The towering summits and unique topographical landscape of Hawaii are a direct result of the geological processes that created grandiose volcanoes. Hawaii Volcanoes National park is home to two awe-inspiring volcanoes: Mauna Loa and Kilauea. Both members of the park are not just active, they’re are recognized some to be some of the most active in the world.
Five volcanoes make up the Big Island of Hawaii: the park’s volcanoes, Mauna Loa and Kilauea, and Hualalai, Mauna Kea, and Kohala. All these volcanoes are shield volcanoes, resulting from numerous basaltic lava eruptions that run down and cool, creating a shield like exterior. The Big Island volcanoes are known to exhibit lava tubes, which allow the lava to travel even further by keeping it insulated underground. In some instances, lava drips harden as they fall, creating lava stalactites (Harris et al, 2004). Kazamura is an example of a well-known lava tube that has hardened and become a large cave. It was once a Kilauea tube, surveyed at 40 miles long and over 3,600 feet deep (Foer, 2017).
Kilauea is the youngest shield volcano in Hawaii as well as the most active, boasting one of the longest (mostly) continuous eruptions on earth, mainly attributed to the Pu’u O’ vent. Since the beginning of the 1983 eruption, sixty-one eruptive episodes have been recorded, posing danger to the surrounding areas (USGS). The volcano has a large central crater with significant cultural value; Halema’u’mau is said to be the home of the goddess Pele and formerly featured a lava lake (Volcano Discovery, 2018). Mauna Loa, the largest active volcano in the world, makes up half of the area of the island. The Moku’aweoweo Caldera is the location of most of its eruptions, with some occurring along rift zones (Encyclopedia Britannica, 2018). Both Mauna Loa and Kilauea demonstrate two chief rift zones, with Mauna Loa’s growth sprouting from zones extending to the southwest and northeast from the caldera, and Kilauea’s highly studied east rift and seaward flank now being pushed south due to dike intrusion. Kilauea’s vents only form over rift zones, while Mauna Loa also displays radial vents on the north and west flanks (OSU). The lava erupted from these volcanoes is basaltic in composition, making it low silica and low viscosity, with Mauna Loa generally exhibiting larger and faster flows (USGS). Rhylolite is very uncommon in Hawaii (unlike Yellowstone National Park) but creates smooth, precious obsidian when cooled too quickly to form crystals on Pu’u Wa’awa’a, a cone of Hualalai (Oskin, 2013). Hawaiian terms are designated for different lava flows to describe surface morphology; `a’a is used to classify sharp fragmented flows, while panhoehoe describes smoother and billowy surfaces; often, panhoehoe is the cause of lava tubes. Lava can be shot into the air while a lava lake is active or a flank vent erupts for the first time, producing a lava fountain that can range anywhere from inches to over one thousand feet tall (nineteen thousand feet, in the case of the 1959 Kilauea Iki fountain). Pu’u O’o, the cause of the ongoing Kilauea eruptions, has presented many occasions of lava fountaining. (Harris et al, 2004)
The two basaltic suites in Hawaii are tholeiitic and alkalic, with tholeiitic basalts contributing to ninety nine percent of the shields and alkalic basalts making up just one percent, mostly concentrated on the cap (Harris et al, 2004).
Much like Yosemite National Park, Hawaii Volcanoes National park is a hotspot, and does not lay on a fault. Instead, the heat from the outer core radiating to the mantle brings hot rock upward in a mantle plume. The low pressure in the upper mantle causes the rock to melt into magma and rise to the surface. A volcano forms over the hotspot; the lithosphere continues to move over the spot, creating a chain of volcanoes as it’s travelled over (Mattox, OSU). In this way, Yosemite National Park and Hawaii Volcanoes National park receive their magma in very similar processes.
The Hawaiian-Emperor seamount chain is an example of a hotspot chain, with Kilauea and Mauna Loa being the younger end of the chain. A rather curious characteristic of the chain is the sixty-degree bend, thought to have been caused by the change in Pacific plate motion, with some kind of southward plume motion involved (Helmholtz Association of German Research Centres and Doubrovine, 2017). As the floor continues to move, a new volcano begins to build south of the island. Loihi is a submarine volcano that is said to resemble Kilauea and Mauna Loa, with a caldera three miles in diameter and what is predicted to be two rift zones (USGS). Pillow lava, a lava formation that occurs when it’s quickly cooled underwater, is young and glassy here.
While a magnificent display of geology, Hawaii volcanoes are an extreme danger to surrounding areas. The beginning of Kilauea’s eruption in 1983 has drastically transformed the landscape, captured hundreds of homes, and demolished infrastructure. It has been known to emit phreatomagmatic explosions, instances that occur when the lava or magma mixes suddenly with groundwater. This event can produce cinder cones, ash, and pyroclastics. Moreover, lava interacting with seawater presents a serious hazard: lava deltas, land created as panhoehoe lava meets the ocean, can collapse abruptly, prompting great explosions and triggering waves of blistering water. The breakdown can occur whenever the delta’s support shifts, usually rock debris. The event can cause plumes of steam that shower glass particles and hydrochloric acid below (USGS). Earthquakes also plague the area, such as the K?«holo Bay magnitude 6.7 earthquake in 2006 (HVO, USGS). Additionally, Vog, volcanic smog composed of SO2 and aerosols (small particles of sulfuric acid created when volcanic gasses mingle with oxygen and sunlight) poses a serious health risk to those who come in contact with it (USGS). Five tourist deaths were attributed to SO2 exposure from 1983 to 2003, with even more cases of respiratory related deaths that were not directly blamed on the gasses from the volcano. While the volcano presents many dangers, humans tend to be the cause of their own demise. Many other deaths in the park were cause by motor vehicle or airway accidents, responsible for nearly 68% of park deaths from 1993-2002 (Sprowl, 2014).
Beauty is not often a byproduct of danger, but in the case of Hawaii Volcanoes National Park it is. The spectacular hot spot geological processes that gave birth to the towering volcanoes are also what causes them to be a threat to the area surrounding, balancing oasis like beauty with uncontrollable hazards. The residents of the area must be daring yet cautious, but receive a more than generous reward for their bravery. The chain of hotpot volcanoes continues to grow, ensuring that the splendor will not soon cease.
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