U.S. Geological Survey
Hawaiian Volcano Observatory

Volcano Watch

Volcano Watch is a weekly feature provided by scientists at the U.S. Geological Survey

Volcano Watch - May 21, 2000

Mosquito and pig: cautionary tale of two alien species

Mosquitoes are not native to the Hawaiian Islands. Anyone driven away from an outdoor activity or rudely awakened by a biting mosquito would agree that the islands of old were indeed a paradise. That bit of paradise was lost in the early 1800s, when the southern house mosquito arrived, allegedly aboard the sailing ship Wellington. This mosquito has evolved in long and close association with humans. It utilizes any standing water but is particularly adapted to sewage-polluted water associated with people and livestock. By 1900, this mosquito was well established throughout the islands, wherever human activities created the stagnant water habitat necessary for its immature stages.

Most people realize that some mosquitoes transmit serious human disease, but few are aware of the many diseases mosquitoes transmit to domestic and wild animals. Fortunately, no known human diseases transmitted by this mosquito occur in Hawai`i. Unfortunately, two mosquito-transmitted bird diseases have become established.

The date of entry for avian pox and malaria remains a mystery, but the devastating impact of the two diseases on lowland populations of native birds has long been recognized. By 1900, some of the earliest naturalists had observed pox lesions on increasingly rare bird species. Avian malaria and pox, are no longer confined to lowlands, however; both diseases are now prevalent in mid-elevation forests.

How could the transmitting mosquito, so dependent on stagnant water around human settlements, become established in the large remaining tracts of Hawaiian forest? This question was particularly baffling on the windward slope of Mauna Loa, where the porous nature of young volcanic soil prevents most standing water. Enter alien species number two, the feral pig, unwittingly paving the way for mosquitoes into the forest.

European domestic pigs were among the earliest introduced species to arrive in Hawai`i. Without predators or herbivore competitors, these animals adapted well to life in the wet forest and rapidly established large feral populations. The starchy core of native tree ferns is among the pigs' favorite foods. Foraging pigs greedily consume this starch, leaving behind cavities that quickly collect rainwater and fallen leaves. As the tree fern starch and leaves decompose, the water becomes rich with bacteria upon which larval mosquitoes feed. Chemicals from decomposing plant material are attractive to female mosquitoes, ensuring that eggs are laid in a suitable habitat. So, the activity of one alien species provided the habitat needed by another. The mosquito figuratively piggy-backed its way into the forest. Many tree fern cavities are small, containing little more than a cup of water; some are larger and hold 3-4 liters (quarts). Even a small cavity can support development of hundreds of mosquito larvae. Consequently a typical acre of wet forest may produce thousands of mosquitoes that can spread the two bird diseases and have a profound effect on bird populations.

Every year between September and December, the Kilauea Field Station receives dead or dying birds from the Volcano area. Many are infected with avian malaria. Each year fewer `i`iwi, the magnificent red honeycreeper, are seen in the mid-elevation forests, and vast tracts of wet forest are now largely devoid of bird life.

Can we control the diseases that threaten our native forest birds? In the few successful campaigns against mosquito-transmitted human disease (malaria on the mainland and in Europe, dengue in Hawai`i), elimination of the larval mosquito habitat was the winning factor. In the windward forests of Mauna Loa, reduction of feral pig numbers would reduce habitat for mosquitoes, ultimately disrupt disease transmission, and help enable forest-bird populations to rebound.

Mosquitoes would still be produced in agricultural and residential areas near forests, so we should practice mosquito control there as well. Everyone can do their part by eliminating standing water on their property. Cleaning a gutter or turning over a pail in the garden may one day be rewarded by a glimpse of an `i`iwi in your own backyard.

