Can intraplate earthquakes produce stronger shaking than at plate boundaries?

Highlights from the Bulletin of the Seismological Society of America's April issue:

2013-03-21

(Press-News.org) Please cite the Bulletin of the Seismological Society of America (BSSA) as the source of this information.

New information about the extent of the 1872 Owens Valley earthquake rupture, which occurs in an area with many small and discontinuous faults, may support a hypothesis proposed by other workers that these types of quakes could produce stronger ground shaking than plate boundary earthquakes underlain by oceanic crust, like many of those taking place along the San Andreas fault.

Published estimates of the 1872 Owens Valley earthquake in southeastern California put the quake at a magnitude 7.4-7.5 to 7.7-7.9. Early work indicates the Owens Valley fault is ~140 kilometers long, and ~113 kilometers ruptured in 1872. Recent work comparing magnitude estimates from reported shaking effects versus fault rupture parameters suggests that the Owens Valley surface rupture was either longer than previously suspected, or that there was unusually strong ground shaking during the event. Colin Amos of Western Washington University and colleagues tested the hypothesis that the 1872 rupture may have extended farther to the south in Owens Valley. They conclude that the 1872 Owens Valley earthquake did not trigger additional rupture in the Haiwee area, indicating that the 1872 rupture was not likely significantly longer than previously reported.

Amos and colleagues dug trenches in the southwestern Owens Valley area to look at the prominent Sage Flat fault east of Haiwee Reservoir. The trench data, combined with dating of the exposed sediment, allowed them to preclude the southern extent of the 1872 rupture from the Sage Flat area and identify two other much older surface-rupturing earthquakes in the area 25,000 to 30,000 years ago. The evaluation of their trench site suggests that the only recent ground disturbance, possibly coincident with the 1872 earthquake, was mostly weak fracturing that may have resulted from ground shaking -- rather than triggered slip along a fault. Soil liquefaction -- the conversion of soil into a fluid-like mass during earthquakes – likely occurred at other nearby saturated wetlands and meadows closer to the axis of the valley.

### "Refining the southern extent of the 1872 Owens Valley Earthquake rupture through paleoseismic investigations in the Haiwee area, southeastern California" by Colin B. Amos (Former postdoc at UC Berkeley, now at Western Washington University; Andrew T. Lutz at Lettis Consultants International, Inc.; Angela S. Jayko, Shannon A. Mahan U.S. at Geological Survey; G. Burch Fisher at University of California, Santa Barbara and Jeffrey R. Unruh at Lettis Consultants International, Inc.

Corresponding author: Colin B. Amos
Colin.Amos@wwu.edu Media contact: Nan Broadbent
press@seismosoc.org Editor's note: For copies of the paper, please contact press@seismosoc.org.

ELSE PRESS RELEASES FROM THIS DATE:

Maternal diabetes impairs methylation of imprinted gene in oocytes

2013-03-21

For the first time, researchers have shown that poorly controlled maternal diabetes has an adverse effect on methylation of the maternal imprinting gene Peg3, contributing to impaired development in offspring. Previous studies have revealed that offspring of diabetic mothers display a higher incidence of malformations and fetal death, even when a one-cell embryo is transplanted from a diabetic to a non-diabetic mother. Diabetic mothers' oocytes tend to exhibit reduced glucose metabolism, compromised communication between cumulus cells and oocytes, mitochondrial malfunction, ...

Researchers link Gulf War Illness to physical changes in brain fibers that process pain

2013-03-21

WASHINGTON — Researchers at Georgetown University Medical Center (GUMC) have found what they say is evidence that veterans who suffer from "Gulf War Illness" have physical changes in their brains not seen in unaffected individuals. Brain scans of 31 veterans with the illness, compared to 20 control subjects, revealed anomalies in the bundles of nerve fibers that connect brain areas involved in the processing and perception of pain and fatigue. The discovery, published online March 20 in PLOS ONE, could provide insight into the mysterious medical symptoms reported by more ...

Follow-up study describes declining efficacy of malaria vaccine candidate over 4 years

2013-03-21

Long-term follow-up of a phase II study from KEMRI-Wellcome Trust Research Programme and Oxford University researchers in Kenya shows that the efficacy of a malaria vaccine candidate, RTS,S, wanes over time and varies with exposure to the malaria parasite. The findings will help to inform which populations are likely to benefit most from the vaccine candidate. They also have important implications for the design of future clinical trials of this and other vaccine candidates and highlight the importance of long-term follow-up studies for assessing vaccine efficacy. The ...

