How Much Of Hawaii Is Affected By Volcanoes?

The Hawaiian Islands are well known for their active volcanoes that frequently erupt lava flows across the landscape. If you want a quick answer, less than 25% of Hawaii’s total land area has been covered by lava flows in the past 10,000 years from the 5 active volcanoes on the islands.

In this comprehensive guide, we will explore the volcanic origins of the Hawaiian islands, examine the active volcanoes spewing lava across parts of the islands, analyze what percentage of the different islands’ land area has been affected by volcanic activity, and assess the ongoing impacts volcanic eruptions have on infrastructure, residents, and tourists.

The Volcanic Origins of Hawaii

How the Hawaiian Island Chain Formed

The Hawaiian Islands were created by a geological hot spot under the Pacific Plate. As the plate moves slowly northwestward over the hot spot at about 32 miles per million years, volcanoes begin forming over the hot spot. With each newly formed volcano, a new island is created in the chain.

The island chain stretches over 1,500 miles across the northern Pacific Ocean.

The hot spot under the plate is a plume of hot solid rock from deep inside the Earth’s mantle. It is stationary relative to the moving plate above it. The hot spot partially melts the oceanic crust above it, becoming less dense and more buoyant than the surrounding rock.

This creates uplift and weaknesses in the crust where magma can break through to the surface, creating a volcano.

The Big Island of Hawaii is where the hot spot currently sits, making its volcanoes the most active. As the plate moves on, the islands move off the hot spot, stop receiving new lava, and slowly sink back into the sea as they erode.

This is why the islands become progressively older as you move northwest along the chain away from the Big Island.

Types of Volcanoes in Hawaii

There are two main types of volcanoes in Hawaii: shield volcanoes and cinder cone volcanoes:

• Shield volcanoes – These broad, gently sloping volcanoes are created by highly fluid basaltic lava flows during long eruptions. The flows can travel many miles from their vents. Hawaii’s famous volcanoes like Mauna Loa and Kilauea are shield volcanoes.

  Over 90% of Hawaii’s surface area consists of shield volcano lava flows.

• Cinder cone volcanoes – These are smaller, steep conical hills formed by ejected fragments of lava and volcanic ash. They are created during explosive eruptions and short-lived than shield volcanoes. Cinder cones are usually found flanking larger shield volcanoes.

In addition, when oceanic volcanoes grow too massive, their sheer weight can cause landslides leading to debris avalanches. These underwater landslides are common events in Hawaii, with over 70 identified so far.

The flank collapse at Hilina Pali on the Big Island was one of the largest in history at over 250 cubic miles.

To learn more about the different volcanoes and volcanic features across the islands, check out the USGS Hawaiian Volcano Observatory’s volcano guide.

Hawaii’s Active Volcanoes

Kilauea – Hawaii’s Most Active Volcano

Kilauea, located on Hawaii’s Big Island, is one of the world’s most active volcanoes. According to the United States Geological Survey (USGS), Kilauea has erupted 67 times since 1823. Its most recent eruption began in 1983 and lasted for over 35 years, making it one of the longest-lived eruptions in recent history.

Kilauea erupts frequently due to its location over a hot spot in Earth’s mantle. Magma rises through cracks and weak areas in the crust, feeding lava flows and opening new vents. Historic eruptions have produced spectacular lava fountains, thick fluid pāhoehoe flows, and dangerous ash plumes.

Today, Kilauea affects residents and visitors to Hawaii Volcanoes National Park. Over 200 homes have been destroyed by lava flows in recent decades. At the same time, the volcano has added nearly 500 acres of new land to Hawaii’s coast through continuous eruptions.

Kilauea remains closely monitored for signs of unrest by USGS Hawaiian Volcano Observatory.

Mauna Loa – Earth’s Largest Volcano

Mauna Loa, world’s largest active volcano by volume, covers over half of Hawaii’s Big Island. According to the USGS, Mauna Loa has erupted 33 times since 1843, with eruptions lasting between a few hours to several weeks.

Despite its size and frequent activity, Mauna Loa’s eruptions rarely threaten communities. Most lava flows follow predictable paths down the volcano’s gently sloping flanks. However, Mauna Loa presents other hazards like volcanic earthquakes, ground cracking and hazardous ash fallout that have affected island residents in the past.

Mauna Loa remains hazardous, with increased seismicity recorded under its summit in recent years. The USGS estimates a 37% chance of Mauna Loa erupting before 2043. When it roars to life again, it may affect air traffic and parts of Hawaii Volcanoes National Park popular among tourists.

Hualalai and Haleakala Volcanoes

Though less active than Mauna Loa and Kilauea in modern times, Hualalai and Haleakala volcanoes have impacted Hawaii residents dramatically in history. According to the USGS, Hualalai volcano on Hawaii’s Big Island last erupted in 1801.

