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Hawaii’s volcanoes have captured the imagination for centuries. Their destructive power is formidable, but what exactly would happen if one of Hawaii’s volcanoes erupted today? Let’s take a closer look.

If you’re short on time, here’s a quick answer to your question: A major volcanic eruption in Hawaii could cause ashfall across the islands, damage to infrastructure, disruptions to air travel, and more. The extent of the damage would depend on factors like the type of eruption, location, and precautionary measures taken by authorities.

In this comprehensive article, we will explore the science behind Hawaii’s volcanoes, past eruptions and their impacts, the monitoring systems in place today, the most likely effects of a future eruption, and steps residents and visitors can take to stay safe if the worst should happen.

The Volcanic Origins of the Hawaiian Islands

The Hawaiian Islands are a remarkable archipelago located in the Pacific Ocean. What makes them even more fascinating is their volcanic origins. These beautiful islands were not formed by tectonic activity or the collision of continental plates like other landmasses. Instead, they owe their existence to a series of volcanic eruptions that occurred millions of years ago.

How the Islands Formed

The formation of the Hawaiian Islands is a result of the movement of the Pacific tectonic plate over a hotspot in the Earth’s mantle. This hotspot is a region of intense heat and volcanic activity beneath the Earth’s surface. As the tectonic plate moves slowly over this hotspot, magma rises to the surface, creating volcanic eruptions and forming new landmasses.

Over time, these repeated eruptions formed a chain of islands, with each island corresponding to a different stage in the volcanic process. The oldest and most eroded islands are located to the northwest, while the youngest and most active ones are found to the southeast. This unique geological process has given rise to the breathtaking landscapes and diverse ecosystems that make Hawaii such a popular destination.

The Hotspot Theory

The hotspot theory is the prevailing explanation for the formation of the Hawaiian Islands. According to this theory, a stationary hotspot beneath the Pacific tectonic plate has been producing magma for millions of years, creating a chain of volcanic islands. The movement of the tectonic plate over the hotspot is what has caused the islands to form in a linear pattern.

While the hotspot itself remains in the same location, the tectonic plate continues to move, resulting in the formation of new islands. This theory is supported by various geological evidence, including the age progression of the islands, with the youngest islands being the most volcanically active.

If you want to learn more about the volcanic origins of the Hawaiian Islands, you can visit the National Park Service website, where you will find detailed information about the geology and volcanic activity of Hawaii’s volcanoes.

Characteristics of Hawaiian Volcanoes and Eruptions

Shield Volcanoes

Hawaii is home to some of the most famous shield volcanoes in the world. These volcanoes, including Mauna Loa and Kilauea, have gently sloping sides and are characterized by their broad, dome-like shape resembling a warrior’s shield. Unlike explosive stratovolcanoes, shield volcanoes typically have non-explosive eruptions, with lava flowing steadily from the central vent. This is due to the low viscosity of the basaltic lava, allowing it to travel long distances before solidifying.

Shield volcanoes have a long history of volcanic activity, with eruptions occurring frequently over thousands of years. The continuous eruption of Kilauea, for example, has been ongoing since 1983, making it one of the most active volcanoes on Earth. Despite their relatively non-explosive nature, these volcanoes can still pose risks to nearby communities due to the potential for lava flows and gas emissions.

Lava Flows

One of the primary hazards associated with Hawaiian volcanoes is the threat of lava flows. These streams of molten rock can travel at varying speeds, depending on the viscosity of the lava and the slope of the terrain. In Hawaii, lava flows commonly move slowly, allowing residents and authorities to monitor and respond to the advancing flow.

However, there have been instances when lava flows have threatened communities and infrastructure. In 2018, for example, the eruption of Kilauea resulted in the destruction of hundreds of homes and forced the evacuation of thousands of residents. Despite the potential dangers, the slow-moving nature of Hawaiian lava flows often allows for safe evacuation and minimal loss of life.

Pyroclastic Flows and Ashfall

While shield volcanoes in Hawaii are known for their predominantly non-explosive eruptions, there are instances when explosive activity can occur. During these explosive events, pyroclastic flows and ashfall become significant hazards.

Pyroclastic flows are fast-moving currents of hot gas, ash, and volcanic material that can travel down the slopes of a volcano at speeds of over 100 kilometers per hour. These flows can be deadly, incinerating everything in their path and causing widespread devastation. Ashfall, on the other hand, occurs when fine particles of volcanic ash are ejected into the atmosphere and carried by wind currents. Ashfall can have serious impacts on air quality, infrastructure, and agriculture.

It is important for residents and visitors in Hawaii to stay informed about volcanic activity and be prepared for potential eruptions. The Hawaiian Volcano Observatory, operated by the United States Geological Survey, provides up-to-date information and monitoring of volcanic activity in the region. By staying informed and following the guidance of authorities, individuals can minimize the risks associated with volcanic eruptions in Hawaii.

