Hawaii, the biggest and newest island in the State of Hawaii, is called “The Big Island.” Five shield volcanoes formed the island. Two are still active. Kilauea, currently the world’s longest continually-erupting volcano, has erupted steadily since 1983 and is expected to continue for another hundred years.
Maunakea, rising 14,000 feet above sea level, is dormant now. It is the only place in the Hawaiian Islands that has snow. Alie’s sister, Michelle, planned to visit the Keck Observatory at 13,796 feet, but black ice on the road and one hundred mile per hour winds prevented it. From its base on the sea floor to the top, Maunakea is over 37,000 feet tall, 4000 feet taller than Mount Everest.
Mauna Loa last erupted in 1984; its lava flow stopped four miles outside Hilo, the principal town on the island.
A volcano occurs where there is a ‘hot spot’ under the earth’s crust, a place where molten magma rises close to the surface. Generally the earth’s crust is thinnest under the sea floor. At any given time, there are about twenty-five hot spots under the ocean. One is under the Big Island. Indeed, a new Island is forming 2000 feet beneath the sea to Hawaii’s south.
A total of 136 Hawaiian Islands stretch 1200 miles from Hawaii to Midway. All were formed by volcanoes over this hot spot. The hot spot does not move; the islands do. They move north about four inches per year as the earth’s tetonic plates slide past each other.
While they move north, wind and water erode the mountains. With the exception of those still erupting, all were taller at one time. Kauai was formed about six million years ago; Maui, four million years ago.
Over those millennia, coral reefs form in the shallow waters around the mountain. In the most extreme cases, the volcanic mountain itself erodes away leaving nothing but the coral reef on top. Midway Island, furthest to the north, is one such atoll.
The State of Hawaii, about 2400 miles from its nearest neighbors, is one of the most remote spots in the world. Hawaii has had an unusual amount of rain this year. But when we had the chance to take a helicopter over Kilauea, we took it. Currently, there is no dramatic lava stream flowing into the sea. But the lava is bubbling up through cracks into lava lakes.
Click on photos to enlarge.
A lava lake
Lava pushes at the edge of a tube.
Newly cooled lava
Lava cools dramatically within seconds after reaching the surface. It turns to rock with a metallic sheen during the first few days and then to gray-black rock. But beneath this rock, red hot molten lava continues to force its way through tubes. Pressure builds until it again breaks out, cools on the surface and begins the process again. It will form a delta next to the sea which eventually breaks off, falling to the base and leaving a cliff through which red molten lava pours into the sea adding yet more land.
Since 1983, Kilauea has added about 500 acres to Hawaii.
Recent rain helps waterfalls look great
The volcanoes of the south pacific are “shield” volcanoes which erupt through cracks. Those on the Pacific “Ring of Fire” are “strata” volcanoes and often erupt explosively like Mt. St. Helens.