Objectives

1. Objectives • Volcanoes of the Island of Hawaii • Seven Shield Volcanoes Types of Volcanoes • Descriptions and Images Eruption Update Mahukona Loihi REGIONAL DISTRIBUTION

2. Shield Volcanoes of the Island of Hawaii How and why volcanoes erupt GG103 Nasir Gadzar

3. 5 Shield Volcanoes 2 Submarine cones Shield Volcanoes - Regional Distribution

5. REGIONAL DISTRIBUTION Red – recent volcanism on the ocean floor Green – Hawaiian islands Hawaiian Islands Pacific Ocean

6. Hawaii

7. Island of Hawaii The subaerial (rocky, above sea level) portion of the Island of Hawaii is made of five volcanoes. From oldest to youngest, they are Kohala, Mauna Kea, Hualalai, Mauna Loa, and Kilauea. Each volcano can be recognized by its size, shape, and physical features. Two other volcanoes, Mahukona and Loihi, add to the submarine base of the Island. Mahukona Pacific Ocean

8. Volcanoes of the Island of Hawaii, elevation, area.

9. Volcanoes are classified as: Active - These are erupting or keep erupting. Kilauea Dormant - These are not erupting but could at any time. Mauna Kea Extinct - These volcanoes are no longer active and do not erupt. Diamond Head Crater

10. 􀀹~1500 volcanoes are potentially actives on Earth 􀀹 ~ 70 are currently in eruption 􀀹 ~ 10% of the human population is directly exposed to volcanic risk. Several large cities are located close to an active or dormant volcano

11. Cinder Cones  - Cinder cones are the simplest type of volcano. They are built from particles and blobs of congealed lava ejected from a single vent. As the gas-charged lava is blown violently into the air, it breaks into small fragments that solidify and fall as cinders around the vent to form a circular or oval cone. Most cinder cones have a bowl-shaped crater at the summit and rarely rise more than a thousand feet or so above their surroundings. Cinder cones are numerous in Hawaii as well as throughout other volcanic terrains of the world.

12. Shields - Another easily recognized volcano which is familiar is the Shield volcano. This type of volcano can be hundreds of miles across and many tens of thousands of feet high. The individual islands of the state of Hawaii are simply large shield volcanoes. Mauna Loa, a shield volcano on the  island of Hawaii, is the largest single mountain in the world, rising over 30,000 feet above the ocean floor and reaching almost 100 miles across at its base. Shield volcanoes have low slopes and consist almost entirely of frozen lavas

13. The animation shows the steps in the formation of a caldera. The volcano usually shows signs of erupting by producing earthquakes as the magma rises in the volcano.

14. Calderas - Calderas, are simply circular depressions, are found on the summits of many volcanoes. "Giant" calderas are the largest of these: huge craters up to many tens of miles across. Giant Calderas form by collapse (see animation) in gigantic eruptions that spew volcanic rocks out hundreds or even a thousand miles in all directions. Sometimes the calderas are so filled with lava and volcanic ash that there is no recognizable depression at all.

15. After a huge ejection of lava there may be no magma left in the chamber to fill the conduit and crater. When this happens there is a hollow space under the summit of the mountain where the magma used to be. The top of the mountain then collapses creating a caldera.

16. The caldera may fill with water creating a lake.

17. REGIONAL DISTRIBUTION

18. REGIONAL DISTRIBUTION

19. Shield Volcanoes of the Hawaiian Islands Shield Volcanoes are enormous features built up only from layers of lava. They produce lots of A’a and Pahohoe lava flows but they tend not to erupt violently. Topographic Profile of Mauna Loa Basaltic Lava Flow 10,000m 250 kilometer

20. Hawaiian Islands Palaeogeographical Location of the various islands over the active volcanic activity (hotspot red circle) at different times

21. Kilauea magma hiding from volcano scientists:  Scientists at Kilauea Volcano are pondering the big question: Where is 250,000 cubic yards of magma going if it's not flowing each day to the Pu'u 'O'o eruption? Magma that forced its way into the upper East Rift Zone and caused hundreds of earthquakes finally cracked the surface.

22. Beware of lava from Kilauea.

23. A tour boat had a sea view of lava from Kilauea flowing into the ocean. Michael Marlin

24. Lava flows from Kilauea March 12, 2008

25. An abandoned pickup truck is engulfed in flames after lava from Kilauea came into contact with it.

26. A backyard swimming pool in the Royal Gardens area of the Big Island that was once filled with water is now filled with lava from Kilauea.