Its lava flows threatened the town of Kailua Kona but were diverted by offerings, sparing it from destruction according to native Hawaiian oral tradition.

Haleakala volcano, which formed east Maui island, last erupted around 1790 CE according to USGS records. These eruptions built up large cinder cones near present-day residential areas. Though Haleakala is less likely to erupt today, its scenic summit crater still draws over 1.5 million visitors to Haleakala National Park each year.

Though less active today, Hualalai and Haleakala serve as reminders of how even dormant-looking Hawaiian volcanoes can awaken and alter the landscape. Continued monitoring by USGS and emergency preparedness are crucial to limit threats from future eruptions.

Percentage of Hawaii Affected by Lava Flows

Big Island Lava Coverage

The Big Island of Hawaii, also known as Hawaii Island, has endured numerous lava flows over its history due to the presence of five active volcanoes. According to the U.S. Geological Survey (USGS), around 20% of Hawaii Island’s total land area has been covered by lava flows in the past 200 years alone.

The volcanoes Mauna Loa and Kilauea have been the most active, contributing over 50% of the island’s surface area.

Kilauea volcano’s East Rift Zone has produced some of the most destructive lava events, like the 2018 lower Puna eruption that covered over 13 square miles of land and 700 homes. However, other parts of the island have also endured impact.

For example, an 1868 eruption sent lava flowing from Mauna Loa volcano towards Hilo, destroying crops and villages. Today, nearly 50% of Hawaii Island is estimated to consist of lava less than 1,000 years old.

Maui and Oahu Lava Impacts

The islands of Maui and Oahu have experienced less volcanic activity than the Big Island. Maui’s Haleakalā volcano last erupted sometime between 1480 and 1600 CE. On Oahu, the Honolulu Volcanic Series produced volcanic cones like Punchbowl Crater and Diamond Head over one million years ago.

However, lava flows covered large parts of these islands long ago.

It’s estimated around 25% of Maui Island’s surface consists of lava flows from Haleakalā. Some flows extended all the way to the ocean, creating striking landscapes like La Perouse Bay. Oahu has less visible lava coverage at around 5-10%, but remnants still shape the landscape.

For instance, the Koolau Range formed from eruptions of the Koʻolau Volcano 2.5 million years ago.

So while volcanism shaped these Hawaiian islands, the Big Island endures the most active changes. Over 90% of Hawaii’s land covered by fresh lava exists on Hawaii Island. Residents here live with an ever-transforming environment courtesy of the world’s most active volcanoes.

Ongoing Impacts of Hawaii’s Volcanoes

Infrastructure Damage from Lava and Ash

Hawaii’s active volcanoes pose a constant threat to infrastructure across parts of the islands. When eruptions occur, lava, volcanic ash and gases can damage or destroy roads, homes, businesses, utility lines and agriculture.

For example, the 2018 lower Puna eruption of Kīlauea volcano covered over 13 square miles, destroying over 700 structures and dozens of miles of roadway. The lava flows also severed major access routes like Highway 137, disrupting transportation and access to lower Puna communities for months.

In areas affected by ashfall from erupting volcanoes, excessive ash can collapse roofs, clog drainage systems, disrupt electricity and contaminate water supplies. Air transportation also grinds to a halt when ash clouds drift into flight paths.

Effects on Residents and Tourists

Volcanic eruptions can have devastating impacts on Hawaii residents, especially those living near active rift zones. Many lose their homes and livelihoods due to lava damage. Exposure to volcanic gases and ash can also cause breathing issues and other health problems.

Tourism slows dramatically during eruption events, dealing a huge economic blow. As an example, Hawaii Volcanoes National Park was mostly closed from May 2018 through late September 2018, turning away over 2 million visitors. Air travel and hotel stays island-wide decline as well.

However, volcanoes also draw tourists and scientists eager to see nature’s spectacular fireworks displays. Some intrepid travelers even roast marshmallows over lava! Still, authorities urge caution as gases, lava bombs and ash eruptions make volcano viewing hazardous.

Although canceled vacations and economic losses sting, Hawaii has rebounded after past eruptions. Communities rally to support displaced residents and rebuild damaged areas. The islands’ resilience and the generosity of aloha spirit always prevail.

For more information, visit the USGS Hawaiian Volcano Observatory and Hawaii County Civil Defense website.

Conclusion

To conclude, less than a quarter of Hawaii’s total land area has been covered by lava flows from the active volcanoes on the islands over the past 10,000 years. However, the volcanoes continue to pose serious threats through explosive eruptions and extensive lava flows impacting infrastructure, residents, agriculture, and tourism across parts of the Hawaiian islands.

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