Local and Global Impacts of the 1783-84 Laki Eruption in Iceland
by Erik Klemetti
Saturday marks the 230th anniversary of the famed Laki (or Skaftár Fires) eruption in Iceland — one of the largest volcanic eruptions in recorded history. It wasn’t a enormous explosion like many people associate with giant eruptions, nothing like Tambora or Krakatau.
However, it did have a profound impact on people living around the entire Northern Hemisphere for years afterwards, although the direct impact the eruption had on the Earth’s climate is still a widely debated and researched topic. In honor of this anniversary, I thought I’d try to give a brief primer on the eruption and why it is such an important eruption, both in terms of Icelandic volcanism and its global impact…
… at 8:32 a.m. Pacific Daylight Time, a magnitude 5.1 earthquake shook Mount St. Helens. The bulge and surrounding area slid away in a gigantic rockslide and debris avalanche, releasing pressure, and triggering a major pumice and ash eruption of the volcano. Thirteen-hundred feet (400 m) of the peak collapsed or blew outwards.
As a result, 24 square miles (62 sq km) of valley was filled by a debris avalanche, 250 square miles (650 sq km) of recreation, timber, and private lands were damaged by a lateral blast, and an estimated 200 million cubic yards (150 million cu m) of material was deposited directly by lahars (volcanic mudflows) into the river channels.
Sixty-one people were killed or are still missing. USGS Photograph taken on May 18, 1980, by Austin Post.
This five-frame sequence of New Horizons images captures the giant plume from Io’s Tvashtar volcano. Snapped by the probe’s Long Range Reconnaissance Imager (LORRI) as the spacecraft flew past Jupiter earlier this year, this first-ever “movie” of an Io plume clearly shows motion in the cloud of volcanic debris, which extends 330 kilometers (200 mi) above the moon’s surface. Only the upper part of the plume is visible from this vantage point — the plume’s source is 130 kilometers (80 mi) below the edge of Io’s disk, on the far side of the moon…
Serendipitously, marine biogeochemist Eric Achterberg at the University of Southampton in England and his colleagues were taking part in a series of research cruises in the Iceland Basin region of the North Atlantic Ocean both during and after the eruption. These three cruises allowed the researchers to measure iron concentrations at the ocean’s surface before, during and after the eruption in areas directly influenced by the plume of iron-rich ash…
Photographer Martin Rietze recently traveled to Japan where he had the incredible opportunity (or near grave misfortune?) of photographing the Sakurajima Valcano in southern Kyushu as it spewed forth smoke, fire, and lava bombs.
If that wasn’t enough the hellish volcano also caused a lightning show that lasted over 20 seconds giving the photographer ample time to flee for his life take these stunning photographs. You can see many more images from the series right here. Of note, the photographer’s grit and fearlessness landed the top photo a feature on NASA’s Astronomy Picture of the Day earlier this week.
Even Modest Volcanic Eruptions May Mask Global Warming Effects
by Megan Gannon
Volcanic eruptions, even small and moderate ones, might counter some of the effects of global warming, new research suggests.
The planet didn’t heat up as much as scientists expected it to from 2000 to 2010 (though it was still the warmest decade on record), and a new study finds that chemical compounds spewed during modest eruptions around the globe could be behind the trend.
When sulfur dioxide emitted by a volcano rises up to the stratospheric aerosol layer of the atmosphere, it undergoes chemical reactions, forming particles that reflect sunlight back into space instead of letting it get to the surface of the planet. This has a cooling effect on Earth that can help mitigate the impacts of heat-trapping greenhouse gasses…
It may look as if a cotton ball is floating over Mount Fuji in this satellite image, but it’s actually a cloud — the kind of cloud that’s known to give an otherworldly look to Japan’s highest peak.
This picture was snapped by DigitalGlobe’s WorldView 2 satellite on Sept. 20, and it’s currently the front-runner in the company’s contest to select the year’s top image. Cast a vote for your favorite on DigitalGlobe’s Facebook page, and check back in January to find out which picture wins out…
One Scientist Argues That Volcanoes, Not Meteorite, Killed Dinosaurs
by Tia Ghose
Volcanic activity in modern-day India, not an asteroid, may have killed the dinosaurs, according to a new study.
Tens of thousands of years of lava flow from the Deccan Traps, a volcanic region near Mumbai in present-day India, may have spewed poisonous levels of sulfur and carbon dioxide into the atmosphere and caused the mass extinction through the resulting global warming and ocean acidification, the research suggests.
The findings, presented Wednesday (Dec. 5) here at the annual meeting of the American Geophysical Union, are the latest volley in an ongoing debate over whether an asteroid or volcanism killed off the dinosaurs about 65 million years ago in the mass die-off known as the K-T extinction.
“Our new information calls for a reassessment of what really caused the K-T mass extinction,” said Gerta Keller, a geologist at Princeton University who conducted the study. For several years, Keller has argued that volcanic activity killed the dinosaurs…
The volcano Eyjafjallajökull, in Iceland, just before dawn on April 23, 2010: The worst is over. Lava flows freely. Earlier, as it punched through the ice cap, it triggered a meltwater flood that destroyed roads and farms, and a steam explosion that hurled ash into the stratosphere, stopping air traffic for a week.
An International Space Station astronaut took this snapshot of Santiago in the Galápagos Islands when the station passed about 250 miles (400 kilometers) overhead on October 28. The bird’s-eye view shows some of the geologic processes that created the islands over a volcanic mantle plume, or hot spot.
Santiago was formed by a shield volcano, whose low, flat summit ridge is seen below the green vegetation that covers the volcano’s south-facing slopes (top left). Shield volcanoes produce extensive lava flows—here lava is visible as dark patches along some coastlines.
Tuff cones, seen as small circles at upper right, are created when hot lava turns the water below to steam, which then explodes up through the lava and scatters it.
A long plume of ash stretches from Russia’s Shiveluch volcano following an eruption October 6, as captured by NASA’s Aqua satellite. The Kamchatka Volcanic Emergency Response Team in Alaska reported that the ash plume from Shiveluch—located near the coast of the Bering Sea—had reached an altitude of 9,800 feet (2,990 meters) above sea level, and had traveled some 140 miles (220 kilometers) from the volcano’s summit.
(via: National Geo) (photo: Jeff Schmaltz, MODIS/NASA)