rivers?  It would be great to say that this is just the way we do things in the islands, slow and leisurely.  The real reason is because of the composition, pressurized gases and water, and mass of the mountains.  Mt. St. Helen’s, and most of the Cascade cones all along the west coast of the Pacific along the eastern side of the ring of fire, have much more pressure built up.  They are not casually flowing basalt, allowing it to puddle into ropy pahoehoe lava, the way we do things here on Hawaii, and also in Iceland.

Although they do let off some steam, Composite volcanoes usually always have a several thousand year old plug right in their central core which allows a lot of pressure to build up. Composed of andesite, a largely porphyritic rock base with many crystals, they are known for their explosive tempers, pyroclastic flows, lahars, and the occasional pyroclastic bomb, a boulder which may be as big as a house falling out of the blue. A lahar is a fast moving river of lava, rocks, snow, ice, water, and mud, (and often bits of forest blown off on the way) that will avalanche off the sides of a composite volcano eruption.  It is the content of super heated water and gases that make these giants so explosive. By the way, the Andes are Andesite volcanoes, and appropriately named for this reason.

It was wonderful living among the gorgeous Cascade volcanoes, and visiting there will always be a top priority, but there is something to be said for the slow and lazy island ways of our Pele (volcano goddess of Hawaii) productions with their beautiful sparks and night glow of magma as it erupts from the depths.  Like Pele’s legendary incandescent eyes, and red Ohia flower-like showers when the rare “curtain” of fire erupts from the crater, the fiery show is memorable.  But on a daily basis, even now, the inside of our earth is melted to liquid glassy basalts, and slowly makes its way to the Pacific. Once there, the hisses of new earth whispers of the Hawaiian black lava beaches and their swaying palms to come. In just a few hundred years or so, the beach resort may be ready for your reservation.  Until then, be prepared to bring a telescopic lens if you visit. 

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More about this author: Christyl Rivers

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