Information on Hawaii's Volcanoes
The Hawaiian Islands are volcanic in origin. Each Hawaiian island is made up of at least one primary dormant volcano, although many islands are composites of more than one. The Big Island of Hawaii, for instance, is constructed of 5 major volcanoes: Kilauea (which is active and we fly over on our Maui Air - Volcano Air Tours), Mauna Loa, Mauna Kea, Hualalai and Kohala. Mauna Loa is the largest active volcano on Earth. Kilauea, which you can see on a Maui Air tour, is presently one of the most productive volcanoes on Earth (in terms of how much lava it erupts each year). The primary volcanoes on each of the islands are known as shield volcanoes, which are gently sloping mountains produced from a large number of generally very fluid lava flows. These mountains are best viewed from the air on Volcano Air Tour’s Big Island Volcano Tour and the Sunset Volcano Tour. Volcano Air Tours is the only airplane company on Maui with air-conditioned planes authorized to fly over Volcanoes National Park. With 17 years perfect safety record, you can sit at your own window seat and view the two largest Hawaiian islands including the active volcano area.
Hawaiian volcanoes primarily erupt a type of rock known as basalt. When molten, basalt produces liquids of relatively high fluidity, compared to volcanoes that erupt more silica rich magma types such as andesite, dacite or rhyolite. The fluidity of molten basalt favors the formation of lava flows, which is why the Hawaiian volcanoes generally have gentle sloping sides, easily visible on our tours. By contrast, lavas with higher silica content are more viscous and commonly produce either thicker, shorter lava flows, thick blocky deposits and/or thick beds of ash that fall from the sky following explosive eruptions. These other types of volcanoes (common outside of Hawaii) are typically steeper sided, which you won't see on a Maui Air Volcano Tour.
The Hawaiian volcanoes were produced by the Hawaiian hot spot, which is presently under the Big Island of Hawaii (which you'll fly over much of on one of Maui Air's Volcano Air Tours). In general, when you move along the island chain from southeast (Hawaii) to northwest (Kauai), the volcanoes become older and older. The age trend of the volcanoes is thought to be due to the way in which the islands are built on the moving sea floor of the North Pacific Ocean. The Pacific Ocean is mostly floored by a single tectonic plate (known as the "Pacific Plate") that is moving over the layer in the Earth known as the Asthenosphere. This movement takes it to the northwest compared to the layers below it at a rate of 5 to 10 cm/yr (the rate depends on where you are on it). As the plate moves over a fixed spot deeper in the Earth where magma (molten lava) forms, a new volcano can punch through this plate and create an island.
The Hawaiian Islands are believed to be formed from one such 'hot spot'. As the plate moves away, the volcano stops erupting and a new one is formed in its place. With time, the volcanoes keep drifting westward and getting older relative to the one active volcano that is over the hot spot. As they age, the crust upon which they sit cools and subsides. This, combined with erosion of the islands once active volcanism stops, leads to a shrinking of the islands with age and their eventual submergence below the ocean surface.
Importantly, the time over which various active volcanoes on the islands remain active is long (hundreds of thousands of years) so that significant overlap in ages occurs on neighboring islands. For instance although Haleakala volcano on Maui is a great distance away from the presently erupting Kilauea, Haleakala last erupted only about 200 years ago. On Volcano Air Tours you will sight see both islands and be able to compare the two.
Kilauea - Hawaii's most active volcano is toured on a Maui Air volcano air tour.
Kilauea is the home of the mythical Pele, the Hawaiian volcano goddess. Hawaiian chants and oral traditions tell in veiled form of many eruptions fomented by an angry Pele before the first European, the missionary Rev. William Ellis, saw the summit in 1823. The caldera was the site of nearly continuous activity during the 19th century and the early part of this century. Since 1952 there have been 34 eruptions, and since January 1983 eruptive activity has been continuous along the east rift zone. All told, Kilauea ranks among the world's most active volcanoes.
