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Seismic anomaly may be caused by lost tectonic plate

University researchers have demonstrated that the Isabella anomaly, a region of unusually high-velocity seismic waves in California, is actually a remnant of a lost tectonic plate known as the Farallon plate. Their research was published in the Proceedings of the National Academy of Sciences Monday.

Scientists studying earthquakes in California have debated the nature of the anomaly for years, hypothesizing that it indicated the presence of some mass below the earth that geologists could not identify.

Scientists had long assumed the Farallon plate was swallowed by the Pacific plate millions of years ago when the Pacific and North American plates collided, according to a University press release.

The researchers hypothesized that the Isabella anomaly was part of the Farallon plate when other researchers found another anomaly near a known remnant of the Farallon plate. In their paper, the researchers examined the depth and geography of the Isabella anomaly and concluded it had once been part of the Farallon plate.

“This work has radically changed our understanding of the makeup of the west coast of North America,” said Brian Savage, professor at the University of Rhode Island and a co-author of the study, in the release. “It will cause a thorough rethinking of the geological history of North America and undoubtedly many other continental margins.”

 

Research suggests process of Moon rock formation

New research by Brown geologists suggests the formation of rock in the Moon’s Orientale basin may have followed a pattern similar to the formation of the Moon’s outer rock layers. If this process occurred at other impact sites, it could help explain data previously considered inconsistent with present understanding of lunar rocks.

The findings were published in April’s issue of the journal Icarus, which has already been released.

Using data from NASA’s Lunar Orbiter Laser Altimeter, the researchers hypothesized that the impact leading to the formation of the Orientale basin created an ocean of molten rock, according to a University press release. As the magma cooled, it formed the rock found in the basin.

The cooling process largely resembles the earlier process by which the Moon’s mantle and crust were formed. As a result, rocks that formed in the Orientale basin could easily be mistaken for older lunar rocks, according to the release.

If rocks at other impact sites were formed in similar ways, it could help make sense of findings inconsistent with scientists’ current understandings, said William Vaughan GS, the study’s lead author, in the press release. Rock samples suggesting that the Moon is younger than otherwise believed, for instance, could be from a site like the Orientale basin instead of from the magma cooling that formed the Moon’s outer rock layers.

 

Colonography radiation can be reduced without sacrificing image quality

Clinicians can maintain the quality of colonography images with decreased amounts of radiation, according to a new study by University researchers published in the journal Radiology earlier this month.

“Radiation dose is a concern for many in health care — from the clinicians and patients to the government agencies that regulate the industry,” said Assistant Professor of Diagnostic Imaging Kevin Chang in a Rhode Island Hospital press release. “The theoretical risks of radiation exposure as a cancer-causing agent must be weighed realistically against the substantial benefits of colon cancer screening.”

Colon cancer is the third most prevalent form of cancer in the United States, according to the press release.



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