Monitoring Hawaii’s Active Volcanoes

Monitoring the activity of Hawaii’s active volcanoes is crucial for the safety and well-being of the local population and the surrounding areas. Scientists and experts utilize various tools and techniques to keep a close eye on the volcanic activity and detect any signs of potential eruptions. These monitoring efforts involve the use of seismic sensors, gas emissions analysis, ground deformation measurements, and the observation of webcams and satellite images.

Seismic Sensors

Seismic sensors are strategically placed around active volcanoes in Hawaii to detect and measure any seismic activity. These sensors are designed to detect even the slightest vibrations or tremors that may indicate volcanic unrest. By analyzing the data collected from these sensors, scientists can gain valuable insights into the behavior of the volcano and identify any changes that may suggest an impending eruption. This information is crucial in issuing timely warnings and implementing evacuation measures to ensure the safety of the local population.

Gas Emissions

Gas emissions from volcanoes can provide valuable information about the state of volcanic activity. By analyzing the composition and quantity of gases released by the volcano, scientists can gain insights into the underlying processes occurring within the volcano. Monitoring equipment, such as gas analyzers and spectrometers, are used to measure the gas emissions and track any changes over time. This data can help scientists assess the level of volcanic activity and anticipate potential eruptions.

Ground Deformation

Volcanic activity can cause the ground to deform, either by swelling or subsiding, as magma moves beneath the surface. Ground deformation monitoring involves the use of GPS receivers and satellite-based radar systems to measure these changes with great precision. By monitoring ground deformation, scientists can track the movement of magma and identify areas of increased volcanic activity. This information is crucial for determining the potential risks associated with an eruption and informing evacuation plans.

Webcams and Satellite Images

Webcams and satellite images provide real-time visual monitoring of volcanic activity. High-resolution cameras positioned near the active volcanoes capture images that are continuously streamed online, allowing scientists and the public to observe the volcano’s behavior. Satellite images, on the other hand, provide a broader perspective and can help identify changes in the volcanic landscape, such as new lava flows or the formation of new vents. These visual monitoring tools are essential for tracking the progression of volcanic eruptions and assessing their potential impact on the surrounding areas.

Monitoring Hawaii’s active volcanoes through the use of seismic sensors, gas emissions analysis, ground deformation measurements, and visual observation tools like webcams and satellite images is crucial for predicting and mitigating the risks associated with volcanic eruptions. By continuously monitoring these volcanoes, scientists can provide timely warnings and take necessary measures to ensure the safety of the local population and minimize the potential impact of volcanic activity.

Impacts of Past Eruptions in Hawaii

Kīlauea 2018 Eruption

The Kīlauea volcano eruption in 2018 was one of the most significant volcanic events in recent history. It began on May 3rd with the collapse of the Puʻu ʻŌʻō vent, leading to a series of powerful lava flows and explosive eruptions. The eruption lasted for over three months, impacting communities and the environment in various ways.

The most immediate impact was the destruction of homes and infrastructure. Lava flows consumed entire neighborhoods, displacing thousands of residents. The eruption also caused closures of popular tourist attractions, such as Hawai’i Volcanoes National Park, leading to economic losses for the local tourism industry.

Furthermore, the release of toxic gases, such as sulfur dioxide, posed serious health risks for people living near the volcano. The poor air quality resulted in respiratory problems and forced evacuations from affected areas. The eruption also had ecological consequences, including the destruction of vegetation and the alteration of natural habitats.

Mauna Loa 1950 Eruption

The Mauna Loa eruption in 1950 was the largest eruption on the island of Hawai’i in the 20th century. It began on June 22nd and lasted for 23 days, producing extensive lava flows that threatened nearby communities.

The primary impact of the eruption was the destruction of property and infrastructure. Lava flows reached the outskirts of the town of Hilo, causing evacuations and damage to homes and businesses. Fortunately, due to early warnings and evacuation efforts, there were no fatalities during this eruption.

The eruption also had indirect impacts on agriculture and the economy. Ashfall from the eruption affected crops and livestock, leading to losses for local farmers. The closure of roads and disruption of transportation networks further hindered economic activities.

Hualālai 1800s Eruptions

Hualālai volcano, located on the western side of the Big Island, has experienced several eruptions in the 1800s. These eruptions had significant impacts on the surrounding areas, including the destruction of villages and disruption of daily life.

One notable eruption occurred in 1800, when lava flows reached the coast, destroying fishing villages and covering valuable agricultural land. Another eruption in 1832 caused similar destruction, displacing communities and disrupting food production.

These eruptions serve as a reminder of the long-term effects that volcanic activity can have on human settlements. They highlight the importance of monitoring and preparedness to mitigate the impacts of future eruptions.

