EES 180 Notes pg. 2 - Hawaiian Volcanoes PDF

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Hawaiian Volcanoes...

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Hawaii Volcanoes NP Lecture 2 Mauna Loa Volcano ! - “long mountain” in Hawaiian ! - Classic shield volcano; worlds largest volcano; volume - 20,000 cubic miles (bends the mantle)! - Erupted more than 35 times since the island was first visited by westerners in the early 1800’s ! - Elevation above sea level - 13679’ (rise 8 km or 5 miles)! - Most recent eruption 1984 (3 weeks) ! - Barren on the mountain; not much going on; Mauna Loa observatory is famous ! - Historic measurements of atmospheric CO2 at Mauna Loa Ob. ! - Moku’aweoweo: central caldera (crater that has collapsed) ! Rift Zones! - the island cracks apart (fracture zones) ! - Darkest black rock is the newest (grey is older flows) ! - Dark brown flow (age and get altered and then turn it to a brownish color)! Curtain of fire! - a fissure gushes lava and then lava on the side will build a small wall/barrier on the sides of it ! Pahoehoe flow! - liquidy flow: thin skin and runs still; really hot; wrinkles into the flow and creates “ropes”! - Aa flow: rock fragments and are less fluid; just rocks falling down and are drier (less gasses from the eruption) ! Kilauea Volcano ! - shield volcano; have summit calderas and rift zones ! - Eruption in 1790 and then continuous record of more eruptions ! - 1983 eruption - biggest one ! - Eruptive vents at Kilauea: Manaa Ulu 1969 to 1974 and Pu’u’ O’o - 1983 to 2018; Kilauea Caldera 2008 to 2018; Leilani Estates 2018 to present ! - Kilauea caldera and halemaumau pit crater and Kilaeau Iki crater ! - Hale crater had reacent activity from 2008-2018 and filed up with lava and made a lava lake and overflowed the crater ! - Now ongoing collapse of the crater ! - Iki: filled with lava in 1959; now dried up (would drill and map the progression of the cooling process of the caldera)! - Took 29 years to cool the lava lake ! - Pu’u O’o vent (1983-2018! - Initial part in eruption in 1983; lava fountains ! - Lava channels and flows but also looses heat and starts to form into basalt as it moves (also the top forms faster than the interior) which then creates a lava tube that is trapped underground but is easier travel! - Roof caves in and creates a skylight ! - Thurston lava tube near Kilauea Iki ! Submarine landslides, mage tsunamis, and slumps ! - subsurface sonar surveys off of Hawaii in 1970’s and 1980’s ! - Landslide debris ! - Slump and avalanche deposits adjacent to Hawaii ! - Slumps: slow moving areas (unstable mass of rock moving)!

- Avalanche: fast moving ! - Largest Hawaiian avalanches have volumes on the order of 5000 km; making them the largest known slope !

- Tsunami waves from landslides ! - Regular: wind generated wave ! - Tsunami wave in deep ocean (not tall, but larger distance and really fast speed) ! - As approach shore, speed slows down a bit but really tall ! - Alika 2 ( last major submarine landslide off of Hawaii) ! - Tsunami deposits: larger fragments of basalt, sediments with marine fossils and coral fragments; and deposits overlie an ancient soil !

- Hilina slump! - Area is moving towards sea !

Kilauea: Closeup of an Active Volcano - magma (under the crust) lava when it is on the surface ! - Kilauea - eruption in 1983 over east rift zone ! - Short vigorous lava fountaining over a Spain of a few days ! - July 1986: less dramatic but more destructive - lava in depth over 50 miles on the flank of the volcano (effected the royal gardens area) ! - Destroyed the visitor center ! - Lava shield - mini parts of the mountain; cools and forms a crust and then the moving magma underneath move the plates ! - Subduction: one plate collides with another and one slides under another! - Lava flows: pahoehoe and Aa ! - volcanic glass - something hair that is like cotton candy! - Combustion of plants - create methane gas - concentrated and become explosive ! - Lava is insulating when entering the water; but if going fast then creating explosion ! - Black sand: wave shattered sand ! - Benches - underwater pile of rubble !...