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mary caperton morton

Past penguin populations not dependent on ice extent

Penguins’ lives revolve around ice, so it seems they might be particularly vulnerable to changing ice conditions and ice loss. But a new study charting the rise and fall of penguin populations over the last 30,000 years suggests that past populations have actually increased during times of climate warming and retreating ice.

21 Oct 2014

We're all living in the global aftershock zone

Can a large earthquake trigger another quake hundreds or even thousands of kilometers away? The answer, scientists say, appears to be yes, but when it happens is far from predictable. How does such dynamic triggering affect global earthquake hazards? Perhaps the whole world should be considered an aftershock zone.

19 Oct 2014

Remote triggering of ice quakes

On Feb. 27, 2010, a magnitude-8.8 earthquake struck the subduction zone off the coast of Chile. The resulting Rayleigh surface waves rippled around the world, triggering small earthquakes in many different tectonic settings, including Antarctica. As the surface waves moved across the white continent, a third of Antarctic seismic stations reported shaking coming from so-called “ice quakes.”

19 Oct 2014

Triggered tremor along the San Andreas Fault

The San Andreas Fault (SAF) in California is one of the most active in the U.S., but the 1,300-kilometer-long strike-slip fault seems to only be susceptible to small-scale dynamic triggering. After the magnitude-9 Tohoku quake in Japan in 2011, the SAF experienced an elevated incidence of tremor up and down its length. The tiny tremors were recorded at depths between 16 and 30 kilometers, below the fault’s seismogenic zone.

19 Oct 2014

Casting a seismic shadow

In the week or two before the magnitude-8.6 Indian Ocean earthquake in 2012, Earth was unusually quiet, with few large quakes over magnitude 5. Afterward, seismic activity all over the globe was elevated for more than a week. Then, suddenly, global seismicity dropped off precipitously: Beginning two weeks after the mainshock, no earthquakes of magnitude-6.5 or greater occurred for 95 days.

19 Oct 2014

Kilauea eruptions could shift from mild to wild

Hawaii’s Kilauea volcano is famously effusive: Low-viscosity lava oozes out of the main caldera and two active rift zones along the southern shore of the Big Island. But scientists suspect that Kilauea’s eruptions haven’t always been so mild, and a new study is providing further evidence supporting that notion. In the past 2,500 years, at least two cycles of explosive eruptions lasting several centuries each have rocked the island. The switch from effusive back to explosive is likely to occur again, scientists say, but probably not anytime soon.

14 Oct 2014

Cassini spots new moon in Saturn's rings

Saturn is famous for its rings, but the sixth planet from the sun also has dozens of moons — 62 at last count, 53 of which have names — and now, according to new observations, it may have a 63rd. In April of last year, NASA’s Cassini spacecraft spotted a newly formed object at the edge of Saturn’s outermost A ring.

08 Oct 2014

For cloud formation, a little aerosol goes a long way

Clouds play a starring role in creating and controlling climate, but cloud physics are notoriously difficult to model, leaving wide gaps in understanding how cloud conditions have changed since the pre-industrial era. A new study looking at pristine regions of the sky in the South Pacific is shining some much-needed light on how particulate air pollution interacts with water vapor to form clouds.

06 Oct 2014

How the Spanish invasion altered the Peruvian coast

When Francisco Pizarro landed in Peru in 1532, his band of Spanish conquistadors set off a chain of far-reaching consequences for the people and economics of western South America. A new study has found that the Spanish invasion also changed the shoreline of northern Peru, by actually ending a several-thousand-year cycle of anthropogenic alteration.

05 Oct 2014

Alaskan megathrust fault more active under Kodiak

In 1964, a magnitude-9.2 earthquake ruptured two segments of the Alaskan megathrust fault along more than 900 kilometers from Prince William Sound to Kodiak Island. Historical and paleoseismic evidence has hinted at previous events in this region in 1788 and about 1100, and now a team working on Kodiak Island has found clues of another large event that struck about 500 years ago. The find makes the recurrence interval for the tsunami-producing fault much shorter, potentially increasing the earthquake and tsunami hazard profile, not only for Alaska, but also Hawaii and California.

05 Oct 2014