Eruption Update

Eruptive activity of Kilauea Volcano continued during the past week. Lava erupts from Pu`u `O`o and flows through a network of tubes toward the coast near the eastern boundary of Hawai`i Volcanoes National Park. A large skylight in the main tube is visible at night on Pulama pali. Surface flows are intermittently active on the coastal flat between Royal Gardens subdivision and the coast. Lava is entering the ocean at three sites near Waha`ula. Remember that ocean-entry areas are extremely hazardous; explosions occur unpredictably or accompany sudden collapses of new land into the water. The active lava flows are hot and have very thin crust. The steam clouds at the entries are highly acidic and laced with glass particles. Use common sense around hot lava and steam. No earthquakes were reported felt during the week ending on May 18.

May 14, 2000

May 18th marks the 20th anniversary of the catastrophic eruption of Mount St. Helens that laid waste to over 540 square km (200 sq mi) of forest, killing 57 people and countless wildlife. Hundreds of kilometers away in eastern Washington, as much as 5 cm (2 in) of ash fell, closing the interstate highway from Seattle to Spokane for a week and paralyzing air traffic. Local rivers crested at 6 m (20 ft) above their normal height as mudflows triggered by melted glacial ice ripped up bridges, roads, and houses.

Many of us at the Hawaiian Volcano Observatory have vivid memories of this eruption. When Mount St. Helens first began to show signs of life in 1980, the U.S. Geological Survey sent scientists to assess the activity. Most had already gained experience by monitoring eruptions at HVO. For others who had never dreamed of working on an active volcano, the eruption of Mount St. Helens was a dramatic turning point in our careers.

The first sign that magma was rising toward Mount St. Helens was an earthquake swarm beneath the volcano in mid-March 1980. A week later, a small steam explosion at the volcano's summit coated the downwind side of the snow-covered peak with ash. This was the first eruption in the conterminous U.S. since the 1914-1917 eruption of Mount Lassen, and it drew flocks of scientists, news media, and sightseers.

Using techniques that were developed to measure ground deformation on Kilauea, scientists discovered that the north flank of the cone was rapidly bulging outward as magma forced its way into the volcano. The infamous bulge grew about 25 m (85 ft) in 20 days, and the USGS warned that a major eruption was likely.

Area residents, however, had grown complacent about the harmless ash plumes and clamored to be allowed back into the restricted zone. Public officials finally relented and, on Saturday, May 17, allowed people to visit their cabins on Spirit Lake. Those people will be forever grateful that they were ordered to leave the area by nightfall.

At 8:32 the next morning, an earthquake triggered a landslide of the unstable bulge, and within seconds the entire north flank of the mountain was in motion. As the mountainside collapsed, it uncapped the shallow magma body within the cone. The sudden release of pressure on the gas-rich magma caused it to explode violently, unleashing a lateral blast of hot gas and ash. The blast swept northward at nearly the speed of sound, flattening forests like jackstraws as far as 30 km (19 mi) from the volcano.

Meanwhile, the collapse of the north flank had coalesced into the largest debris avalanche in recorded history, surging 23 km (13 mi) down the North Fork of the Toutle River at speeds of 300 km per hour (180 mph) and burying the valley under 45 m (150 ft) of a hummocky mixture of rock, mud, and glacial ice. Later in the day, pyroclastic flows of hot gas, ash, and pumice boiled from the newly formed crater and fanned out over the debris avalanche at the base of the volcano.

In the first six months after the cataclysmic eruption of May 18, a series of much smaller explosive eruptions produced small pyroclastic flows. A lava dome formed in the crater as short sticky lava flows piled up over the vent. Sixteen dome-building eruptions over the next 6 years added to the dome until it was 40 times the size of the King Dome in Seattle. The volcano has been quiet since 1986, except for a few small steam explosions that deposited thin layers of ash in the crater.

To hear more about Mt. St. Helens, come to "After Dark in the Park" at the Kilauea Visitor Center at 7:00 p.m. on Tuesday, May 16. Two geologists from the Hawaiian Volcano Observatory will present a slide show, "Mount St. Helens: Personal Remembrances of a Mighty Eruption."

