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Show Thursday, November 22, By National Geographic For AP Newsf eatures VOLCANO, Hawaii The mysterious geologic forces powering the current eruptions of Hawaii's are quietly creating Mount Kilauea the newest piece of American territory. Combing with agonizing slowness from the warm tropical waters just southeast of the Big Island of Hawaii is an undersea mountain named Loihi. Volcanologists believe Loihi eventually could emerge above the surface as the ninth Hawaiian island. "Loihi has grown about 10,100 feet from the Pacific Boor," Thomas L Wright, sdentist-in-charg- e of the Hawaiian Volcano Observatory, told National Geographic. "It seems to be tapping the same source of magma (lava still underground) as Kilauea. Loihi needs about 3,100 more feet to break the surface." Perched on the very rim of summit caldera, or lava a's lake, the observatory is operated by the JS. Geological Survey. Volcanoes have been creating and modifying the Earth's environment over eons of geologic time. More than 80 percent of the Earth's surface is of volcanic origin. Volcanic eruptions have formed fertile soils, sculpted mountains, plateaus and other majestic landscapes. Gaseous emissions from volcanic vents even helped form the early atmosphere and oceans- - Yet, the volcanic machine powering Kilauea and building Loihi may rank as the most visible and most n persistent example of this facet of volcanoes. For Kilauea has been in the news time and again since its current eruption began Jan. 3, 1963. Lava oozing at the rate of 635,000 cubic feet each day has spread 20 miles east to the Pacific Ocean. Lava flows from the eruption, 50 feet thick in some places, already : little-know- have destroyed 140 homes and caused more than $60 million in damage. Last May 5, a flow cut off an entire village on the island's southeast coast, forcing Gov. John D. Waihee to declare the town a disaster area. 2,000-foot-wi- de These highly publicized lava flows, atid those silently lifting Loihi toward the surface, result from the peculiar form of volcanic activity occurring in Hawaii. Most of the 500 active surface volcanoes on Earth straddle the margins of continents and the huge plates of rock that are fitted together like pieces of a jigsaw puzzle to make up the planet's surface. Earth's surface consists of about a dozen of these plates, each of which is about 50 miles thick. The plates move relative to each other few inches a year. Active volcanoes tend to occur in zones of underthrusting or "subduction," where anothw one plate slides beneath Page All new property This undlereeav! . THE HERALD, Provo, Utah, 1990 But how can volcanic activity occur in the Hawaiian Islands, which are more than 2,000 miles from the nearest plate margin? Hawaiian volcanoes are believed to result from a different phenomenon termed "hot spot" volcanism. Geologists .theorize that deep under the Pacific plate is an exquisitely hot, stationary region termed the "Hawaiian hot spot" Like a propane torch placed under a moving sheet of plastic, the hot spot melts rock in the overriding Pacific plate. The molten rock, or magma, is less dense than surrounding solid rock and rises through fracture zones to spill onto the surface or ocean floor. Over a span of about 70 million years, the continuous movement of the Pacific plate over this stationary "fountain of fire" sputtered a trail of more than 80 big volcanoes over the floor of the Pacific Ocean. Called the Hawaiian Ridge-EmperSeamount Chain, the islands and undersea mountains, or seamounts, stretch northwest about 4,000 miles, from the Big Island of Hawaii to the Kamchatka Peninsula in the Soviet Union. or The five main Hawaiian islands are the tops of volcanic mountains formed as the Pacific plate moved over the Hawaiian hot spot. A scientific record of the plate's movement to the northwest is written in the age of solidified lava left on each of the islands. The age decreases from northwest to south east Kauai in the extreme northwest is 5.1 million years old; Oahu, 3.4 million; Molokai, 1.8 million; Maui, 800,000; Hawaii, less than 700,000. Lava ages even decrease in the same northwest-to-southea- st fashion on each individual island. Continued movement of the Pacific plate promises to give Pele a new home, and . Hawaii a new island. . If theories about hot spot volcanism are correct plate movement eventually will carry the Big Island off the Hawaiian hot spot The two active volcanoes on the island, Kilauea and Mauna Loa, will become extinct. The hot spot then will pour molten rock onto the surface through the next volcano in the Hawaiian chain. Experts do net know exactly when Loihi will break the surface and emerge as a new island. As- suming Loihi's growth continues at current rates, it could take anywhere from a few thousand to a few tens of thousands of years. But other fates also may await the infant volcano. Infusions of molten rock from the hot spot for instance, may halt unexpectedly. Loihi's growth would be stunted, leaving it just another seamount in the chain. The ninth Hawaiian island thus may form in an entirely different place. There is also the possibility a sudden major undersea eruption could raise Loihi to the surface sooner than anyone expects. u$wS ft National Geographic SocietyRobert , y-- -- - V ' .... - j - v. r L National Geographic SocietyRobert W. Madden , PAR 1B. v irrTSsrsy a a i i V Balance in ii stir' lr TfUlR Parka Mens &. Ladies. Waterproof I Reg. $ riASK i ' q I 1 $100 REBMEm LASER PRINTERS $1249 I AS -- AffrReb. in the Plum Tree Plaza in Provo Located Between ShopKo and Food-4-Le- ss OPEN 10AM to 6PM, Mon thru Sat JIA (5 vj. Mfl W m ax (801)377-655- ; 5. afc aw rnmrni uj ATD - i t i Unffffu ffl : Basketball Shoe Black Only h Reg. $80 "V u m m j kv if I YlkDi nt. 1 : 1200 Ski Packag I III! r RACKS x OF CLOTHING 1 "A SKI GLOVES 1 llP J ' 1 K ' S WINTER rVl I Jl M Tarm : J I (YOUR COMPUTER MANIAC Small craters pit cinder cones within a much larger crater atop Haleakala, a dormant volcano in HawaiL Scientists believe volcanoes in this chain resulted from a "hot spot," far below the Earth's crust m W. Madden Molten rock sprays from Hawaii's Mount Kilauea, one of the Earth's most active volcanoes. Bindings Poles a v i l i , ii QT4TPTQ Bart Simpson, Side Out yuarript, New Balance . |