Hawaiian Volcanoes

James Raley

National University

EES 103

Final Paper

3/25/15

Hawaiian Volcanoes

The central area of the Pacific Ocean is the home of the Hawaiian Islands that span 2,400 kilometers long beginning at Kure Island, located in the northwest and forms a southeast-trend line to big island of Hawaii. This island is 3,000 kilometers away from the nearest continent, which is North America. Due to this curve of the islands the area is broken into two areas known as the northwestern (leeward) islands and the southeastern (windward) islands. The existence of islands of Hawaii is due to the claimed “hot spot” that began forming volcanoes as much as 70 million years ago in the southeastern area. The northwestern islands are a lower level chain that doesn’t project much higher than sea level, but the southeastern area is the home of the eight major islands and most of the volcanoes that will be discussed in this paper. Essentially, the key fact that makes the islands of Hawaii so unique and worthy of studying is that nearly the entire mountain range is built entirely by volcanic activity and each island is the top of an enormous volcanic mountain. These exceptional qualities fuel the study of how the islands themselves were created, in order to answer the curiosities behind the composition of some of the most extravagant volcanoes in the world (Wenkam, 1987).

The basic theory of plate tectonics says that all volcanic activity should occur between lithosphere plates. However, the Hawaiian Islands bend this rule by being located directly in the middle of the Pacific plate. The Hawaiian volcanoes are known as intraplate volcanoes. This may not seem possible because it disrupts the rule of plate tectonics, but there’s the exception of a hot spot. T. Wilson suggested that the Pacific plate moved in the northwestward direction over a melting spot deep within the mantle, and this hot spot remained relatively stationary and supplied magma to the moving Pacific plate to form the Hawaiian Island chain. In order to prove this suggestion, the structure of the Hawaiian Islands must be in line with a hot spot origin. (Macdonald, 1970).

         There are three structural trends that are recognized in the Pacific Basin to prove the accuracy of T. Wilson’s hot spot theory. The most obvious one is the northwest-southeast trend. This the most obvious due to the fact that is exactly how the Hawaiian Islands are formed and even divided up. Another trend is the north-south trend, which can be found north of the western tip of the Hawaiian Island chain known as the Emperor Seamounts. This island chain does indeed display a north-south trend line. Finally the last trend is fracture zones in the south of west Pacific plate. While this is not as obvious of a trend as the formation of the Hawaiian Islands, there are multiple factures zones in the south of west, which are along California and other areas along the Pacific plate, including the Hawaiian Ridge (Wenkam, 1987).

 While the structure of the Pacific basin and Hawaiian region coincide together the way they were supposed to in order for the hot spot theory to be true, Hawaiian volcanoes must also possess the characteristics of isolation and distinct lavas. The first characteristic is satisfied by the interior of plates being far removed from plate boundaries, and making up much less than 1% of the world’s total volcanic activity and associating with areas of broad crustal uplift, to produce linear island chains which have a characteristic age progression. The second characteristic in Hawaiian volcanoes is obvious because this area alone is known as having its unique type of eruptions due to the gentleness and dominance of fluidity in the lava. Despite the lack of information on how a hot spot is formed, the hot spot theory developing the Hawaiian Islands appears to be true (Wenkam, 1987).

 There are currently four main active volcanoes in Hawaii. The newest most recent one is Loihi, which is just south of the big island of Hawaii. While it is not quite as strong as the other three active volcanoes, it has a similar form to other three active volcanoes Hualalai, Kilauea and Mauna Loa. While Hualalai, located in the western, northwestern part of the big island in Hawaii, is not one of the most important or active volcanoes in the world, it is still the third most active volcano in Hawaii. The other two volcanoes are located in Hawaii Volcanoes National Park. Kilauea is known as the world’s most active volcano in the entire world and has been erupting continuously since 1983. Mauna Loa is known as the world’s most massive volcano. These three main volcanoes will exemplify many aspects of what makes Hawaiian volcanoes so unique. While those three volcanoes play a key role in developing a better understanding of Hawaii’s land, the previously active volcanoes have also played a significant role as to what Hawaii is today (Lipman, 2011).

 The previously active volcanoes include Halekala, Mauna Kea and Kohala. The Haleakala volcano is considered in active right now, but it does have long eruptive history when it was considered active, and there have been signs of activity over the years meaning that it might not be extinct. Therefore, despite the current status of the volcano, it can easily change. Mauna Kea is known as the highest volcano on the earth, and while it may have not had any eruptions in thousands of years, it is still unique because it glacial deposits and because it is so tall it receives snow at the top during the winter months. Another inactive volcano is Kohala, and it is important because it is more than 500,000 years old, making it the oldest of all the dry land volcanoes in Hawaii (Coombs, 2006).

 First of all there are two types of eruptions, which are magmatic eruptions and phreatomagmatic eruptions. Magmatic eruptions are caused through thermal expansion. Phreatomagmatic eruptions are caused by interactions between water and magma through thermal contraction. “Hawaiian-type eruptions” fall under the magmatic eruptions. There is a distinctive characteristic that is present in Hawaiian volcanoes that cause volcanologists to separately identify “Hawaiian-type eruptions.” This superior trait that is present in most of the Hawaiian volcanoes is the gentleness of eruption by erupting at low levels and having fluid-like lava releasing very little gas. Therefore, while a large cloud may be present thousands of meters into the atmosphere, it is mostly diluted by air. From previous eruptions of Mauna Loa and Kilauea, volcanologists have found that gas only forms about 1% of the weight of the erupting magma. As stated before, there is very little explosions and rather more fluidity in the lava, which is proven from many lava fountains that have reached hundreds of meters above the vent opening from jets of liquid lava shooting into the air for days. These lava fountains are more like streams of molten rock under pressure, shooting into the air, such as steam of water from a hose. “Hawaiian-type volcanoes” are considered to be the weakest of the magmatic eruptions, and this actually makes the islands a place a safer place to live (Coombs, 2006).