Buzz
As of December 10, Mauna Loa’s fissure 3 seems to have calmed, with the lava fountains now replaced by a steady lava lake. This shift in activity has been carefully documented by J. Bard/USGS since the eruption began on November 27, 2022.Volcanoes, while awe-inspiring and magnificent, pose great risks, as demonstrated by the ongoing eruptions of Kilauea and Mauna Loa on Hawaii's Big Island. Kilauea's eruption in 2018 resulted in the destruction of over 700 homes in the Leilani Estates and Kapoho areas.
The proximity of Mauna Loa and Kilauea is alarming, with just 21 miles (33 kilometers) separating the two giants. Not since 1984, when Mauna Loa last erupted, have these two volcanoes erupted simultaneously.
Although neither of the volcanoes poses a direct threat to homes, the lava flow from Mauna Loa came dangerously close to Daniel K. Inouye Highway (Saddle Road) on December 11, less than 2 miles away, as reported by the U.S. Geological Survey (USGS).
As a scientist specializing in volcanoes, I am acutely aware of the deadly potential of volcanic eruptions, including those that are 'nonexplosive' like the one we witnessed in Hawaii last November. Since the year 1500, volcanic eruptions have claimed the lives of more than 278,000 people.
Around the globe, there are currently 1,350 volcanoes considered potentially active. Each year, approximately 75 of them erupt, and roughly 800 million people live in areas vulnerable to volcanic risks. Volcanologists play a key role in studying and monitoring these natural phenomena to forecast future eruptions and assess the potential extent of their damage.
When Volcanic Mountains Explode
Volcanic eruptions can be categorized into two primary types: explosive and nonexplosive. Explosive eruptions happen when magma, the molten rock beneath the Earth's surface, contains gas. These eruptions are so forceful that the magma is broken down into fine particles known as volcanic ash.
Explosive eruptions are responsible for the highest number of volcanic-related fatalities. These powerful events can spread volcanic ash for hundreds of miles, leading to significant disruptions in air travel, contamination of water supplies, and extensive damage to power lines, infrastructure, and machinery. Notable examples include the 1883 eruption of Krakatoa in the Pacific and Mount St. Helens in Washington state in 1980. While Kilauea and Mauna Loa eruptions are typically non-explosive, both volcanoes have experienced explosive eruptions in the past.
The most perilous aspect of explosive eruptions is the volcanic ash flow — a fast-moving, ground-hugging avalanche of searing gas, ash, and rock that obliterates everything in its path. Ash flows from the 79 A.D. eruption of Mount Vesuvius in Italy buried the cities of Herculaneum and Pompeii. In 1902, the eruption of Mount Pelée on the Caribbean island of Martinique produced ash flows that claimed over 29,000 lives. A similar eruption of Kilauea in 1790 resulted in the deaths of approximately 80 people.
The eruption of Soufriere Hills on Montserrat in November 2009 was extremely violent. The image shows light gray steam and minor ash rising from the volcano's summit on the left, while a darker gray cloud of hazardous pyroclastic flow descends the volcano's flank on the right.
Johnathan Stone/USGSLava Flows and Fountains
Nonexplosive eruptions happen when the magma contains little to no gas. These eruptions typically produce small fire fountains and lava flows, such as those seen erupting from Kilauea and Mauna Loa.
Although nonexplosive eruptions are generally less deadly than explosive ones, they can still lead to significant disruption and damage. Eruptions from Hawaiian-style volcanoes can occur either at the summit or along the flanks. New eruptions usually start with the opening of a fissure or crack that releases molten lava into the air, sometimes forming lava flows.
Lava tends to move at a slow pace. While it is generally possible to outrun a lava flow, it is impossible to stop or divert it. People can escape, but homes and properties remain at risk.
Both explosive and nonexplosive eruptions release volcanic gases, which create a dangerous phenomenon known as volcanic fog, or VOG. VOG contains fine particles formed when sulfur dioxide combines with moisture in the air. This can lead to health issues, crop damage, and pollution of water supplies. In November, the health department warned that air quality around Mauna Loa would decline due to hazards such as VOG.
These particles can have global effects when they are propelled into the stratosphere, where they block sunlight, resulting in a cooling of Earth's climate. This can cause widespread crop failures and famines, contributing to many historical volcanic-related fatalities. For instance, the explosive eruption of Tambora in Indonesia in 1815 led to 92,000 deaths due to starvation.
Snow-capped volcanoes, like those found in the Cascades and Alaska, can generate mudflows, also known as lahars. These dangerous events occur when ice and snow melt during an eruption, or when heavy rainfall washes ash from the volcano's surface.
Mudflows are incredibly powerful and can travel up to 60 miles per hour down river valleys. They have the potential to destroy bridges, buildings, and anything else in their path. A mudflow caused by the 1985 eruption of Nevado del Ruiz in Colombia claimed the lives of 25,000 people.
This telephoto image of the lava lake inside Kilauea's Halema'uma'u crater, taken on November 23, 2022, illustrates that while the volcano isn't actively ejecting lava, it continues to release toxic gases into the atmosphere.
K. Mulliken/USGSPreparing for the Next Volcanic Eruption
By examining both historical and contemporary eruptions, volcanologists are continually enhancing their ability to forecast and manage the risks associated with volcanic activity. However, individuals living in areas prone to volcanic hazards can also take steps to reduce their risk.
All residents in these regions should establish evacuation or shelter-in-place plans for their households and assemble emergency kits containing first aid items, essential medications, food, and water. Events such as the Kilauea eruption serve as powerful reminders that proactive disaster preparation strengthens a community's resilience when disaster strikes.
Brittany Brand is an associate professor of geosciences at Boise State University, where she also serves as the director of the Boise State Hazard and Climate Resilience Institute. Her research focuses on eruption dynamics, sediment transport in volcanic flows, and volcanic hazard assessment.
This article is an update of a story first published on The Conversation under a Creative Commons license. You can find the original article here.