Most Likely Effects of a Future Eruption


One of the most immediate and widespread effects of a volcanic eruption in Hawaii is ashfall. When a volcano erupts, it releases a mixture of gases, ash, and rock fragments into the air. The ash can travel long distances and settle on the ground, creating a layer of fine particles. This ashfall can have a range of impacts, from mild inconveniences such as dirty cars and reduced visibility to more serious health hazards. Breathing in volcanic ash can irritate the respiratory system and cause respiratory issues, especially for people with pre-existing conditions like asthma or bronchitis.

In the event of an eruption, it is important to stay indoors and avoid unnecessary exposure to ashfall. Close windows and doors, use air purifiers if available, and wear masks if you need to go outside.

Lava Flow Damage

Another major effect of a volcanic eruption in Hawaii is the damage caused by lava flows. When a volcano erupts, molten lava can flow down its slopes, destroying everything in its path. Lava flows can be slow-moving or fast-moving, depending on the type of lava and the steepness of the terrain. They can engulf houses, roads, and vegetation, causing significant property damage and displacing communities.

If you live in an area that is prone to lava flows, it is important to be prepared and have an evacuation plan in place. Stay informed about the latest updates from local authorities and follow their instructions in case of an eruption. Remember that property can be replaced, but your safety and the safety of your loved ones should always be the top priority.

Volcanic Smog

Volcanic smog, also known as vog, is a phenomenon that occurs when volcanic gases react with sunlight, oxygen, and other gases in the atmosphere. This creates a haze of pollutants that can have detrimental effects on human health. Vog contains sulfur dioxide, which can cause respiratory issues, eye irritation, and other health problems.

During a volcanic eruption, the concentration of vog in the air can increase significantly, especially in areas downwind of the volcano. People with respiratory conditions, such as asthma or chronic obstructive pulmonary disease (COPD), may experience worsening symptoms. It is important to stay informed about air quality conditions and take necessary precautions, such as staying indoors and using air purifiers, if vog levels are high.

Disruptions to Air Travel

When a volcano erupts, it can release ash particles into the atmosphere that can pose a significant risk to aircraft. Volcanic ash can damage aircraft engines and other critical parts, leading to engine failure or reduced performance. As a result, airspace around the volcano may be closed, and flights may be canceled or diverted to avoid volcanic ash clouds.

Airports in the vicinity of the eruption may experience disruptions, with delays and cancellations affecting both domestic and international flights. Passengers should stay in touch with their airlines for updates and follow any instructions given by airport authorities. It is important to prioritize safety over convenience in such situations.

Staying Safe in the Event of an Eruption

Have an Evacuation Plan

In the event of a volcanic eruption in Hawaii, it is crucial to have a well-prepared evacuation plan in place. Familiarize yourself with evacuation routes and shelters in your area. Discuss the plan with your family members or housemates so that everyone knows what steps to take and where to meet in case you are separated. It is also important to have a designated person to contact outside the affected area, so they can keep track of your safety and well-being.

Prepare Emergency Supplies

When a volcano erupts, it can disrupt essential services such as electricity, water, and transportation. It is essential to have emergency supplies ready to sustain you and your loved ones for at least 72 hours. These supplies should include non-perishable food, drinking water, medications, a first aid kit, flashlights, batteries, a battery-powered radio, and extra clothing. Don’t forget to include important documents such as identification papers, insurance policies, and contact information.

Listen to Authorities

During a volcanic eruption, it is crucial to stay informed and follow the instructions given by local authorities. They have the necessary expertise and resources to assess the situation and make decisions that prioritize your safety. Monitor local news outlets, radio broadcasts, or official websites for updates and instructions. Authorities may issue evacuation orders or provide information on areas to avoid due to the dangers posed by volcanic activity. Following their guidance will help ensure your safety.

Protect Against Ashfall

When a volcano erupts, it releases ash into the atmosphere, which can pose health risks and cause damage to infrastructure. If you find yourself in an area affected by ashfall, take precautions to protect yourself. Stay indoors as much as possible and keep windows and doors closed to prevent ash from entering your home. Use damp towels or masks to cover your nose and mouth when you need to go outside. Avoid driving as ash can reduce visibility and damage vehicle engines. Clean ash from roofs, gutters, and outdoor surfaces to prevent structural damage.

Remember, volcanoes are natural wonders that can be unpredictable. Being prepared and knowing what to do in the event of an eruption is essential for your safety and the safety of those around you. Stay informed, have a plan, and be ready to adapt as the situation unfolds.


Hawaii’s volcanoes are complex, awe-inspiring forces of nature. While eruptions can certainly wreak havoc, understanding volcanic hazards allows us to prepare and minimize risks. With proper monitoring and safety precautions, the people of Hawaii can skillfully coexist with these iconic peaks. Their rumbles serve as reminders that our Earth is a dynamic, living planet.

Though the timing of the next eruption is unknown, this guide equips you with knowledge about what could happen and how to stay safe. The best plan is to remain vigilant, follow expert advice, and appreciate the volcanoes’ grandeur from a respectful distance.

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