Exploring The Volcanic Islands Of Hawaii

Fiery lava flows, steam vents, and craterlakes—for fans of geology and natural wonders, Hawaii’s active volcanoes hold some magnetic appeal. If you’re planning a visit to Hawaii with hopes of seeing a fiery volcano, you may be wondering: which Hawaii island has an active volcano?

If you’re short on time, here’s a quick answer: the Big Island of Hawaii is home to not one but two (!) active volcanoes—Kilauea on the southeastern side, and Mauna Loa encompassing the center of the island. So if you want to glimpse molten lava, the Big Island of Hawaii is your prime destination.

In this comprehensive guide, we’ll explore the unique geography of the Hawaiian islands to uncover why exactly the Big Island ended up with active volcanoes. We’ll look at how the islands formed, differences across the chain, the history of volcanic activity in Hawaii, and specifics on the two active volcanoes that put on a mesmerizing show on Hawaii’s largest island.

How the Hawaiian Islands Formed: The Hawaii Hotspot

Plate Tectonics Create the Chain

The Hawaiian Islands were created by a hotspot deep underground in the Earth’s mantle. As the Pacific tectonic plate drifts northwestward over this relatively stationary hotspot at a rate of approximately 32 miles per million years, volcanoes continue to emerge from the hotspot while older volcanoes move off the hotspot and stop erupting (USGS).

The chain of islands stretching from Hawaii to the Aleutian Trench are essentially volcanoes in various stages of aging, with the southeastern islands being younger and more active while the northwestern islands are older and more eroded.

The hotspot that feeds the Hawaiian volcano chain likely formed over a thermal plume bringing hot material from the lower mantle up to the lithosphere. As the Pacific plate drifts over this plume, magma pushes through cracks and weaknesses in the plate to erupt onto the seafloor.

Over hundreds of thousands of years, the accumulated lava builds volcanic mountains tall enough to emerge from the sea as islands. The oldest main island, Kure Atoll, sits on the northwest end of the chain and last erupted over 28 million years ago.

The youngest island, Hawaii (also known as the Big Island), continues to grow through eruptions from its 5 major volcanoes today.

New Islands Continue to Form

While the northwestward movement of the Pacific plate eventually carries volcanoes off the hotspot to become extinct seamounts, the hotspot itself continues spewing lava to give rise to new volcanic islands. The hotspot is currently fueling eruptions from the Kīlauea volcano on Hawaii’s Big Island.

Since 1952, Kīlauea has added over 500 acres of new land area to Hawaii through lava flows from volcanic vents (USGS).

In fact, a new underwater volcano called Loʻihi is already forming about 20 miles southeast of Hawaii as the Pacific plate drifts over the hotspot. At over 3,000 feet tall from seafloor to summit, Loʻihi is still about 9,750 feet shy of breaching the ocean surface.

But as it continues erupting and accumulating lava flows over tens of thousands of years, Loʻihi will eventually emerge from the sea to become the newest volcanic island in the Hawaiian chain (USGS). The continual formation of the Hawaiian Islands over millions of years serves as an impressive above-water glimpse into Earth’s internal geologic processes.

Understanding Hawaii’s Island Chain

Age and Size Differences Across Islands

The Hawaiian Islands are a chain of volcanic islands located in the central Pacific Ocean. The islands were formed by eruptions from a hot spot under the Pacific tectonic plate over millions of years as the plate moved northwestward.

This has created an island chain with striking differences in age and size across the islands.

The southeastern most island in the chain, Hawaiʻi, is also the youngest at less than 1 million years old. It is still volcanically active with regular eruptions adding new land. At 4,028 square miles, Hawaiʻi is the largest island in the chain.

As you travel northwest along the chain, the islands get progressively older and smaller. Maui, the second largest island, was formed 1-2 million years ago and measures 728 square miles. Oʻahu, home of Honolulu and Waikīkī, is approximately 3 million years old and has an area of 597 square miles.

At the northwestern end of the chain lie remnants of once larger islands that have eroded over 20+ million years. Kauaʻi, nicknamed “The Garden Isle” for its lush greenery, is 5 million years old but has shrunk to 552 square miles.