Eruption Update:

Eruptive activity of Kilauea Volcano continued unabated during the past week. Lava is erupting from Pu`u `O`o and flowing through a network of tubes toward the coast. Lava is visible at times on Pulama pali, and surface flows are active in the coastal flats near the Royal Gardens subdivision private access road. Lava is entering the ocean near the site of Waha`ula, in Hawaii Volcanoes National Park.

Readers are reminded that the ocean-entry areas are extremely hazardous, with explosions accompanying sudden collapses of the new land. The steam clouds are highly acidic and laced with glass particles.

There were no felt earthquakes this week on the island.

May 4, 2000

HVO and Show Biz; unlikely but useful bedfellows

Kilauea is a magnet to volcanologists, visitors, and television production companies alike, drawn from around the word by the spell of its eruptions. Kilauea is also of great interest to those who cannot travel here to see it firsthand. So, it is reasonable that HVO should work with TV crews to bring the Kilauea story into tens of millions of homes on all continents.

Since January 1, three major productions (Pioneer Productions for the Discovery Channel, National Geographic TV, and NBC-Today Show) and several smaller ones have involved HVO staff. Many companies contact HVO first, but the National Park Service must approve any shooting inside the park.

Each production company has its own ideas about what it wants to do. Certain themes, however, carry through. Most TV crews want to show flowing lava and HVO staff members doing something with it-sampling, measuring temperature, determining velocity, etc. We oblige if the volcano cooperates. Many of the companies want to see a lava lake in the crater of Pu`u `O`o and are disappointed that it no longer exists. Nonetheless, they still want to shoot footage of the cone and the murky crater. Finally, many companies want footage of an ocean entry, but only a few are willing to be there at night, when the scenes are the best.

Sources of conflict come not with the footage but with the dialogue and editing. HVO wants a scientifically accurate portrayal of the volcano. This is sometimes difficult to accomplish, when producers want sensational statements. Generally we are rather satisfied with the major documentaries, which strive to be factual. Nonetheless, errors can creep in during editing after the production crew has left the field and our direct involvement has ended.

Misleading impressions are sometimes made. Spectacular scenes from the past are often interspersed with up-to-date footage of the eruption, sometimes in a way that implies an upsurge in current activity. Then we get frantic enquiries from the mainland or elsewhere, wondering if we're about to be overrun.

Rarely are deceptions blatant. Several years ago, a filmmaker was determined to include footage of a car imbedded in a lava flow in Kalapana but could find only rusted-out examples. So, he went to a junkyard and had the top half of a car cut off and trucked out to the flow!

We have some control over other matters. We try to tone down scientific jargon, as Show Biz rightfully requests, but sometimes this makes it hard to explain something we do. We try to use either English or metric units, depending on the desire of the producer. This may seem simple, but HVO, together with most of the world and all scientists, uses metric units. We often have to do quick mental arithmetic or haul out a calculator on the spot when the producer insists on English units.

Finally, there is the question of time. We have jobs to do and sometimes find it hard to accommodate the day or more of shooting that a major production needs. But we try to find the time if at all possible.

These issues aside, the interplay between HVO and television companies is generally positive. Television is a powerful medium, reaches most of the world, and is probably the best way for the public to learn about active, dynamic events such as eruptions. Everyone complains about TV, but most watch it. Even if some concepts don't come through exactly as we would like, 80 percent of our message does. And, in truth, we probably live in an 80-percent world, anyway.

Eruption Update

Eruptive activity of Kilauea Volcano continued unabated during the past week. Lava is erupting from Pu`u `O`o and flowing through a network of tubes toward the coast near the eastern boundary of Hawaii Volcanoes National Park. A large skylight of the main tube is visible on Pulama pali. Surface flows are intermittently active in the coastal flats from the base of Pulama pali, to the Royal Gardens subdivision private access road, and beyond to the coast. Lava is entering the ocean primarily at two locations to the east of Waha`ula. The public is reminded that the ocean-entry areas are extremely hazardous, with explosions accompanying sudden collapses of the new land. The active lava flows are hot and have places with very thin crust. The steam clouds are highly acidic and laced with glass particles.

There were no earthquakes reported felt during the week ending on May 4.

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