Kilauea is the southeastern most volcano on the Big Island of Hawaii. Topographically Kilauea appears as only a bulge on the southeastern flank of Mauna Loa, and so for many years Kilauea was thought to be a mere satellite of its giant neighbor, not a separate volcano. However, research over the past few decades shows clearly that Kilauea has its own magma-plumbing system, extending to the surface from more than 60 km deep in the earth.
In fact, the summit of Kilauea lies on a curving line of volcanoes that includes Mauna Kea and Kohala and excludes Mauna Loa. In other words, Kilauea is to Mauna Kea as Lo`ihi is to Mauna Loa. Hawaiians used the word Kilauea only for the summit caldera, but earth scientists and, over time, popular usage have extended the name to include the entire volcano.
The Pu‘u ‘O‘O eruption of Kilauea is the volcano’s longest rift-zone eruption in more than 800 years. Since the eruption began in 1983, lava flows have buried 45 square miles (117 km2) of the volcano and added 1,000 acres of new land to the Island of Hawaii. The eruption not only challenges local communities, which must adapt to an ever-changing and sometimes-destructive environment, but also has drawn millions of visitors to Hawaii Volcanoes National Park. U.S. Geological Survey (USGS) scientists closely monitor and evaluate hazards at Hawaii’s volcanoes and also work with park rangers to help ensure safe lava viewing for visitors. Most of the time it is too difficult and dangerous to hike out on the ground. Current lava flows are best seen from the air. The only company on Maui with air-conditioned airplanes authorized to fly over Volcanoes National Park is Volcano Air Tours (Maui Air). These flights can fly you from Maui, over Maui and the Big Island of Hawaii and are less expensive and consume less of your day than combination airliner helicopter tours and you see more scenery and learn from the pilot’s narration.
Loihi Seamount - Hawaii's youngest volcano is not seen on a Maui Air volcano air tour because it is still under water. Loihi Seamount, sometimes known as the "youngest volcano" in the Hawaiian chain, is an undersea mountain rising more than 3000 meters above the floor of the Pacific Ocean but still some 2,000 feet under the ocean surface. Both Loihi and Kilauea volcanoes sit on the flank of the Mauna Loa volcano, an older, larger, and still active volcano on the Big Island of Hawaii, the latter viewable from a Maui Air - Volcano Air Tours. Loihi sits submerged in the Pacific off of the southeastern coast of the Big Island of Hawaii. Although hidden beneath the waves, Loihi is nevertheless taller than Mt. St. Helens was prior to the catastrophic volcanism there in 1980.
Before the 1970's, Loihi was not known to be an active volcano. Instead, it was thought to be a fairly common old seamount volcano of the type that surrounds the Hawaiian Islands. These latter volcanoes are similar in age (80-100 million years old) to the sea floor upon which the Big Island of Hawaii sits. This sea floor was itself created some 6000 km away on the undersea volcanic mountain chain known as the East Pacific Rise. It has slowly moved northwestward to the present location of the Hawaiian Hotspot.
In 1970, ideas about the seamount changed drastically following an expedition that went to Loihi to study an earthquake swarm (intense, repeated seismic activity) that had just occurred there. It was revealed that Loihi was a young, active volcano, rather than an old dead seamount from a bygone aeon. The volcano is mantled with young and old lava flows and is actively venting hydrothermal fluids at it's summit and south rift zone. In August 1996 Loihi volcano rumbled to life again with a vengeance and has been intermittently active since then. In fact, University of Hawaii scientists studying the seamount following the 1996 seismic swarm have found direct evidence of a volcanic eruption there in 1996, making this the first confirmed historical eruption of the seamount.
Mauna Kea - Hawaii's tallest volcano - best viewed on a Maui Air volcano air tour. Mauna Kea is the tallest mountain in the Hawaiian Chain. Its summit rises to an elevation of 13,796 feet (4205m) above sea level and it is located on the island of Hawaii. It is the second largest in sub aerial surface area of the five shield volcanoes that comprise the island of Hawaii, and we fly by it on our Maui Air Volcano Air Tours.
