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

Benchmarks: October 9, 1963: The Vajont Landslide kills 2,500 in Italy

In 45 seconds, everything changed. What had been a towering mountainside collapsed into a pile of rubble; what had been a deep reservoir of placid water became a lethal flood; what had been a valley of small Italian villages was leveled to a barren outwash plain.

09 Oct 2014

Santiaguito Volcano's clockwork behavior provides an exceptional laboratory

If Earth breathes, Santiaguito Volcano in the Western Highlands of Guatemala could be its mouth. Roughly every half hour, like volcanic clockwork, Santiaguito’s active Caliente lava dome expands, filling with gas from depressurizing magma below. Then it exhales, often explosively, and deflates. Over the course of a day, you could almost keep time by it.

28 Sep 2014

Colorado River Basin sees severe groundwater depletion

Over the past 14 years, the Colorado River Basin has experienced its worst drought since precipitation records have been kept, starting in the 1960s. The basin supplies water used for agriculture and in households in seven states, affecting more than 40 million people. In a study recently published in Geophysical Research Letters, researchers have found that the reservoirs that store water in the basin are at record low levels. What’s more, the research shows that in addition to shrinking reservoirs, groundwater is being depleted much faster than previously thought, which could have major implications for the region’s future water security.

24 Sep 2014

In Turkey, the older the fault, the bigger the quake: Good news for Istanbul?

For decades, Istanbul has been bracing for a major earthquake from the dangerously active North Anatolian Fault, which passes just 20 kilometers south of Turkey’s largest city. A new study looking at the age of the fault zone may set a cap on the maximum quake size that could hit Istanbul, suggesting that the older, more mature sections of the zone in the east are capable of bigger earthquakes than the younger sections in the west, which are near the city.

05 Sep 2014

Living in the shadow of Mauna Loa: A silent summit belies a volcano's forgotten fury

After 30 years, no one is quite sure when Hawaii’s Mauna Loa will erupt again. History warns us that the volcano’s current silence is anomalous, and the odds are good that it will reawaken within the next couple of decades. So geologists are already taking steps — upgrading their monitoring tools and talking with the public — to prepare for another eruption.

01 Sep 2014

Kilauea vs. Mauna Loa

In the 19th century, Mauna Loa was the most active volcano in the world. Today, Kilauea is the star. Tourism agencies, journalists, civil defense, and even U.S. Geological Survey Hawaiian Volcano Observatory (HVO) geologists have played a role in funneling public attention toward the Big Island’s youngest volcano. Consequently, some people ignore the other volcanic threats on the island, including Mauna Loa. Without knowing the differences between the two volcanoes, people walk away thinking that if they have seen and interacted with one, they know them all.

01 Sep 2014