Mesa Arch's 'hum' measured to track health of rock structure

For decades, structural engineers have listened to the tiny vibrations of buildings and bridges to detect internal damage or weakness. In recent years, geoscientists have begun employing this technique, called “structural health monitoring,” to discover the hidden inner workings of natural rock features. In a new study, researchers have applied this method for the first time to examine a rock arch — Utah’s famous Mesa Arch — to determine whether this delicate structure is stable or soon to collapse.

12 May 2016

Medieval earthquakes in Nepal may help reveal the region's tectonic future

The magnitude-7.8 Gorkha earthquake in Nepal in April 2015 triggered landslides and damage that killed more than 8,500 people and injured at least 20,000, including many in and around Pokhara, the country’s second largest city. In a new study, scientists have found evidence that the city — also a major center of tourism in Nepal — and its surroundings sit atop debris from several large medieval-age quakes, confirming that the recent temblor is only the latest in a region with a long history of major earthquakes.

21 Apr 2016

Crippling heat stress projected by midcentury in densely populated regions

Extreme heat is the world’s top weather-related killer. Exposure to extreme heat caused more than 7,800 fatalities in the U.S. from 1999 to 2009, according to a 2013 report by the U.S. Centers for Disease Control and Prevention. And a single heat wave last summer killed at least 2,300 people in India, according to NOAA.

05 Apr 2016

Downgoing plate topography stopped 2005 Sumatra rupture

In late March 2005, a magnitude-8.7 earthquake struck off the northwest coast of Sumatra, Indonesia, rupturing a portion of the Sunda Megathrust Fault and further terrorizing a region still reeling from the devastating 2004 Boxing Day earthquake and tsunami just three months prior. The March quake, however, could have been far larger than it was, according to new research. Scientists have identified a topographic barrier on the oceanic Indo-Australian Plate — which descends under the Sunda Plate in the Sumatra Subduction Zone — that may have stopped the 2005 rupture from propagating farther.

04 Apr 2016

Human-induced quakes included in new seismic hazard maps

The U.S. Geological Survey (USGS) regularly releases National Seismic Hazard Maps that summarize hazards from potential ground shaking produced by faults around the country. This year, for the first time, those maps include not only natural earthquakes, but also earthquakes induced by human activities — particularly injection of wastewater produced during oil and gas extraction practices. The new maps were released Monday on the USGS website.

29 Mar 2016

King Oraefajokull

The Öraefajökull Volcano boasts Iceland’s highest peak — 2,109 meters above sea level — and has the reputation of being Iceland’s largest and most violent volcano. Major eruptions in 1362 and 1727 were among the most explosive in the island’s history, and both were accompanied by catastrophic glacial floods. After the 1362 event, the Icelandic word öraefi, originally meaning “area without a harbor,” was rechristened to mean “wasteland.”

29 Mar 2016

Sailors right about sneaky rogue waves

Sailors are notorious for telling tall tales, including legends about monstrous “rogue waves” that appear at sea without warning. Oceanographers have traditionally dismissed such stories because they thought that unusually large waves would be preceded by series of waves of increasing size.

29 Mar 2016

Where fire freezes: All eyes, ears and instruments on Iceland's volatile volcanoes

With examples of every type of volcano on Earth — each with its own eruptive pattern — Iceland presents a special challenge to volcanologists, but also serves as an ideal natural laboratory for studying how volcanic processes evolve.

29 Mar 2016

Eerily quiet Katla

Katla Volcano is located near the southern tip of Iceland, under the Mýrdals­jökull Ice Cap. Ashfall deposits found as far away as Norway and Denmark indicate that Katla erupted at least 20 times between A.D. 930 and the last eruption in 1918. Its present dormancy is the longest-known quiet period in the volcano’s history.

29 Mar 2016

Hekla the heckler

Hekla is one of Iceland’s most active volcanoes, erupting more than 25 times since its first recorded eruption in 1104. The most recent eruptions in 1970, 1980, 1981, 1991 and 2000 have allowed geoscientists to create a detailed eruption profile for the volcano.

29 Mar 2016