Eruptive History - Mauna Kea is considered to be a dormant shield volcano in what is commonly known as the "post-shield" stage. Submarine eruptions began to build Mauna Kea from the sea floor around 8 million years ago. The basaltic shield stage of volcanism began by at least 3 million years ago. Alkalic post shield activity began about 60-70 thousand years ago and its youngest known eruptions occurred around 4000-5000 years ago.
Mauna Loa - Hawaiian for "Long Mountain", is also located on the Big Island of Hawaii. It rises 13,680 ft. (4,170 m) above sea level. Since 1832, Mauna Loa has erupted 39 times; its last eruption was in 1984 and is still erupting.
Mauna Loa Awakening? The summit of Mauna Loa has been inflating slowly since April/May 2002, following nearly 10 years of slight deflation. The inflation hasn't been constant, with slowdowns in winter 2002-2003 and Spring 2003. But, inflation has been fairly steady in 2004, which suggests that the magma reservoir within the volcano is swelling.
Earthquake activity beneath Mauna Loa increased in early July 2004. HVO reports that the numbers fluctuate weekly but are above "normal". There were more than 350 "long-period" earthquakes beneath Mauna Loa’s summit and the upper southwest rift zone during the first week of September, most which were deep (35 to 50 km) below the ground surface. This is the greatest number of such earthquakes since the beginning of the modern HVO earthquake catalog, which was started in the 1960s. HVO scientists continue to monitor the volcano for signs that might indicate an increase or decrease in activity there.
Mauna Loa is a REALLY tall and big mountain. At 60 miles long and 30 miles wide, it makes up half of the entire island of Hawaii. When one considers that the flanks of Mauna Loa sit on sea floor that is about 16,400 ft (5,000 M) deep, the "height" of this volcano relative to neighboring land (the sea floor) is more like 30,080 ft (9,170 m)! Mauna Loa is the largest active volcano in the world. In fact, using this last measure of its height, it is one of the tallest mountain in the world (although many mountains, such as Mt. Everest in the Himalayan mountain range, sit higher relative to sea level). All large land masses (such as mountains) also push down upon the Earth's crust due to their enormous weight. So, directly beneath Mauna Loa, the sea floor on which it sits is depressed by an additional 26,000 ft (8000 m). Thus, if one wanted to say how thick (at its center) is the lava pile that makes up Mauna Loa, one would need to add its above sea level height, its sea floor to sea level height, and the thickness of its depression in the Pacific sea floor. These total 56,080 ft (17,170 m).
Mauna Loa is a "shield volcano", which means it is a gently sloping mountain produced from a large number of generally very fluid lava flows. This Hawaii volcano has been erupting for at least 100,000 years (possibly more) from a primary volcanic center that is presently manifested by Moku'aweoweo crater at the mountain's summit. It has produced both a'a and pahoehoe flows, and lesser amounts of pyroclastic deposits. The volcano is constructed of a rock type known as tholeiitic basalt. Mauna Loa shares the Hawaiian hot spot with its smaller active siblings Kilauea and Loihi Seamount.
The earliest written account of a Mauna Loa eruption, based upon the observations of an elderly guide (Keaweehu) in the Wilkes exploration party to the summit in 1840-1841, says an eruption took place in 1780. This is shortly after Captain Cook's first visit to the islands of Hawaii. In 1868, an eruption from Mauna Loa caused the largest recorded earthquake in Hawaii, a magnitude 8 by modern standards. The lava flow of 1855-1856 is said to be one of the greatest flows ever seen by modern observers.
The oldest remnants of sub aerial Mauna Loa are to be found in an interesting rock formation known as the "Ninole Volcanic Series". It is a series of steep-sided hills, consisting of thin layers of pahoehoe and a'a lava. These hills form the so-called "Ninole Shield" which is thought to be either the remnants of a pre-Mauna Loa volcano, or uplifted blocks of old Mauna Loa from within the Honuapo-kaoiki fault system. Either way, they are some of the oldest exposed rocks on the southern part of the Big Island of Hawaii.
