Mauna Loa's Last Eruption example essay topic

Mauna Loa: The Fiery Mountain Mauna Loa is Earth's largest volcano and most massive mountain as it takes up nearly half of the flourishing landscape of the island of Hawai'i. This island is actually made up of five volcanoes, Kohala, Mauna Kea, Hualalai, Mauna Loa, and Kilauea, all in such close proximity that they fused together to form one whole island. Mauna Loa is located in the south central area of Hawai'i, in the Hawai'i Volcanoes National Park and its coordinates are 19^05' N, 155^06' W. It is 13,680 ft above sea level, but if one measures from its true base on the ocean floor, it is estimated to be 30,080 feet tall. Its name is quite fitting as it means "Tall Mountain". Mauna Loa is located on a hot spot in the Pacific Ocean. It is not near a plate boundary, in fact it is 3,200 km from the nearest plate boundary, and is situated in the middle of the Pacific tectonic plate.

This is actually a rarity, as 90% of volcanoes are along a tectonic plate boundary. A hot spot occurs where long, stationary vertical pools of magma rise up and towards the plate. Movement of the tectonic plates above the hot spot created Mauna Loa, along with the other Hawaiian volcanoes. The older Hawaiian Islands were once above this stationary hot spot, but have been carried northwest by the slowly moving Pacific plate. As the plate moves, it carries the previously formed, older, volcanoes with it, creating a trail of younger, new volcanoes behind.

The islands are lined up along the Hawaiian Ridge-Emperor Seamounts chain, which is 3,750 miles and includes Kauai, Maui, Oahu and Hawai'i, from north to south, respectively. There are around 80 volcanoes in this chain; most of them underwater, consequently the term seamount refer to submarine volcanoes. Three volcanoes of Hawai'i, Mauna Loa, Kilauea and Loihi seamount, are all currently sharing the Hawaiian hot spot. Although, recent evidence has shown that all three volcanoes use have separate plumbing systems to expel the lava from the pool of magma deep below them. It has also been suggested that Loihi is slowly moving Mauna Loa from the center of the island, thus shifting directly over the hot spot. The closer to the hot spot a volcano is, the more active it will be.

The Hawaiian hot spot has laid down layers of lava, building up enormous islands from the ocean floor. Over time, the island of Hawai'i will shift away from the hot spot and make room for another, new volcanic island. Mauna Loa is a shield volcano, with wide moderate sloping sides. Shield volcanoes are created when lava emerges out from fissures in the earth's crust. Both a'a and pahoehoe flows erupt magma, which is magic, of low-viscosity, and the lava spreads out in thin layers. The eruptions from shield volcanoes are gentle and flow easily and are sometimes called "Hawaiian-type" eruptions.

Researchers have been studying the mineral composition on Mauna Loa for some time. They have been closely looking at its xenolith's, which are rock materials they may have been carried by lava, but not genetically related to the lava. Scientists have discovered numerous deposits of crystal-rich rocks from deep inside the volcano that were forced to the surface by volcanic eruptions. The minerals found included olivine, plagioclase, pyroxene, and combinations of all three. Some of the xenolith's are composed of minerals that are rich in magnesium and iron, while others are composed of minerals, which are rich in calcium. This indicates that the magma must have come across at least two separate chemical environments on its trek to the surface.

The xenolith's also show an array of textures that show having been in different physical environments. Most of the flows of Hawaiian volcanoes, 99%, are basalt flows and erupt magma as hot as 2,200 ^0 F. Since Mauna Loa erupts basalt flows, it magma contains around fifty percent silica and is rich in iron and magnesium. The origin of Mauna Loa's magma is still being researched. According to a 2002 U.S. Geological Survey article, Mauna Loa has a shallow magma reservoir beneath Moku', Mauna Loa's 4,000-plus foot deep caldera summit caldera, which is estimated to have collapsed over 600 years ago. The USGS website states: Geologists must rely on data gathered from rocks at the surface of the earth, combined with geophysical information. From these data they construct a 3-D model of the many magma chambers and conduits that extend several kilometers (miles) beneath the surface of the earth.

The lush environment surrounding Mauna Loa has enthralled the native people of Hawai'i and tourists alike. Just Mauna Loa, alone, incorporates ten different zones of vegetation. As the elevation increase on the volcano, so does the desert-like climate. Mauna Loa is also one of the world's most active volcanoes. Research indicates it has been erupting for possibly over 100,000 years from Moku'.

It has erupted 33 times since 1843 and releasing enough lava to cover 40% of the Big Island. Of all recorded eruptions, the most destructive began on June 1, 1950 and lasted 23 days. Lava erupted from the middle portion of the rift zone from a virtually unbroken fissure that was around twenty kilometers long. Traveling at five miles per hour, the lava reached the seashore in less than four hours.

Mauna Loa's last eruption began March 24 and lasted through April 15, 1984. The eruption began at the summit and lasted 21 days. The lava flow has been measured to be around 220 million cubic meters. It was a sudden blow, but seismic activity had been slowly increasing for three years. There was an estimated $62 million in damage caused by this eruption.

The lava advanced toward Hilo and came with a few miles of Kula ni Prison, but never did reach the cities. The current city limits of Hilo were once covered by lava in 1880. This shows that any eruption could cause serious damage to the newly developed farms, towns and cities surrounding Mauna Loa. As previously stated, 40% of Hawai'i has been covered by lava at some point in recorded history. Even with a disregard for the lava flow's destruction, other hazards of an eruption include pyroclastic flows, landslides, and volcanic gas. Sulfur dioxide is a common gas emitted during an eruption from a Hawaiian volcano and is potentially harmful to human health.

Any amount of sulfur dioxide can combine with water to form sulfuric acid, which can attack skin, cloth, metal and other materials. In addition to destroying homes, the flows cover highways and some residents are forced to move from their homes. Yet, development continues to thrive in areas considered especially hazardous. An estimated $2.3 million has been invested into new construction on Mauna Loa's slopes. There is not a clear way to forecast where the next eruption will spill lava unto the Big Island. Nearly 16 r% of the volcanoes surface has felt the avenues of scorching lava.

There are many pathways that could be traveled by the detrimental lava, but the point of eruption determines its route. Evidently, the people of Hawai'i do not let the fear of an eruption effect their daily lives. Even if an eruption is expected to occur, yet it could be anytime between the next few years and next few decades. As Mary Kaw ena Puk ui said in 1952:' It is profoundly significant that the Hawaiians of Ka'u did not fear or cringe before, or hate, the power and destructive violence of Mauna Loa. They took unto them this huge mountain as their mother, and measured their personal dignity and powers in terms of its majesty and drama'.

Bibliography

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United States Geological Society. 15 July 2005.
Mauna Loa". Wikipedia. 2005.
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Mauna Loa Volcano". Mauna Loa Information. 2004.
Hawaii Center for Volcanology. 15 July 2005.
Slumbering Giant". Extreme Science. 2005.
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