Formation Of Hawaiin Islands


Formation Of Hawaiin Islands Essay, Research Paper

The Formation of the Hawaiian Island Chain

The Hawaiian Islands are one of the most beautiful and popular island chains in the world. Millions of tourists visit the islands every year to experience the great treasures that they have to offer. People see Hawaii as an ideal vacation spot for many reasons including; a year round tropical climate, the lush vegetation, and the numerous black sand beaches. However, the Hawaiian Islands are not only pretty to look at. The Islands possess unique geological aspects that make it possible for the islands to have these desirable characteristics. The Hawaiian Islands were not pieces of a continent that drifted out to sea, but were actually created by volcanoes in the middle of the Pacific Ocean. The process in which this chain of island is formed is quite intriguing and complex. The different steps include the presence of a hot spot, the emergence of an oceanic volcano, the plate tectonics of the region, the submergence of the older volcanoes, and the dynamics of the active Hawaiian volcanoes.

Hawaii consists of many volcanoes that were produced by a feature known as the Hawaiian hot spot. A hot spot, or plume, is a large column of magma, molten lava, which rises from deep within the Earth s asthenosphere (Monroe 332). The magma that comes out of these columns is so hot that it can melt through the layer of earth on top of the asthenosphere, called the mantel, and through the Earth s crust (the top layer of the Earth). There are only forty known hot spots that exist today. Hot spots can be found under a continent or an ocean, at a mid-ocean ridge and even in the center of a plate, like the Hawaiian hot spot (Duxbury 78). Each hot spot channels hot material at its own unique time intervals. Hot spots are generally stationary, however; their positions may change slightly. A typical hot spot has a life span of about ten million years (Duxbury 78). They are great sources of new material for the Earth s crust and can create, not only one, but a chain of islands.

The emergence of an oceanic volcano is only the beginning of an island chain. When a hot spot is active it will push magma up to the crust above, to create a volcanic peak if on land, or seamount if in water. The primary volcanoes on each of the Hawaiian islands are called shield volcanoes. They are described as gently slopping mountains, looking much like the outer surface of a shield lying on the ground. They are created by numerous lava flows that slowly spread out and harden in very thin layers (Rubin 1). After the building of layer upon layer the volcanoes eventually cut through the surface of the ocean forming an island (Rubin 2). The eruptions of shield volcanoes tend to have a quiet, smooth outpouring of thick, flowing magma rather than a sudden explosion (Duxbury 73). However, on occasion, some of the Hawaiian volcanoes, such as Kilauea, have produced large explosions. Explosions usually only occur when the magma mixes with groundwater, creating instant vaporization. Some of Hawaii s shield volcanoes have lava fountains that spew up from the top of the volcano that can reach as high as 400 meters (Monroe 89). The average Hawaiian volcano can remain active for hundreds of thousands of years before being carried away from its hot spot by the moving pacific plate (Rubin 2). The volcanic activity within the sea around the islands is believed to be a factor in the fact that the surrounding waters are about 83 degrees F year round.

The plate tectonics of the Hawaiian Island region play a major role in the formation of this unique island chain. As the hot spot forms and fuels a volcano, the pacific plate is continuously moving westward. Since hot spots are stationary the moving plate carries the volcano with it, cutting off the constant supply of magma. Without the magma reserve the volcano can no longer erupt, leaving it inactive. After the volcano is moved the hot spot will no longer have an outlet for magma. Soon after the plume will erupt once again and create a new volcano to replace the one it had just lost. As the pacific plate continuously moves across the Hawaiian hot spot consecutive eruptions have created the linear order of the islands. The plate moves over the asthenosphere northwest at a rate of 5 to 7 centimeters per year (Rubin 1). The age of the Hawaiian Islands tend to get older as they are observed from the southeast to the northeast (Rubin 2). In summary, when compared to an active volcano currently under the hot spot, the other volcanoes continue to drift westward while at the same time they are getting older. One of the northwestern most islands, Kauai, is estimated to be formed 3.8 to 5.6 million years ago, whereas Hawaii, the island currently under the hot spot, began forming less the one million years ago (Monroe 102). The land features of the different islands also tell a tale of their ages. The island of Hawaii shows little signs of erosion. On the other hand, an older island, like Oahu, exhibits many signs of erosion caused by their continuous movement as well as elements like wind and rain. The creation and the motion of the Hawaiian Island chain are a very useful tool in helping geologists to explain the movement of the pacific plate.

