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Causes and Impacts of the 2018 Kilauea Eruption

Introduction

Hawaii is a term used to refer to an archipelago of islands located in the north-central pacific ocean, with the largest island sharing its namesake. On the third of May, 2018, the active island volcano Kilauea began to experience a surge in activity, followed almost a day later by a magnitude 6.9 earthquake, and subsequent fissures forming up to almost 40km from the base of the volcano (Skilling and McGarvie, 2018). These earthquakes and fissures continued to persist for around two weeks until May 17, when the volcano explosively erupted, causing considerable damage to the environment and society living in its proximity, and to the environment and economy of Hawaii as a whole.

Geological Processes

Kilauea is no stranger to volcanic activity, having been continuously erupting since the start of 1983 (Skilling and McGarvie, 2018). To understand the nature of what may have produced such a rapid eruption event, one must first understand the geological nature of the islands themselves.

It is commonly accepted that one of the main mechanisms driving the formation of volcanic island chains is the presence of so called hotspots within the lithosphere (Boer and Sanders, 2002). As the plate moves over this spot, the surface immediately above becomes increasingly more plastic as it is heated, and allows rock from the asthenosphere to rise to the surface and cool, gradually forming volcanic vents as a result. (Boer and Sanders, 2002). Even as the effected area of the plate moves away from the hotspot, the immense pressure on the asthenosphere caused by the depression of the plastic lithosphere above drives up swelling at the boundaries of the hotspot. As the vents move over these areas of up-swelling, fissures can from as pressure is exerted on the cooling lithosphere, allowing for even further development of volcanic activity (Boer and Sanders, 2002; Clague and Dixon, 2000).

Island volcanoes such as the Hawaii archipelago are often referred to as interplate volcanoes, origins and location within the centre of the plate rather than at a boundary (Klugel and Klein, 2006). As interplate volcanoes evolve, chambers of magma begin to from in the underlying lithosphere beneath them, these chambers house pressurized reserves of magma, and are continuously fed by the rising magma from the underlying asthenosphere and melting lithosphere (Klugel, A. & Klein, 2006). As the magma is under a massive amount of continuous force, any slight discrepancy in the strength of the walls of the chamber enables the magma to follow a path of least resistance and escape, sometimes forming new smaller "embryonic" chambers (Klugel, A. & Klein, 2006) and sometimes breaching the lithosphere and escaping to the surface as lava. When the latter occurs underwater, this usually results in the formation of a new volcanic vent, however terrestrial escape can result in eruptions such as the one observed in 2018. Terrestrial escape usually occurs at "summit reservoirs" located, as the name suggests,at the summit of the volcano in the from of an open 'crater' flooded with plastic rock (Pietruszka, A.J. & Garcia).

The evolution of the systems of magma that reside underneath the Hawaiian archipelago is driven by a combination of factors, the two most prominent being the temperature of the lithosphere, controlling the rate of magma crystallization as it rises to the surface, and the pressure that the underlying plate exerts on the asthenosphere and within magma chambers, controlling the where and how rapidly the magma rises (Clague and Dixon, 2000).

It can be deduced that one of the major contributing factors to the 2018 eruption was the earthquake that occurred early into the initial rise of activity. It is likely that the earthquake was the result of a breach forming in one of Kilauea's magma chambers, allowing magma to flow to the surface on the volcanoes side. The earthquake would also serve as the catalyst for the formation of the numerous active fissures around Kilauea's base. This rise in activity subsequently increased flow to the main summit reservoir of the volcano, leading to the constant earthquakes, and to the explosive eruption that occurred two weeks into the event.

Effects of the eruption

In their 2002 text "Volcanoes and Human History", authors Jelle Zeilinga de Boer and Donald Theodore Sanders propose a "vibrating string" model (Figure 1) for the effects that a volcanic eruption event has on the environment and human communities.

Boer and Sanders
Boer and Sanders "vibrating string" model of the impact of a volcanic eruption event.

When applying this model to the Kilauea eruption, it is possible not only to identify already occurring effects, but to predict future impacts.

The initial impacts of the eruption involved the immediate outputs of volcanic activity, with lava flows destroying large areas of wilderness and human cultivated land a property. Toxic gasses and volcanic dust released during the eruption would render the atmosphere around the eruption site inhospitable for terrestrial life, including humans, causing significant health risk to those that were unable to escape the proximity of the volcano, as well as preventing any immediate action from being taken to reduce the impact of the damage (Skilling and McGarvie, 2018). The environmental damage of the eruption devastated local environments, leading to large areas of land becoming "dead" and irrecoverable in the short term (Atkin, 2018). Long term ecological and environmental effects of the eruption will most likely include the formation of new niches in the changed ecological environment.

Economic impacts were felt almost immediately as businesses were (quite literally in some cases) burnt to the ground, and tourism to the entire archipelago plummeted in the wake of the May 17 explosion (Skilling and McGarvie, 2018). No doubt these impacts will be felt for many years to come as the island community and ecosystem attempt to recover.

Preventative measures

As precention of an eruption itself is, for the moment, outside of human technological capabilities, action needs to be taken to lessen the effects of eruptions even before they occur. As observed in the Kilauea eruption, major volcanic activity is usually preceded by earthquakes, smaller lava flows, fissures and other signs that indicate the possibility of an eruption. These warming signs can be followed and populated areas within relevant proximity to the volcano can be evacuated, lessening the immediate impact of the eruption on human life (National Geographic). When considering ecosystem and property damage, the immediate effects, much like the eruption itself, are nearly unavoidable. Action should be taken afterwards to refurbish human constructed areas, and to push devastated ecosystems in the direction of self recovery.

Reference List

Atkin, E. 2018, "What Is Kilauea’s Impact on the Climate?", [ONLINE] Available at: https://newrepublic.com/article/148542/kilaueas-impact-climate/. [Accessed 1 September 2018].

Clague, D.A. & Dixon, J.E. 2000, "Extrinsic controls on the evolution of Hawaiian ocean island volcanoes", Geochemistry, Geophysics, Geosystems, vol. 1, no. 4.

Boer, J.Z. & Sanders, D.T. 2002. "Volcanoes in Human History", Princeton University Press.

Klügel, A. & Klein, F. 2006, "Complex magma storage and ascent at embryonic submarine volcanoes from the Madeira Archipelago", Geology, vol. 34, no. 5, pp. 337-340.

National Geographic. "Volcano Safety Tips, Preparation, and Readiness" [ONLINE] Available at: https://www.nationalgeographic.com/environment/natural-disasters/volcano-safety-tips/. [Accessed 27 August 2018].

Pietruszka, A.J. & Garcia, M.O. 1999, "The size and shape of Kilauea Volcano’s summit magma storage reservoir: A geochemical probe", Earth and Planetary Science Letters, vol. 167, no. 3-4, pp. 311-320.

Skilling, I. & McGarvie, D. 2018, "Kilauea, Hawai'i, puts on a 'once-in-a-century' show", Geology Today, vol. 34, no. 4, pp. 155-160.