Volcano Watch — Hawaiian volcanoes and their Olympic moments: tall, bigger, longer, and deeper

In Hawai`i, snow sport fans are limited to occasional forays to Mauna Kea, and use equipment ranging from high-tech snowboards to well-placed plastic garbage bags. Hawaii's volcanoes however, top the national and international competition in a variety of performance categories for volcanoes.

For example, Mauna Loa is the tallest mountain in the world. When measured from its base on the down-bowed sea floor, it rises more than 17,000 m (56,000 feet), with a mere 4,170 m (13,680 feet) above sea level. Mauna Kea actually is slightly taller than Mauna Loa above sea level, but its base is not nearly as deep. Mauna Loa towers over the next closest competitor in height, the 8,850 m (29,035 feet) Mount Everest in the Himalayas. Since the base of Mount Everest rests on the continental crust rather than the sea floor, Mauna Loa has a head start, because the depth of the ocean surrounding the island of Hawaii exceeds 5,000 m (16,000 feet). Mauna Loa, in addition to taking the gold medal in height, is the most massive mountain on the planet. Its volume of 80,000 cubic km (19,000 cubic miles) is so great that 3,200 Mount St. Helens could be housed within Mauna Loa.

Although Mauna Loa's smaller neighbor Kilauea certainly doesn't win any size awards, it has had its Olympic moments (which in geologic time are quite long, of course). The current eruption, now in its 20th year, represents a personal best for Kilauea; it is the longest rift zone eruption that is evident in the past 1,000 years. Kilauea has produced longer eruptions originating in the summit area, however, with the 15th century `Aila`au eruption taking the prize. It lasted around 60 years, generating more than twice as much lava and covering four times as much land as the current eruption.

In the lava tube competition, Kilauea's performance is impressive, with flows from the Kazumura tube, formed during the `Aila`au eruption, covering much of the Puna district north of the east rift zone. Forty kilometers (25 miles) long, and with one end 1,100 m (3,600 feet) lower than the other, the Kazumura tube is the longest and "deepest" explored lava-tube cave in the world.

Kilauea's gas output has also won gold medals in the U.S. finals. Since 1983, when the current eruption began, Kilauea has been the largest stationary source of SO2 in the nation. Kilauea's average SO2 emission rate over the last 19 years is about 25% higher than that of the EPA-listed top SO2 polluter, a power plant in Illinois. On a global level however, Kilauea's SO2 emissions are not as significant. Over the last 19 years, Kilauea has erupted around 10 million tons of SO2, compared to the 20 million tons released during the short 1991 eruptive events at Mount Pinatubo, in the Philippines. Kilauea's SO2 gas release is also small compared to global human-made SO2, which is over 200 times greater than Kilauea's contribution.

And since no winter Olympics seem to be complete without some concern about misjudging, it is worth mentioning that changes in judgment about volcanic performance also occur. For example, until recently, the prevailing belief was that Kilauea generally erupts in a relatively quiet, effusive manner generating spectacular lava fountains and flows, with only an occasional explosive event marring the volcano's benign reputation. However, recent research suggests that these explosive events have actually been much more common than previously thought, and that on average Kilauea erupts explosively about as often as does Mount St. Helens. Kilauea will probably repeat this explosive activity in the future; most explosions will come with warning, but the largest could sneak up on us undetected. A large explosion at Kilauea is no match for a Pinatubo-sized eruption, but it would surely make headlines around the world no matter what the judging criteria.

Volcano Activity Update

Eruptive activity of Kilauea Volcano continued effusively at the Pu`u `O`o vent during the past week. Sporadic low fountaining in the crater often lights the night sky. Field observations on February 21 discovered that the side of a "rootless" shield (described in last week's Volcano Watch article) collapsed. Lava was gushing out of the breach and feeding an `a`a flow. The distal end of the two-km-long (1.2-mi-long) flow was near the top of Pulama pali. Small surface flows are observed on Pulama pali, but none are seen in the coastal flats. There are no ocean entries.

There were no earthquakes reported felt during the week ending on February 21