27. Stages of Growth of Volcanoes in Hawaii, 500,000 years ago

28. In order of growth, the volcanoes that make the island and its submarine base are Mahukona, Kohala, Mauna Kea, Hualalai, Mauna Loa, Kilauea, and Loihi. Mahukona, Kohala, Mauna Kea, and Hualalai have completed their shield-building stage. Mahukona slides into the sea

29. The island has grown at an average rate of 0.008 mi2/yr (5 acres; 0.02 km2/yr) for the past 600,000 years. It is estimated that 600,000 years was required for each volcano to grow from the ocean floor to the end of its shield building stage

30. Kohala Shield Volcano – Extinct volcano Most Recent Eruption(s)About 120,000 years ago Number of Historical Eruptionsnone Oldest Dated RocksAbout 460,000 years before present 46 万年間 Estimated Age of KohalaEmerged above sea level before 500,000 years ago Hawaiian Volcano StageTransition between postshield and erosional stage Location20.08 N 155.70 WElev. Above Sea Level 1,670 m5,480 ft Area 606 km2235 mi2(5.8% of Hawai`i) Volume 14,000 km3, 3,400 cu mi3

31. Mauna Kea – tallest volcanoe Most Recent Eruption(s)At least 7 separate vents erupted between about 6,000 and 4,000 years ago Number of Historical Eruptionsnone Oldest Dated Rocks237,000 ± 31,000 years before present 23 万年間 Estimated Age of Mauna KeaAbout 1 million years, 100 万年間 Volcano StagePost-shield Stage (transition from shield stage to post-shield occurred before about 200,000 to 250,000 years ago) Location19.82 N 155.47 WElev. Above Sea Level4,205 m13,796 ft Area2,380 km2920 mi2(22.8% of Hawai`i) Volume>30,000 km3>7,200 mi3

32. Mauna Loa Most Recent Eruption, March 24-April 15, 1984 Summit Caldera Name: Moku`aweoweo, "Moku" refers to a coastal land section or islet; "`aweoweo" is a type of red Hawaiian fish. Literal translation is fish section Dimension: 3 x 5 km, elongated northeast-southwest Depth: 183 m deep Age: estimated to have collapsed 600-750 years ago Oldest Dated RocksBetween 100,000 and 200,000 years ago Estimated Age of Earliest Subaerial EruptionsAbout 400,000 years ago Estimated Age of First Eruption of Mauna LoaBetween 1,000,000 and 700,000 years before present Hawaiian Volcano Stage: Shield-forming stage Location19.475 N 155.608 WElev. Above Sea Level4,170 m13,680 ftArea5,271 km22,035 mi2(50.5% of Hawai`i) Volume80,000 km319,000 mi3

33. Hualalai: Most Recent Eruption(s) 1800 and 1801 Location19.69 N 155.87 WElev. Above Sea Level2,521 m8,271 ft Area751 km2290 mi2(7.2% of Hawaii) Volume12,400 km32,975 mi3

34. Hawaiian Meaning The Hawaiian name "Kilauea" means "spewing" or "much spreading," apparently in reference to the lava flows that it erupts. Most Recent EruptionContinuous since January 3, 1983 Number of Historical Eruptions61, not counting the continuous lava-lake activity in Halema`uma`u crater Summit Caldera The caldera itself has no Hawaiian name other than Kilauea but houses the famous crater, Halema`uma`u; "hale" is a house, "ma`uma`u" a type of fern. Dimension: 6 x 6 km (outermost faults), 3 x 5 km (main depression) Depth: 165 m deep Age: probably several incremental collapses 500-210 years ago Oldest Dated Rocks23,000 years old Estimated Age of Earliest Subaerial Eruptions50,000-100,000 years Estimated Age of First Eruption of Kilauea300,000-600,000 years before present Hawaiian Volcano Stage Shield-forming stage Location19.425 N 155.292 W Elev. Above Sea Level1,277 m4,190 ft Area1,430 km2552 mi2(13.7% of Hawai`i) Volume25,000-35,000 km36,000-8,500 mi3

