Saturday, January 26, 2008
Emergent Steam creates Holes in the cooling Lava, as the groundwater below the new flow is overheated.
Hawaii Volcanic Oddities
The large island of Hawaii is one where a visitor can trace the history of lava flows and their effects on the Land Surface. There has been a historical and present documentation of flowing Lava, as it moved downhill from both Mauna Loa (long mountain) and Kilauea (spewing or spraying, in local lingo) Caldera. Houses have been photoed as they burned from advancing flows, and vegetation has been observed to be encapsulated. The flows are very deliberate, moving at speeds where people can escape them (but not so, for dwellings). Citizens have thrown up barriers, via bulldozers, usually to no avail. But when successfully diverting flows away from houses, they were later sued by neighbors for moving flows onto other properties. Now it is agreed that Pele- the goddess of fire- will get her way, and people must absorb her actions. Covered or burned houses and highways must simply be by-passed for new construction.
Pahoehoe Flows The ropey lava is the easiest for man to adjust to, since the surface is smooth and has low compressive and shear strength. It may be walked on and broken with a pick or hand tool. Vegetation finds the fractures which form upon cooling and begin to grow tall in them within ten years.
Ropey Lava or Pahoehoe
Slow-flowing Lava, such as Pahoehoe, is easy to tread and for fast-growing vegetation to weather (into the numerous shear cracks).
Flora-dated Basalt (instead of Petrified Wood)
Notice the “Tree Rings” made of successive lava insertions in holes left by burning layers of wood. Evidently Lava encapsulated trees before burning, which slowly burned the next layer before filling and burning another layer for subsequent filling.
Small subsidiary Craters
Minor Craters and Domes are due to subsurface flows from the Main Reservoir under Hawaii. This Reservoir may be many miles in diameter, originating from the primary vertical conduit under Mauna Loa- which is much smaller in diameter.
Lava travels long distances through Tubes, emerging unannounced
Notice the side-by-side Crater and Dome, named Mauna Ulu, which are distant from the main Kilauea Caldera. The Reservoir feeding these emissions is wide laterally, but spreads laterally from the main Throat which is only on the order of a mile in diameter (as evidenced by analysis of mineral composition).