New hope to beat malaria once and for all

2013-03-21

"The 4(1H)-quinolone-3- diarylethers are selective potent inhibitors of the parasite mitochondrial cytochrome bc1 complex," Professor Avery said. "These compounds are highly active against the types of malaria parasites which infect humans, Plasmodium falciparum and Plasmodium vivax," she said. "What is really exciting about this study is that a new class of drugs based on the 4(1H)-quinolone-3- diarylethers would target the malaria parasite at different stages of its lifecycle." This provides the potential to not only kill the parasite in people who are infected, ...

97 percent of UK doctors have given placebos to patients at least once

2013-03-21

A survey of UK doctors found that 97% have prescribed placebo treatments to patients at least once in their career. Researchers at the Universities of Oxford and Southampton in the UK discovered that 97% of doctors have used 'impure' placebo treatments, while 12% have used 'pure' placebos. 'Impure' placebos are treatments that are unproven, such as antibiotics for suspected viral infections, or more commonly non-essential physical examinations and blood tests performed to reassure patients. 'Pure' placebos are treatments such as sugar pills or saline injections which ...

Women abused as children more likely to have children with autism

2013-03-21

Boston, MA — Women who experienced physical, emotional, or sexual abuse as children are more likely to have a child with autism than women who were not abused, according to a new study from Harvard School of Public Health (HSPH). Those who experienced the most serious abuse had the highest likelihood of having a child with autism — three-and-a-half times more than women who were not abused. "Our study identifies a completely new risk factor for autism," said lead author Andrea Roberts, research associate in the HSPH Department of Social and Behavioral Sciences. "Further ...

Scripps scientists discover 'lubricant' for Earth's tectonic plates

2013-03-21

Scientists at Scripps Institution of Oceanography at UC San Diego have found a layer of liquefied molten rock in Earth's mantle that may be acting as a lubricant for the sliding motions of the planet's massive tectonic plates. The discovery may carry far-reaching implications, from solving basic geological functions of the planet to a better understanding of volcanism and earthquakes. The scientists discovered the magma layer at the Middle America trench offshore Nicaragua. Using advanced seafloor electromagnetic imaging technology pioneered at Scripps, the scientists ...

Stem cells entering heart can be tracked with nano-'hitchhikers,' Stanford scientists say

2013-03-21

STANFORD, Calif. — The promise of repairing damaged hearts through regenerative medicine — infusing stem cells into the heart in the hope that these cells will replace worn out or damaged tissue — has yet to meet with clinical success. But a highly sensitive visualization technique developed by Stanford University School of Medicine scientists may help speed that promise's realization. The technique is described in a study to be published March 20 in Science Translational Medicine. Testing the new imaging method in humans is probably three to five years off. Human and ...

University of South Florida researchers play key role in discovery of new drug to combat malaria

2013-03-21

Tampa, FL (March 20, 2013) -- University of South Florida researchers played a key role in an international multidisciplinary project that has yielded a promising new antimalarial drug with the potential to cure the mosquito-borne disease and block its transmission with low doses. Roman Manetsch, PhD, USF associate professor of chemistry, and Dennis Kyle, PhD, USF professor of global health, were co-leaders of the USF team, which helped to discover and develop a series of potent compounds to combat malaria known as the 4-(1H)-quinolone-3-diarylethers, or quinolones. The ...

Expression of emotion in books declined during 20th century, study finds

2013-03-21

The use of words with emotional content in books has steadily decreased throughout the last century, according to new research from the Universities of Bristol, Sheffield, and Durham. The study, published today in PLOS ONE, also found a divergence between American and British English, with the former being more 'emotional' than the latter. The researchers looked at how frequently 'mood' words were used through time in a database of more than five million digitised books provided by Google. The list of words was divided into six categories (anger, disgust, fear, joy, ...

Can intraplate earthquakes produce stronger shaking than at plate boundaries?

ELSE PRESS RELEASES FROM THIS DATE:

LAST 30 PRESS RELEASES: