The Hawaiian hot spot
A chain of 107 volcanoes – some islands, some submerged – extends from Hawaii to the northwest. This 6,000-kilometer-long chain begins with the still-submerged Loihi. Moving northwest, the volcanoes become progressively older. The chain forms as the Pacific plate creeps at 9 centimeters a year over a stationary hot spot in the mantle that has been providing magma for 80 million years. The sharp bend records a shift in the plate’s direction of movement that took place 43 million years ago.
Lavas of Hawaii
The Hawaiian lavas are mostly basalt. Basaltic rocks contain high proportions of calcium, magnesium, and iron relative to silicon. For this reason, the lavas are fluid, having the consistency of honey. Instead of erupting in great explosions as Mount St. Helens did, the lavas form slow-moving molten rivers.
Topic: Earth Science
Keywords: Geology, Structural, Plate tectonics, Volcanic eruptions, Volcanism, Volcanoes--Hawaii
Aa (pronounced “ah-ah”) lava is more solidified and flows sluggishly compared to its more fluid counterpart, pahoehoe.
Pahoehoe (“pah-hoy-hoy”) is a form of lava produced by hot, fluid magma.
A spatter cone is created when blobs of lava are thrown into the air from a single event.
Lava may congeal around a tree to form a mold on the trunk and branches.