35. Loihi Seamount depth = 969 meters will reach surface in about 30,000 years

36. Volcano Safety Mahukona Loihi

37. March 19, 2008 Explosive eruption in Halema`uma`u Crater, Kilauea Volcano, is first since 1924 Volcanic gas escapes from a vent in the Halemaumau Crater near the Jaggar Museum inside Hawaii Volcanoes National Park. AP Photo/Marco Garcia

38. The explosion scattered debris over an area of about 75 acres (30 hectares), covering a portion of Crater Rim Drive and damaging the Halema‘uma‘u overlook. Rocks ejected by yesterday’s explosion at Kilauea volcano dug impact craters when they hit. Finer-grained material was blown away during the impact. Boulders and smaller rocks were scattered over a large area of Hawaii Volcanoes National Park, but no one was injured. March 19,2008.

39. Kilauea: an explosive volcano in Hawai`i Explosive eruptions at Kilauea are thought to be caused when water comes into contact with hot or molten rock (magma) and flashes into steam. In 1924, this happened after the level of the lava lake in Halema'uma'u Crater dropped below the water table. The walls of the crater then collapsed and blocked the opening down which the lava had drained, allowing steam pressure to build up and cause violent explosions.

40. Many of Kilauea's pre-1924 explosive eruptions that produced significant ash deposits probably happened when the volcano's summit crater was so deep that its floor was below the water table, letting ground water seep in to form a lake. Whenever magma erupted into the lake water, violent explosions of steam and volcanic gases resulted, fragmenting the magma into tiny ash particles and driving fast-moving, extremely hot ash-laden steam clouds (pyroclastic surges) out of the crater.

41. Kilauea eruption blasts rocks across landscape March 19, 2008. The most recent explosive eruptions before March 19, 2008 were in 1924 and were much bigger than the latest event. Those explosions killed a photographer, who ventured too close and was hit by falling rocks and hot mud. This explosive eruption at Kilauea on May 22, 1924, the cloud was 2 miles high and still rising. Geologists now believe such explosions were common in the past

42. Rocks litter the area around a wooden fence at the Kilauea volcano overlook. The fence was heavily damaged yesterday in the first explosive eruption at Kilauea volcano in almost a century.

43. The largest boulder to be blasted out of Halemaumau Caldera was almost about 3› feet wide. It landed on the steel cable of the barrier adjacent to the trail next to the Halemaumau Overlook. The recent increase in hydrothermal or gas sources had forced the explosive eruption, the first since May 1924. No lava was found in the area.

44. A near vertical view looks down into the explosion crater. The crater is estimated at roughly 100 feet across.

45. KAMEHAMEHA'S VOLCANIC VICTORY The most significant Kilauea eruption ever documented may have altered Hawai'i's history, according to records at the Hawaiian Volcano Observatory. Kamehameha I, before becoming king and uniting the Islands, was locked in an indecisive war with his rival, Keoua. In 1790, a sudden eruption of searingly hot ash and gas exploded out of Kilauea as a large group of Keoua's warriors and their families passed nearby. At least 80 and perhaps hundreds of people were killed in the deadliest historical eruption to occur in what is now the United States. That disaster helped tip the rivalry in Kamehameha's favor.

46. Pu'u 'O'o on Kilauea's East Rift Zone has been producing about 2,000 metric tons of sulfur dioxide a day for years, but only about 200 tons per day were being released at Halema'uma'u at the summit. That changed late last year when sulfur dioxide emissions from the summit began to climb, and by March 13 had reached record levels of 2,000 tons a day as a new vent opened in the wall of the crater.

47. Debris avalancheDebris avalanches are moving masses of rock, soil and snow that occur when the flank of a mountain or volcano collapses and slides downslope. As the moving debris rushes down a volcano and into river valleys, it incorporates water, snow, trees, bridges, buildings, and anything else in the way. Debris avalanches may travel several kilometers before coming to rest, or they may transform into more water-rich lahars, which travel many tens of kilometers downstream

49. Composition of Hawaiian Volcanoes Igneous Rock The term ``igneous'' comes from the Latin word ignis or ``fire''. Igneous rocks are rocks which form from cooling magma or lava. MagmaMolten or partially molten rock material and dissolved gases. Magma is molten rock beneath Earth's surface. LavaMolten or partially molten rock material and dissolved gases. Lava is molten rock which has erupted at Earth's surface.

50. Volcanic steam was rising yesterday from the MLK vent that has deepened on Kilauea