Olympus Mons and the Hawaiian Islands
From GeoClasses
Contents |
Initial Summary
In this project I will be talking about Olympus Mons, the highest known mountain in our solar system, and the Hawaiian Islands on planet Earth, which are shield volcanoes just like Olympus Mons on the planet Mars.
In addition to the two aforementioned geographical features, I would also like to briefly touch upon basic and general information about Olympus Mons, as well as common similarities between it and the Hawaiian Islands on Earth.
Obviously, I have not been to Mars. No man or woman of Earth has been to Mars. Therefore, any images, illustrations, pictures, or diagrams included in this project are sole property of said individuals and/or free to use via the internet by public domain. Any images used herein of the Hawaiian Islands are sole property of said individuals and have been used with permission.
Olympus Mons
This image here to the left clearly depicts how flat and large Olympus Mons really is. Even though the volcano is about 27 km in height, it is well over 20 times wider than it is tall. Therefore, most of the volcano has a more or less gentle surface slope. This image also depicts the distinct cliff which marks the base of Olympus Mons. In certain places, this scarp reaches up to 6 km in height. In other places however, it is hidden under lava flows cascading out into the surrounding lava plains on the surface. This cliff is very unique among the great shield volcanoes on Mars' surface. The crinkly, rough patches around Olympus Mons are also pretty unusual. They form what is called the Olympus Mons aureole.
Both the basal cliff and the aureole are poorly understood, meaning little is known about them. However, the origins of these areas may be related. There are many theories concerning their origins. In one theory, the basal cliff was formed by a series of numerous large landslides. The aureole therefore marks material piled up at the bottom of these landslides.
Volcanism
Olympus Mons is what is known as a shield volcano. It is a result of highly fluidic lava that flowed out of numerous volcanic vents over a very long period of time. It is significantly wider than it is tall. The average slope of Olympus Mons' flanks is very gradual. In the year 2004, NASA's Mars Express orbiter took images of old lava flows on the flanks of Olympus Mons. Based upon the frequency counts and crater size, the surface of this western scarp has been dated from 115 million years in age down to a region that is only 2 million years old. In geological terms this is very recent, which suggests that the mountain may yet have some ongoing volcanic activity.
The Hawaiian Islands on planet Earth are good examples of similar shield volcanoes on a much smaller scale. The enormous size of Olympus Mons is likely because Mars does not have tectonic plates. Therefore, the crust remained fixed over a hot spot and the volcano continued to discharge lava, bringing it to such an immense height.
The caldera at the peak of Olympus Mons was formed after volcanism stopped and the roof of the then emptied magma chamber collapsed inward. During the collapse the surface above became extended outward and formed fractures. Later on additional caldera collapses were formed due to additional lava production. These overlapped the original circular caldera, giving the edge a less symmetrical appearance.
Hawaiian Islands
The Hawaiian Islands were once called the Sandwich Islands. They to this day, form an archipelago of approximately 19 islands and atolls, a series of smaller islets, and a series of undersea sea-mounts stretching northwest by southeast in the area of the North Pacific Ocean between latitudes 19°N and 29°N. This archipelago receives its name from the largest island in the group and extends somewhere around 1,500 miles (2,400 km) from the Island of Hawaiʻi in the southern region to northernmost Kure Atoll. Besides Midway, which is an unincorporated territory of the United States of America, the Hawaiian Islands form what is known as the U.S. state of Hawaii.
This beautiful archipelago also represents the exposed peaks of an immense undersea mountain range called the Hawaiian-Emperor sea mount chain, which was formed by volcanic activity over or above a hot spot in Earth's mantle. Somewhere near 1,860 miles (3,000 km) from the nearest continent, the Hawaiian Island archipelago is by far the most isolated grouping of islands on planet Earth.
Hawaiian Hot Spot Geology
The Hawaiian islands formed as the Pacific plate moved very slowly in a northwestward direction over a hot spot in Earth's mantle at about 32 miles (51 km) per 1 million years. Therefore, the islands in the northwestern area of the archipelago are much older and typically smaller, because of their longer exposure to erosion. The only active volcanism known to man in the past 200 years has been located on the southeastern island, Hawaiʻi, and also on the submerged, but growing volcano at the extreme southeast, called Loihi. The (HVO) Hawaiian Volcano Observatory of the (USGS) United States Geological Survey records recent volcanic activity and provides many images and numerous interpretations of the volcanism that occurs there.
Almost, but not all magma that has been created in the hot spot has the composition of basalt, and therefore the Hawaiian volcanoes are constructed almost entirely of this igneous rock and its coarse grained equivalents, which are gabbro and diabase. A small number of the igneous rock types with compositions different from basalt, such as nephelinite, do occur on these islands, but are extremely rare indeed. The vast majority of eruptions in Hawaiʻi are Hawaiian type eruptions because basaltic magma is for the most part fluid compared with magmas typically involved in more explosive type eruptions, such as the andesitic magmas that create some of the spectacular, yet dangerous eruptions around the margins of what is known as the Pacific basin.
Hawaiʻi (also called the Big Island) is by far the largest and youngest island in the Hawaiian chain. It was built from five different volcanoes. Mauna Loa, which comprises well over half of the Big Island, is the largest known shield volcano on planet Earth. The measurement from the sea level to the summit is easily more than 2.5 miles (4 km). From sea level to sea floor it is about 3.1 miles (5 km).
References
Arnett, B. "Mars." Retrieved July 2, 2008. Used with permission. http://www.nineplanets.org/mars.html
Flament, I. (1996). "The Ocean Atlas of Hawaii." Department of Oceanography, Honolulu, HI. http://radlab.soest.hawaii.edu/atlas/ Used with permission.
Macdonald, G.A., Abbott A.T., & Peterson, F.L. (1984). "Volcanoes in the Sea. The Geology of Hawaii." 2nd edition. University of Hawaii Press, Honolulu. 517 pp.
Morgan, J.R. (1996). "Volcanic Landforms", Hawai'i: A Unique Geography, Honolulu, HI:Bess Press, ISBN 1573060216.
Rieke, G.H. "Mars -- The Red Planet." Retrieved June 30, 2008. Used with permission. http://ircamera.as.arizona.edu/NatSci102/NatSci102/lectures/mars.htm
Webmaster. "Exploring Mars." Retrieved June 30, 2008. Used with permission. http://www.exploringmars.com/science/olympus_mons.html
Webmaster. "Olympus Mons." Retrieved June 30, 2008. Used with permission. http://www.olympusmons.com/