The submergence of old volcanoes is another part to the cycle of island chains. As the islands move away from the hot spot the plate cools and contracts. In combination with the contracting of material, the weight of the volcano and the erosion factors, the resulting effect is one of a depression. The volcano eventually sinks lower and lower until it is no longer above the surface of the ocean (Duxbury 78). Beyond Kure, the oldest, most western island, the Hawaiian Island chain continues with a string of submerged former islands. These islands are known as the Emperor seamounts (Rubin 2). As the seamounts slowly sank, coral began to grow upward creating coral reefs and further refining the beauty of the region.

The dynamics of the active volcanoes within the Hawaiian Island chain are still at the beginning of the island chain cycle. There are currently three active volcanoes in Hawaii. Two of them are on the island of Hawaii, Mauna Loa and Kilauea. The other one is a submarine volcano, called Loihi, which has not yet, broke the surface of the ocean. All three of the volcanoes share the Hawaiian hot spot. Mauna Loa is the largest volcano in the world with volume of 9,600 cubic miles and rising 13,677 feet into the air above sea level. Mauna Loa seems huge in comparison to the volume of Mount Shasta at 40 cubic miles, the largest volcano on the continental United States. This volcano itself makes up over 50% of the entire state of Hawaii (Mauna Loa 2). Because of the great mass of Mauna Loa the sea floor has a depression five miles beneath the enormous volcano (Mauna Loa 1). Mauna Loa is considered one of the most active volcanoes on the planet having erupted 33 times in one hundred fifty-seven years. However, Kilauea tops that having 34 eruptions in only forty-eight years, not including its continuous lava-lake activity (Urnezis 1). The name Kilauea means, spewing in Hawaiian, referring to the constant lava activity. Its most recent eruption has been continuous since January 3rd of 1983 (Kilauea 2). This volcano consists of about 14% of Hawaii. Loihi, on the other hand, is not an island, but an underwater seamount. It represents the first stage of the formation of a new Hawaiian island. The seamount rises over 10,100 feet above the sea floor and is only 3,100 feet within the surface of the water (Loihi 2). Loihi is an active volcano that frequently generates earthquakes. Scientists from the University of Hawaii have conducted many dives to Loihi in order to assemble data gathering interments on the summit of the volcano (Loihi 2). The data collected from these interments will give scientists an opportunity to study the geological phenomenon in greater detail. The active Hawaiian volcanoes are found to be the youngest within the chain, however, they can show a great deal about what the more western volcanoes looked like while under the Hawaiian hot spot.

The geological aspects of the Hawaiian Island chain continue to stimulate interest in members of the geological society. Comparing the age and distances in between each island can help scientists to calculate the speed of the movement of the pacific plate. This information aids in the better understanding of plate tectonics in general. In addition, the information can help to predict where the plate will go by studying where it has been. The cycle of the Hawaiian Islands: the birth of a seamount, the growing of an island, the shift in the crust and the decay and submersion of a volcano, is an example of the how the Earth constantly renews and recycles its material. Before these islands submerge into the sea in millions of years from now, it is important for mankind to investigate, explore and enjoy the events and characteristics shaping the Hawaiian Islands. This is important, not only to gain a greater understanding of the planet as a whole, but to also appreciate the tropical paradise that Hawaii is known for. The Hawaiian Islands are so diverse that if a tourist were to go there during the Hawaiian winter they could chose to partake in a range of activities from skiing on snow capped mountains in Hawaii to exploring the dry desserts of Kau, also on Hawaii. There is no wonder why so many people chose this place, all alone in the middle of the Pacific, to spend their hardly earned vacation time.

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