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Ancient Quakes May Hint at Risk of Sinking for Part of California Coast

Scientists near Los Angeles have found a new risk for the area during a major earthquake: abrupt sinking of land, potentially below sea level

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A view of the San Andreas Fault looks southeast in the Carrizo Plain, north of Wallace Creek, California, in this undated U.S. Geological Survey photograph, VOA
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Seattle, March 22, 2017: The Big One may be overdue to hit California, but scientists near Los Angeles have found a new risk for the area during a major earthquake: abrupt sinking of land, potentially below sea level.

The last known major quake on the San Andreas fault occurred in 1857, but three quakes over the last 2,000 years on nearby faults made ground just outside Los Angeles city limits sink as much as 3 feet, according to a study published this week in the journal Scientific Reports.

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Seismologists estimate the 800-mile-long San Andreas, which runs most of the length of the state, should see a large quake roughly every 150 years.

Scientists from California State University-Fullerton and the U.S. Geological Survey found evidence the older quakes caused part of the coastline south of Long Beach to drop by 1½ to 3 feet. Today, that could result in the area ending up at or below sea level, said Cal State Fullerton professor Matt Kirby, who worked with the paper’s lead author, graduate student Robert Leeper.

“It’s something that would happen relatively instantaneously,” Kirby said. “Probably today if it happened, you would see seawater rushing in.”

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Some factors unclear

The study was limited to a roughly two-square-mile area inside the Seal Beach National Wildlife Refuge, near the Newport-Inglewood and Rose Canyon faults. Kirby acknowledged that the exact frequency of events on the faults is unclear, as is the risk that another quake will occur in the near future.

The smallest of the historic earthquakes was most likely more intense than the strongest on record in the area, the magnitude 6.3 Long Beach earthquake of 1933, which killed 120 people and caused the inflation-adjusted equivalent of nearly $1 billion in damage.

Today, the survey site is sandwiched by the cities of Huntington Beach and Long Beach, home to over 600,000 people, while nearby Los Angeles County has a population of 10 million.

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Seismologist John Vidale, head of the University of Washington-based Pacific Northwest Seismic Network, said after reviewing the study that he was skeptical such powerful quakes could occur very frequently in the area.

Kirby noted that the team could collect soil core samples only within the relatively undisturbed refuge, and that taking deeper samples would shed light on the seismic record even further back, potentially giving scientists more examples of similar quakes to work from. (VOA)

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USA: Everything you want to know about Security Clearance; Find out here!

A security clearance allows a person access to classified national security information or restricted areas.

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Former CIA Director John O. Brennan speaks at the Council on Foreign Relations in Washington, March 11, 2014. President Donald Trump revoked Brennan's security clearance Wednesday. VOA
Former CIA Director John O. Brennan speaks at the Council on Foreign Relations in Washington, March 11, 2014. President Donald Trump revoked Brennan's security clearance Wednesday. VOA

U.S. President Donald Trump on Wednesday revoked the security clearance of former CIA Director John Brennan. We take a look at what that means.

What is a security clearance?

A security clearance allows a person access to classified national security information or restricted areas after completion of a background check. The clearance by itself does not guarantee unlimited access. The agency seeking the clearance must determine what specific area of information the person needs to access.

What are the different levels of security clearance?

There are three levels: Confidential, secret and top secret. Security clearances don’t expire. But, top secret clearances are reinvestigated every five years, secret clearances every 10 years and confidential clearances every 15 years.

All federal agencies follow a list of 13 potential justifications for revoking or denying a clearance. VOA
All federal agencies follow a list of 13 potential justifications for revoking or denying a clearance. VOA

Who has security clearances?

According to a Government Accountability Office report released last year, about 4.2 million people had a security clearance as of 2015, they included military personnel, civil servants, and government contractors.

Why does one need a security clearance in retirement?

Retired senior intelligence officials and military officers need their security clearances in case they are called to consult on sensitive issues.

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Can the president revoke a security clearance?

Apparently. But there is no precedent for a president revoking someone’s security clearance. A security clearance is usually revoked by the agency that sought it for an employee or contractor. All federal agencies follow a list of 13 potential justifications for revoking or denying a clearance, which can include criminal acts, lack of allegiance to the United States, behavior or situation that could compromise an individual and security violations. (VOA)