How Often Do Volcanoes Erupt In Hawaii?

Hawaii is known as the island paradise, but the volcanic activity that created its majestic landscapes poses an ever-present threat. If you’ve wondered about the frequency of volcanic eruptions in Hawaii that have shaped its world-famous beaches and turquoise waters through fire and magma over millions of years, read on.

If you’re short on time, here’s a quick answer to your question: On average, Hawaiian volcanoes erupt every 3-5 years, with more significant eruptions occurring every few decades. The volcanoes on Hawaii’s Big Island are the most active.

In this comprehensive guide, we will explore the geology that produces Hawaii’s volcanoes and drives their eruptions over time. You’ll learn about the different types of eruptions, historical eruption data, current activity levels on the Big Island, and how scientists forecast future eruptions.

Hawaii’s Unique Geology and Hotspot Volcanism

Plate Tectonics Over Hotspots

The Hawaiian islands were formed by a hotspot deep underground in the mantle layer. As the Pacific tectonic plate moves northwestward over this hotspot at about 32 miles per million years, volcanoes form over the hotspot, grow as islands while active, then become extinct and erode as they move away from the hotspot (USGS).

This explains why the islands get progressively older to the northwest.

The hotspot under Hawaii is over 1,800 miles deep and provides a continuous source of magma from the mantle. The unique geology of Hawaii makes it one of the most actively erupting places on Earth. The movement of the Pacific plate over this deep and fixed hotspot is also responsible for the southeast orientation of most Hawaiian volcanoes and rift zones along which eruptions occur.

Frequent Eruptions and Active Volcanoes

With the hotspot fueled by magma from deep within the mantle, the Hawaiian volcanic chain averages nearly one eruption every year, spread across all active volcanoes. For example, Kīlauea volcano has been near-continuously active since 1983, with over 60 eruptions in 40 years (USGS-HVO)!

Of the five volcanoes that make up Hawaii island, three are considered active – Kīlauea, Mauna Loa, and Hualālai. Lōʻihi beneath the water and Haleakalā volcano on Maui may erupt again as well. Amazingly, nearly 80% of the total surface area of the islands is made of volcanic flows less than 10,000 years old.

The frequent volcanic activity here contributes to incredible biodiversity and landscapes seen nowhere else on Earth.

Eruption Types and Cycles in Hawaii

Effusive Basalt Eruptions

The majority of eruptions in Hawaii are effusive basalt eruptions, where fluid lava flows out of fissures or vents at a relatively non-explosive pace. This allows the lava to flow in rivers across the land over periods lasting from hours to months or even years.

The high frequency but low intensity of these eruptions builds up the Hawaiian islands over time. The lava flows can cause damage, but generally move slow enough for evacuation.

Explosive Eruptions

More rarely, Hawaiian volcanoes can have brief explosive eruptions, usually at the start of an effusive eruption as gases trapped in the magma burst out. These can shoot rock fragments kilometers into the air and dust areas with a layer of ash.

But sustained explosive activity is very uncommon, as the fluid basalt lava of Hawaii usually allows gases to escape passively.

Eruption Frequency and Significant Events

Looking at the past 200 years of records, Hawaiian volcanoes erupt on average every 5 years or less, though a volcano can remain dormant for longer periods. The year with the most volcanic events in Hawaii was 1984, which saw eruptions start at both Mauna Loa and Kilauea volcanoes.

Since 1952, Kilauea has erupted 34 times, with eruptions typically lasting months to years with occasional pauses. This makes it one of the world’s most active volcanoes.

Tracking Cyclic Activity

The Hawaiian Volcano Observatory closely monitors earthquake activity, ground deformation, and gas emissions at active volcanoes, to track underground magma movement and forecast coming eruptions. This allows them to issue warnings when an eruption begins.

They’ve also studied past eruption records and found that each volcano has its own eruption patterns – Mauna Loa erupts every 3 to 8 years, while Kilauea has shorter 1 to 3 year cycles. Tracking these cycles along with monitoring helps assess risk of future activity.

Historic Eruption Timelines and Accounts

Pre-Contact Eruptions

The Hawaiian Islands were formed by a hot spot in Earth’s mantle over millions of years. As the Pacific tectonic plate has drifted northwest, volcanoes have erupted over this hot spot and created new islands.

Scientists estimate the oldest Hawaiian Island, Kure Atoll, began forming around 30 million years ago.

Of course, human written records only date back thousands of years. Oral histories and legends provide some of the only glimpses into ancient eruptions before European contact in the 18th century.

Ancient Hawaiians told stories of Pele, the volatile goddess of volcanoes. The legends describe destructive lava flows and ash clouds shrouding the islands after an angered Pele erupted from Kīlauea or other volcanoes.

