A Giant Awakens: The Mauna Loa Eruption
The Mauna Loa Eruption. Source: University of Miami.
The Mauna Loa volcano on the Big Island of Hawaii erupted around midnight on Sunday, November 27th for the first time in 38 years. The once-sleeping giant is the largest active volcano in the world, covering over half of the island with an area of over 1,900 square miles. Despite being the largest, Mauna Loa may not appear like the typical mountain-peak image associated with volcanoes; it is a shield volcano, consisting of shorter peaks that resemble hills, and a wide spread. At the top of the summit is the caldera, a large depression where magma once collected.
Scientists were able to predict an eruption as early as September while monitoring the volcano’s earthquakes. Typically, Mauna Loa experiences 10 to 20 earthquakes daily. As new magma flows began to increase into the main reservoir, the reservoir considerably expanded, causing an increase in seismic activity with reports of 40 to 50 daily earthquakes occurring northwest of Mauna Loa’s caldera. Despite knowing that an eruption was due soon, one question remained for scientists that would determine if an emergency would play out on the Big Island once it all began where would the lava flow?
Two rifts sit on either side of the volcano, formed by cooled magma from previous eruptions. The southwest rift flows into Kona’s residential areas, while the northeast end flows to an unoccupied area of the island. Once the eruption began, aerial surveillance observed that the magma quickly filled the caldera and eventually poured out into the northeast, meaning surrounding communities were safe from direct destruction.
The Mauna Loa Eruption. Source: National Park Service.
Although the lava is currently flowing northeast, residents have been asked to reevaluate their safety plans as flows can be unpredictable and continue to move closer to Saddle Road, a route taken for cross-island travel. Secondary concerns in the form of health hazards have also dictated local news announcements, as residents and visitors—especially sensitive groups—have been advised to limit outdoor activities due to decreased air quality from the eruption. Airborne ash, sulfur dioxide, and vog—a cocktail of toxic gasses emitted during the eruption—are all corrosive substances that can lead to or worsen respiratory issues, such as asthma, bronchitis, and chronic lung diseases, especially in children and the elderly. Although air quality remains normal for most of the island, local health departments warn that conditions can change expeditiously.
Another public health hazard that has arisen in the near two-week eruption is the emergence of Pele’s Hair. At first glance, they look like strands of golden-blonde hair, utterly harmless to humans. However, Pele’s Hair is the byproduct of bursting bubbles of hot lava that are stretched to form long glass-like strands spanning several feet long but are only as thin as a piece of human hair. Hawaiian officials have issued warnings to surrounding communities that Pele’s Hair can easily be picked up by wind and become lodged within one’s hair, skin, or eyes, increasing the risk of skin abrasions or eye piercings, especially in downwind communities.
Pele's hair. Source: National Park Service.
Mauna Loa’s 38-year rest brought much more than new magma to the surface; the safety situation remains precarious as environmental health hazards have formed as a direct result of the eruption. However, with new eruptions comes new knowledge about these massive elemental forces, allowing local volcanologists to learn new ways to predict activity and safeguard life on the Big Island. Cautious intrigue has captured the attention of scientists and civilians alike, as this once-in-a-lifetime show of nature continues to gather spectators around the world.