Haulalai - Hawaii's westernmost volcano is occasionally seen on a Maui Air Volcano Air Tour. Haulalai is a shield volcano located on the Big Island of Hawaii (19.69 N, 155.87 W). The summit of Hualalai rises to 2523m (8271ft) above sea level. The volcano is the westernmost of the 5 major Big Island of Hawaii volcanoes. It has a well-developed Northwest rift zone, a moderately well developed South-Southeast rift zone, and a poorly developed North rift zone. The most recent eruption of 1800-1801 occurred along the Northwest rift zone.
Eruptive History - Haulalai has completed its main Tholeiitic Shield Stage, during which normal and picritic tholeiitic basalts were erupted. These lavas are no longer exposed on the sub aerial surface but have been dredged from submarine portions of the northwest rift zone. Presently, the volcano is mantled by alkalic lavas erupted during the post-shield stage of volcanism (mostly alkali olivine basalts but rare occurrences of Trachyte are also present). The last historical eruption at Hualalai ended in 1801. It is considered to be the third most active volcano in Hawaii, after Mauna Loa and Kilauea, the last of which is featured on a Maui Air Volcano Air Tours. The 1800-1801 eruption produced very fluid, high velocity lava flows that entered the ocean off western Hawaii. Overall, 5 vents issued alkalic basalt lavas, with 2 of these vents producing flows that reached the sea. The total volume of erupted lava has been estimated as 300 million m. This eruption brought abundant xenoliths (xeno = foreign; lith = rock) up from the mantle source that originally produced the lava. The highest elevation vent produced an enormous flow (the Kaupulehu flow) that entered the ocean as 2 discrete lobes. One of these lobes destroyed a Hawaiian village in its path. This eruption at Hualalai is believed to be concurrent with an eruption at neighboring Mauna Loa volcano. Additionally, Hualalai has been essentially simultaneously active with both Mauna Loa and Kilauea in the not so distant past (note: although, we do not in fact know if any eruptions occurred simultaneously, we do know that these three Hawaii volcanoes have been active during much of the last 100 to 200 thousand years).
Hawaii Volcanic Hazards and Monitoring - Although it has been 200 years since the last eruption of Hualalai, it will almost certainly erupt again. Lava flows by far pose the greatest danger in a potential future eruption of Hualalai, because although explosive pyroclastic eruptions have occurred during Holocene times (the past 10,000 years), they are relatively rare and they cover only limited parts of the volcano. The alkalic eruptions at Hualalai have been generally much less explosive than those at neighboring Hawaii volcanoes of Kohala and Mauna Kea. There has been no recently detected magma-related seismicity or ground deformation at Hualalai, making it difficult to say if and when the next eruption might occur.
Hualalai still presents a volcanic hazard as it is near populated areas on Hawaii. For instance, its summit is only 15km away from the town of Kailua-Kona, Hawaii and a flow as voluminous as the 1800 eruption could cover that distance in a few hours. The eruptive recurrence interval of Hualalai for all of Holocene time is on the order of 50 years (about 200 eruptions in 10,000 years). However, mapping and 14C dating studies have indicated that eruptions have occurred in clusters (groups of several eruptions over a few hundred years), separated by several centuries of inactivity.
The Hawaiian Volcano Observatory (HVO) has maintained a seismic station located 3 km east of Hualalai's summit since 1971, which is used to monitor the volcano for signs of activity. During this period, no micro earthquake swarms or harmonic tremors (both indicative of magma migration) have been recorded, although each year Hualalai experiences several magnitude 4 earthquakes. These earthquakes are usually from a deep source off the coast of the Northwest rift zone. This seismicity is apparently not related to movement of magma. However, in 1929 an intense swarm of earthquakes struck Hualalai for a period of a month, which has been interpreted as being due to a magma intrusion too near the surface, without a surface eruption on Hawaii.