The mysterious geologic forces behind the current eruptions of Mt. Kilauea are quietly creating the newest piece of America. Climbing 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 as the ninth Hawaiian island. "Loihi has grown about 10,100 feet from the Pacific floor," Thomas L. Wright, scientist-in-charge of the Hawaiian Volcano Observatory, said. "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." The observatory, on the rim of Kilauea's summit caldera, or lava lake, is operated by the U.S. Geological Survey. Volcanoes have been creating and modifying the environment over eons of geologic time. More than 80% of Earth's surface is of volcanic origin. Volcanic eruptions have formed fertile soils and sculpted mountains, plateaus and other majestic landscapes. Gaseous emissions from volcanic vents helped to form the early atmosphere and oceans where scientists believe life first emerged. The volcanic machine powering Kilauea and building Loihi may represent the most visible and most persistent example of this little-known facet of volcanoes. Kilauea has been in the news time and again since it resumed erupting on Jan. 3, 1983. Lava oozing at the rate of 635,000 cubic feet each day has traveled 20 miles east to the Pacific Ocean. Lava flowing from the eruption, 50 feet thick in some places, already has torched 140 houses and caused more than $60 million in damage. Last May 5, a 2,000-foot-wide flow cut off an entire village on the island's southeast coast, and Gov. John D. Waihee declared the town a disaster area. These highly publicized lava flows, and 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 fit together like pieces of a jigsaw puzzle to make up the planet's surface. There are about a dozen of these plates, each of which is about 50 miles thick. The plates move relative to each other a few inches a year. Active volcanoes tend to occur in zones of under-thrusting, or "subduction," where one plate is slipping beneath another. 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 fractures to spill onto the surface or ocean floor. Over about 70 million years, the continuous movement of the Pacific plate over this stationary "fountain of fire" left a trail of more than 80 big volcanoes over the floor of the Pacific Ocean. Called the Hawaiian Ridge-Emperor Seamount Chain, the islands and undersea mountains, or seamounts, stretch northwestward about 4,000 miles, from the Big Island of Hawaii to the Kamchatka Peninsula in Soviet territory. The five main Hawaiian islands are the tops of volcanic mountains that were formed as the Pacific plate moved over the Hawaiian hot spot. A scientific record of the plate's movement to the northwest is evident in the age of solidified lava left on each of the islands. The age decreases from northwest to southeast. Kauai, in the extreme northwest, is 5.6 million years old; Oahu is 3.4 million; Molokai is 1.8 million, Maui is 800,000, Hawaii is under 700,000 years old. Lava ages even decrease in the same northwest-to-southeast fashion on each individual island. Continued movement of the Pacific plate promises to give the goddess 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 not know exactly when Loihi will emerge as a new island. Assuming Loihi's growth continues at current rates, it could take 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 cease 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.
An undersea mountain named Loihi, SE of the Big Island of Hawaii, has grown 10,100 feet from the Pacific floor and needs 3,100 more feet to emerge as the ninth Hawaiian island. The five main islands are tops of volcanic mountains, formed when the Pacific Plate moved over the "Hawaiian hot spot". Their ages are: Kauai, 5.6 million years; Oahu, 3.4 million years; Molokai, 1.8 million years; Maui, 800,000 years. Hawaii is under 700,000. Its two active volcanoes are Kilauea and Mauna Loa. In a recent paper, Dr John Fasullo, an oceanographer at Columbia University, New York, said that if sea levels rise by 1 metre in this century, it would be enough to cause flooding on all