Tiny Niʻihau and Kaʻula are the oldest fragments at over 20 million years.

This pattern of decreasing age and size perfectly illustrates the hot spot volcanic origin of the Hawaiian archipelago. It’s been described as a classic example of island arc formation in textbooks!

Only the Youngest Islands are Volcanically Active

Related to their ages, only Hawaiʻi and Maui islands continue to see volcanic eruptions and additions of new land in present times. The once active volcanoes on the older northwestern islands have gone extinct over time.

On Hawaiʻi, regular eruptions from the Kīlauea volcano have added over 500 acres of new land in recent decades alone! Lava flows from the ongoing eruption within Halemaʻumaʻu crater have awed visitors since 2008.

Haleakalā volcano on Maui last erupted between 1480-1600 CE before going dormant. Its enormous crater gives glimpse into past mega eruptions. Haleakalā is no longer considered active but may erupt again in the future so bears monitoring.

In contrast, the extinct volcanoes on older islands Oʻahu, Kauaʻi, etc. have weathered over time into scenic but non-threatening peaks. So visitors flock to enjoy stunning landscapes without fear of molten lava!

This pattern again aligns with the southeast to northwest age progression. It proves the volcanic hot spot origin theory as only the islands currently positioned above the deep hot spot see ongoing eruptions.

History of Eruptions in Hawaii

Pre-Contact Eruptions and Legends

The Hawaiian islands were formed by countless eruptions from the Hawaii hotspot over millions of years. According to Hawaiian legends, the fire goddess Pele created the islands. The legends tell epic tales of Pele battling other gods and chiefs with fiery consequences that shaped the land.

Archaeological evidence shows Native Hawaiians have witnessed eruptions for over 1,500 years. Generations passed down accounts of eruptions at Kīlauea and Mauna Loa through chants and stories. For example, charcoal found in lava from Mauna Loa eruptions 3,000-5,000 years ago indicates early Hawaiians observed the spectacular lava flows.

Recent Explosive Eruptions and Lava Flows

Kīlauea has erupted 34 times since 1952, with lava covering over 100 square miles on the southeast side of the island. This makes it one of the most active volcanoes on Earth. Notable eruptions include:

• 1983-2018: Puʻu ʻŌʻō eruption with nearly continuous lava, reshaping the coastline
• 1969-1974: Mauna Ulu eruption which created a lava lake and added 200 acres to the island
• 1959: Kapoho eruption that destroyed the villages of Kapoho and Kalapana

Mauna Loa last erupted 35 years ago in 1984, yet remains an active threat today. The 1984 eruption came within 4.5 miles of Hilo, Hawaii’s largest population center. Thankfully it spared the towns, but taught valuable lessons to improve volcano monitoring and emergency procedures.

Kilauea – Hawaii’s Most Active Volcano

East Rift Zone Constantly Shifts Landscape

Kilauea volcano’s East Rift Zone is an area where the volcano constantly creates new land. Lava flows have added over 500 acres to Hawaii’s Big Island since 1983, changing the landscape dramatically over recent decades.

This zone experiences near-constant activity, with fluid pāhoehoe lava oozing from fissures and advancing outward over older flows. Hiking across this shifting terrain reveals the dynamic processes at work – you’ll witness steaming vents, jagged aa flows, unstable ground and more curiosities.

Pu’u ‘Ō’ō Erupts for 35 Years

The most prominent vent along the East Rift Zone has been Pu‘u ‘Ō‘ō crater. This volcanic cone began erupting in January 1983, keeping up near-continuous activity for over 35 years now! This makes Pu‘u ‘Ō‘ō one of the longest-lived rift zone eruptions ever observed.

During this time, lava from Pu‘u ‘Ō‘ō has covered over 144 square kilometers of land and added approximately 500 acres of new land to Hawaii’s coast (USGS).

This long-lasting eruption has varied over time, with periods of fast, voluminous lava flows as well as episodes of calmer oozing. Pu‘u ‘Ō‘ō’s lava output peaked in the 1980s and early 1990s. Now in its waning years, the eruption continues creating new land but at a slower pace and smaller volume than its earlier phases.

