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earthquakes

Down to Earth With: Brian Tucker

Some of the world’s most densely populated cities are at highest risk for earthquake-related disasters. Geophysicist Brian Tucker has spent the last two-plus decades trying to help the developing world avoid such disasters, and in 1991, he founded the nonprofit GeoHazards International (GHI) to bring the developed world’s risk-mitigation techniques to high-risk communities in the developing world.

27 Apr 2015

Small tremor could have triggered big Chilean quake

On April 1, 2014, a magnitude-8.2 earthquake shook the empty stretch of coast where Chile arcs into Peru, a region called the Iquique Gap. The gap is the only part of the 7,000 kilometer-long boundary between the Nazca and South American plates that hadn’t ruptured in the past century, despite a collision rate of almost 65 millimeters per year.

 
11 Apr 2015

March 29, 1936: Notes on Earth's Inner Core

On March 29, 1936, Danish seismologist Inge Lehmann wrote a letter to a colleague in which she argued that seismic waves — specifically P-waves — recorded from distant earthquakes showed some anomalous characteristics. “If you had seen so many records from these distances as I have,” she wrote, “I am sure you would not doubt that the amplitudes are abnormally small.” Within the year, Lehmann published a study based on those unusual amplitudes, work that first proposed that Earth has a solid inner core inside its liquid outer core.

29 Mar 2015

Tohoku tsunami may have gotten a boost from submarine slump

When the magnitude-9 Tohoku earthquake hit Japan on March 11, 2011, the mainshock triggered tsunami waves averaging about 10 meters in height by the time they reached the coast of Japan, from Fukushima in the south to the northern tip of Honshu Island. But one mountainous stretch of coastline known as Sanriku, about 100 kilometers north of the main rupture area, saw waves higher than 40 meters. This oddity has led some scientists to suggest that a submarine landslide, triggered by the earthquake, may have contributed to the tsunami’s extreme height in this region.

 
04 Feb 2015

Lead-up to Icelandic earthquakes seen in groundwater chemistry

Scientists tracking groundwater in Iceland have reported that significant shifts in the water’s chemistry occurred months prior to earthquakes in 2012 and 2013. It’s far too early to apply the findings to earthquake hazard assessment, researchers say, but the results suggest that precursory groundwater changes may also herald earthquakes elsewhere and point toward a potential means of future seismic monitoring.

31 Dec 2014

Benchmarks: December 26, 2004: Indian Ocean tsunami strikes

On Dec. 26, 2004, a magnitude-9.2 earthquake ruptured the seafloor off Indonesia, sending the most destructive tsunami in recorded history across the Indian Ocean. A wall of water and debris slammed the shores of South Asia; some witnesses described it as sounding like a freight train. Tourists and locals alike scrambled to safety inland and atop tall hotels, recording videos of the surging water that inundated their communities. Many were unable to reach higher ground.

26 Dec 2014

Snow triggers quakes on Mount Rainier

A new study indicates that more than 150,000 low-frequency earthquakes that occurred on Mount Rainier over the past decade were caused by snowfall that triggered stick-slip sliding of glaciers.

25 Dec 2014

Hazard lingers after South Napa earthquake

The magnitude-6 earthquake that shook buildings and rattled wineries in California’s Napa Valley on Aug. 24, 2014, continues to affect homes in at least one neighborhood in the city of Napa more than three months later. The quake’s epicenter was about 6 kilometers south of the city, but post-quake movement, or afterslip, along the principal fault line to the north of the epicenter is ongoing, according to a fast-track report prepared by the U.S. Geological Survey (USGS) for the Federal Emergency Management Agency. Scientists involved in producing the 51-page report — released to the public on Tuesday — discussed it at a press conference at the annual meeting of the American Geophysical Union in San Francisco.

17 Dec 2014

Inland earthquake triggers distant tsunami

On Sept. 24, 2013, a magnitude-7.7 earthquake struck southern Pakistan, killing more than 800 people. The quake made global headlines in part due to the birth of a small island it triggered just off the coast — a mound of mud dubbed Quake Island that has since washed away. A new study has found evidence of another curious event linked to the quake: a small tsunami that appears to have been remotely triggered by a submarine landslide far from the earthquake’s inland epicenter.

26 Nov 2014

Seismic friction causes fault iridescence

Although iridescent spots on rocks in Utah’s Wasatch Fault Zone were first recognized two decades ago, scientists haven’t understood their origin, until now. New research shows that the iridescence appears on fault surfaces subjected to flash heating from friction and that the spots can provide clues to ancient seismic events. 

11 Nov 2014

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