Mauna Loa Essay, Research Paper
Mauna Loa, which directly translated from Hawaiian means “Long Mountain”, refers to a volcano located in the South Pacific. It is one of the largest volcanoes in the world and makes up a large portion of the island we know as Hawaii. Since its birth, somewhere between 700,000 and 1,000,000 years ago, Mauna Loa has grown to over 13,680 feet above sea level. To this day, Mauna Loa continues to be one of the most studied volcanoes in the world.
Mauna Loa is an example of a shield volcano, resulting from the outpouring and cooling of basaltic magma above a hotspot. This is believed to be the same Hawaiian hotspot that created Mount Kilauea and Loihi seamount as the Pacific plate drifted. Its visible portion, rising only some 14,000 feet above sea level, is somewhat deceptive of its enormous size. The volcano actually sits at the bottom of a depression 26,000 below the ocean floor, and does not reach the surface of the ocean for another 16,400 feet. This gives the volcano a total height of more than 56,000 feet, making it by far the largest active volcano in the world. It has a summit that is sixty miles long and 30 miles wide. The majority of Mauna Loa’s surface is believed to be less than 10,000 years old, and resulted from many eruptions of very fluid lava flows. The low viscosity of the magma has caused both pahoehoe flows and a’as and given the volcano its gentle slope and shield-like appearance.
Mauna Loa’s first recorded account of volcanic activity was in 1840, when a guide by the name of Keaweehu took an exploration party to its summit. He explained that a major eruption took place there in 1780. Although we have no first hand account of this eruption, it is believed that there have been thirty-nine eruptions since 1832. The last of these eruptions was in 1984. The eruption began suddenly following a three year period of earthquake activity underneath the volcano. During the eruption, there were lava fountains as high as fifty meters, and four parallel lava flows moving at speeds of up to 215 meters per hour. This eruption had a volume of .22 cubic km. of debris and covered 48 square km. Other major eruptions include: June 1st, 1950, with a volume .376 cubic km. and 112 square km., August 9th, 1872, with a volume of .630 cubic km. and 5 square km., and January 23rd, 1859, with a volume of .383 cubic km. and91 square km.
Located at the peak of Mauna Loa is a summit caldera named Moku Aweoweo. This caldera was caused as molten rock was ejected from the volcano, leaving a vacancy in the ground underneath. The surrounding rock then subsided, leaving a huge crater. It is believed that the caldera was formed approximately 600 to 750 years ago. It is over 183 feet deep, and spans three kilometers wide, by 5 kilometers long. Most of the activity on the volcano is located here, where lava is ejected. The composition of the lava flows is primarily Silica, then Aluminum, followed by smaller amounts of Iron, Magnesium, Calcium, and Sodium.
In summary, it can be seen that there is much to learn about volcanoes, and serious planning needs to be done to avoid catastrophe. Mauna Loa gives us an example of how awesome these structures can be.