Dramatic 2018 Eruption and Summit Collapse

In April-May 2018, geologists observed dramatic changes signaling a shift in Kilauea Volcano’s activity. The Pu‘u ‘Ō‘ō vent that had erupted for 35 years suddenly went quiet. At the same time, numerous fissures began opening up along Kilauea’s lower East Rift Zone, sending fountains of lava as high as 300 feet into the air!

As this lower Puna eruption captured headlines, another remarkable event was unfolding at Kilauea’s summit. The lava lake within Halema‘uma‘u Crater, which had been continuously present since 2008, rapidly drained away.

Then, the ground itself began collapsing piece by piece as underground voids gave way following the draining of deep magma reservoirs.

The 2018 lower Puna eruption destroyed over 700 homes and lasted for 3 months (USGS). Meanwhile, Halema‘uma‘u Crater’s collapse created a massive sinkhole over 1,000 feet deep! This event showed how much pressure had built up inside Kilauea’s plumbing system before being unleashed by the 2018 eruptions.

Mauna Loa – The Largest Volcano

Mauna Loa, located on the Big Island of Hawaii, is the largest active volcano on Earth. Measuring approximately 2,000 square miles and rising 13,679 feet above sea level, this towering giant has erupted 33 times since written history began in 1843, with eruptions occurring every 6 years on average.

Though less violent than other volcanoes, Mauna Loa’s size and frequency of activity make it a major geological feature of Hawaii.

Frequent But Less Destructive Eruptions

Compared to other active volcanoes, Mauna Loa’s eruptions tend to be less explosive and destructive, characterized by slowly flowing lava rather than dangerous pyroclastic flows or ash clouds. For example, its most recent eruption in 1984 sent lava flows toward the town of Hilo at a rate of only 7 miles per hour.

This relatively gentle pace allowed Civil Defense to evacuate residents before structures were endangered.

Additionally, lava flows typically follow predictable paths along well-established rift zones downslope. Residents have even been able to return to previously threatened neighborhoods and observe eruptions up close once lava diversion barriers were built.

Though Mauna Loa covers almost 20% of Hawaii Island, most of its surface area consists of uninhabited forests, helping minimize threats to infrastructure when eruptions occur.

Monitoring and Predicting Future Activity

An intricate monitoring system run by the USGS Hawaiian Volcano Observatory keeps close watch over Mauna Loa, tracking indicators like increased seismicity and ground deformation that signal impending unrest.

Data analysis allows scientists to map the volcano’s complex plumbing system and model areas where magma accumulates. By recognizing patterns that foreshadow eruptions, officials can reliably predict renewed activity and issue early warnings when necessary.

Advanced space-based radar has also improved ability to forecast lava flow extents, direction, and timing. For example, imagery and topographic data allowed the USGS to simulate the potential impact of a Mauna Loa eruption in 2019.

Though no signs of unrest were present at the time, modeling results helped emergency managers develop updated mitigation plans to protect Hawaiʻi’s residents in the event of future Mauna Loa activity.

With comprehensive monitoring and preparedness efforts in place, scientists remain confident in ability to alert the public of developing eruptive threats.

Conclusion

The Hawaiian islands deliver stunning tropical landscapes dotted with volcanoes thanks to a geologic hot spot and moving Pacific tectonic plate. As the plate carries islands away from the hot spot, they lose volcanic activity over millions of years of erosion.

So despite Hawaii having 5 major islands and numerous smaller ones, only the youngest and largest island—the Big Island of Hawaii—retains active volcanoes.

The two fiery mountains constantly re-shape Hawaii’s Big Island: Kilauea ranks as one of the world’s most active volcanoes, with its east rift zone injecting new land and pouring out rivers of lava over communities, while the massive Mauna Loa less frequently erupts enormous flows that approach towns.

For daring travelers eager to witness eruptions that forcibly create new earth before your eyes, make Hawaii’s Big Island your top destination.

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