While exaggerated, core elements of these stories seem to describe actual historic eruptions.

Documented Modern Eruptions

The first written account of a Hawaiian eruption comes from British explorer James King in 1779, who documented an eruption of Kīlauea with fissures spewing molten rock. Since 1823, there have been over 50 recorded eruptions in Hawaii.

Kīlauea is Hawaii’s most active volcano – with 34 eruptions since 1823. Mauna Loa ranks second in activity, followed by Hualālai and Haleakalā volcanoes on Maui. Kīlauea and Mauna Loa often erupt simultaneously from different rift zones along their slopes.

Kīlauea’s most destructive modern eruption was in 2018, with lava flows covering over 35 square miles. This event destroyed over 700 homes but thankfully did not cause any deaths. Scientists monitor seismic activity and ground swelling to forecast future eruptions.

To learn more, visit the USGS Hawaiian Volcano Observatory.

Current Status and Monitoring of Active Volcanoes

Kīlauea – Active and Closely Observed

The Kīlauea volcano on Hawaii’s Big Island has been closely monitored by scientists for decades. Kīlauea has been persistently active since 1983, with lava flows occurring continuously for over 30 years until 2018.

In May 2018, increased seismic activity and summit collapse heralded dramatic changes, with massive lava eruptions in the Lower East Rift Zone. While activity has calmed since then, with only a lava lake visible in Halema‘uma‘u crater, Kīlauea remains an active volcano.

The USGS Hawaiian Volcano Observatory (HVO) closely tracks and studies Kīlauea through seismometers, GPS, webcams, gas measurements, and field observations. They produce weekly updates and timely warnings when conditions change. Satellite radar data also tracks ground deformation due to moving magma.

Thanks to this extensive monitoring, scientists can usually predict eruptions days to weeks in advance to help authorities plan.

Monitoring Mauna Loa and Beyond

The Mauna Loa volcano last erupted in 1984, but inflation indicates it is awakening from its “slumber”. HVO monitors Mauna Loa with over 70 seismic stations, GPS, webcams, and satellite data. Interestingly, patterns show a correlation between Mauna Loa and Kīlauea eruptions throughout history.

When one volcano erupts, it seems to transfer pressure to the other. Scientists are studying this connection.

Beyond Hawaii’s five main volcanoes, HVO runs the only CO2 monitoring network on the planet, tracking diffuse volcanic emissions. They also monitor submarine volcanoes like Lō‘ihi, still developing on the ocean floor.

Data is shared freely online at https://www.usgs.gov/observatories/hawaiian-volcano-observatory. HVO’s tireless monitoring and research is advancing global understanding of volcano behavior.

Forecasting the Next Hawaiian Eruption

Predicting Cycles and Types of Activity

Hawaiian volcanoes like Kilauea and Mauna Loa erupt on a semi-regular basis, going through cycles of activity and dormancy that can last from months to decades. Geologists use several methods to forecast when the next eruption may occur:

• Monitoring ground deformation – as magma accumulates, the ground swells and tilts, providing clues about pressure building underneath
• Tracking earthquake activity – more small earthquakes suggest magma is on the move
• Measuring gas emissions from the volcano – increased sulfur dioxide levels signal rising magma

In addition, each Hawaiian volcano has distinctive patterns. For example, Kilauea has erupted 63 times since 1952, roughly every 3-5 years. Mauna Loa erupts less often, but tends to produce large and lengthy eruptions after long repose periods.

Using past activity as a guide, scientists make educated guesses about what type of event could happen next.

Preparedness and Hazard Mitigation

While exact eruption forecasts are rarely possible, Hawaiian authorities use volcanology research to prepare contingency plans and educate the public. Strategies include:

• Mapping lava flow hazard zones to guide emergency responses and development
• Installing monitoring equipment like tiltmeters and webcams to provide early warning
• Holding community readiness workshops for residents near volcanoes
• Establishing protocols for aviation alerts, evacuations, and relief efforts

Ongoing volcano research also informs long-term hazard mitigation. For example, the USGS Hawaiian Volcano Observatory’s analyses help determine optimal locations for critical infrastructure to limit volcanic risks when the next eruption occurs.

Conclusion

To conclude, the unique geology of Hawaii makes volcanic eruptions an integral part of these precious islands. Expect spectacular fire shows averaging every 3-5 years, with more significant lava-producing events every couple decades that add land and reshape landscapes.

Advanced monitoring and predictive models empower preparation over fear regarding Hawaiian volcanic activity into the future. While eruptions pose risks, they thread beauty and life through Hawaii’s history.

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