Taxonomy term

paleoseismology

Can distant earthquakes trigger submarine landslides?

Large earthquakes can nudge both nearby and distant faults closer to failure, sometimes setting off additional earthquakes halfway around the world. New evidence from the Cascadia Subduction Zone suggests that large seismic events can also trigger submarine landslides, called turbidity currents, perhaps as far as 13,500 kilometers away. If true, researchers say such long-distance connections could complicate interpretations of paleoseismic records from the Cascadia margin and elsewhere that rely on data from turbidites — the stratified remains of the underwater slides — to piece together when past local earthquakes occurred. But not everyone is convinced that long-distance landslide triggering is possible.

23 Oct 2017

Tilted Himalayan temples hold clues to past shaking

The Himalayan Mountains have not been raised gently. The ongoing collision between India and Asia that has uplifted the highest mountain range on Earth is punctuated by large earthquakes. But one region in the northwest Himalaya, known as the Kashmir seismic gap, has remained eerily quiet, save for a magnitude-7.8 event in 1905, and a mysterious quake in 1555. Now, a new study looking at damaged temples in the Chamba district of Himachal Pradesh in India, within the seismic gap, is shedding some light on the two historical quakes.

18 Nov 2016

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

The Bay Area's next 'big one' could strike as a series of quakes

Californians are bracing for when the San Andreas Fault unleashes the next “big one,” but a new study looking at the paleoseismic history of the San Francisco Bay Area suggests that accumulated stress could also be released in a series of moderate to large quakes on satellite faults, rather than by a single great event on the San Andreas.
 

14 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

San Andreas Fault shook Bay Area three times in a century

During the April 18, 1906, magnitude-7.9 earthquake near San Francisco, Calif., 470 kilometers of the San Andreas Fault ruptured between San Juan Bautista, south of San Francisco, and Point Arena, north of the city.

27 Jun 2014

Old photos help scientists relocate 1906 San Francisco quake rupture point

Portola Valley, just south of San Francisco, is famous for its progressive approach to geology. The town was the subject of the first geologic map of California and the first municipality in the state to hire its very own resident geologist. There’s a good reason: The section of the San Andreas Fault that produced the deadly San Francisco quake of 1906 runs right through the town. But where exactly the fault trace lies has long been a mystery. Now, in a new study, researchers have used a combination of new technology and old photographs to relocate the fault line.

25 Nov 2013

Scientists demonstrate strengths and shortcomings of method for determining ancient earthquake size

“A giant Cascadia earthquake, with its accompanying tsunami, has the potential to be the biggest natural disaster in this history of the U.S.,” says Simon Engelhart, a seismologist at the University of Rhode Island. On Jan. 26, 1700, a magnitude-9 earthquake associated with the nearby Cascadia Subduction Zone struck the Pacific Northwest.

12 Sep 2013

Thinking outside the rocks in the search for ancient earthquakes

The eyewitness accounts, written in columns from right to left, top to bottom, testify that there was no warning of the tsunami, no shaking to drive villagers to high ground before the wave hit, drowning rice paddies and swamping a castle moat. The entries, written by merchants, peasants and samurai, all clearly mark the time and date: just after midnight on Wednesday, Jan. 27, 1700.

25 Aug 2011