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Hawaiian Plate Tectonics
By Ishi and Jason
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Hawaiian Island Chain

• 3,700 miles long
• 70 million years old
• 5 connected volcanic mountains and a chain of
  submerged islands (Emperor Seamounts)
• Located on the Pacific Plate

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Pacific Plate Motion

• Moves W/NW at approx. 5-10 cm per year
• Currently being subducted beneath the N. American
  and Eurasian plates (Aleutian Trench)
• Moves over stationary hot spot in Earths mantle

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Hot Spot Theory

• 1963- Proposed by J. Tuzo Wilson
• Evidence
• Oldest Volcanic rocks of Kauai (most NW island)
  are dated at 5.5 million years old and greatly
  eroded.
• Oldest rocks of the Big Island are approx. 0.7
  million years old.

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Proof of Hot Spot Theory from Deep Sea Drilling
Program

• Several sediment cores were taken near the
  Emperor Seamounts and Hawaiian Islands
• Cores contained similar materials with similar
  compositions
• Showed that the seamounts and islands became
  older, moving northwest along the chain (the Big
  Island being the youngest)

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• Hot Spot magma from within the Earths mantle
  pushes up the Earths crust resulting in the
  formation of an undersea volcano.

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Hot Spot Facts

• Hot spots persist for 10 Ma-100Ma or more
• Some scientists have estimated the Hawaiian hot
  spot to be about 200 miles across (enough to
  encompass the currently active volcanoes Mauna
  Loa, Kilauea, Loihi, and possibly Hualalai and
  Haleakala)

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Island Formation

• An undersea volcano can reach the oceans surface
  after many eruptions, forming an island (millions
  of years)
• Sudden jerks in the plate movement create new
  volcanoes
• When the plate is moving slowly, it enlarges the
  current volcano
• All islands formed at same position (hot spot),
  current location due to plate motions

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Reject Islands(aka Seamounts and Guyots)

• Seamount submerged volcano (never reached the
  surface)
• Guyot ancient island, now submerged due to
  cooling of the mantle (causing crust to sink) as
  it moves away from the hot spot

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Shift in Plate Motion

• About 2,000 miles from Hawaii, the chain
  abruptly veers and extends North (at 33 N and
  171 E)

• About 43 million years ago, there was a global
  reorganization of plate motions, which changed
  the direction of the Pacific Plates movement
• The turn might have been due to the collision of
  India with Asia
• Before the shift, the rate of movement was 6cm
  per year

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Hot Spots in Action Mauna Loa

• Mauna Lao (located on the Big Island) is the
  largest volcano on Earth
• It began forming about 1 million years ago
• Estimated volume 40,000 cubic km

Mauna Lao makes up about ½ of the Big Island,
and it is one of the most active volcanoes on
Earth
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Mauna Loa has erupted 15 times since 1900, most
recently in 1984 Rift zone area of weakness
near the surface of the volcano that often breaks
open when magma rises during an eruption red
pahoehoe(smooth) yellow/white aa(rough)
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The Next Generation Loihi

• Located off the Southwest coast of Hawaii
• Currently, 6000 ft above the sea floor (about 1km
  from the surface)

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But

• Predicted to poke through surface in about 1
  million years.

So, dont make vacation plans just yet!