UPDATE: Potential Quake Hazard In Spokane Area - Spokane, North Idaho News & Weather KHQ.com

UPDATE: Potential Quake Hazard In Spokane Area

Note: There will be a news conf. today at 10am. KHQ.com will stream it LIVE.

Mobile users, click this link to see LIVE stream: http://tinyurl.com/mkjes49

SPOKANE, Wash. - Preliminary interpretations of a recent geophysical survey confirm the presence of earthquake faults and reveal the possibility of previously unknown faults beneath the greater Spokane area.

During the spring of 2013, the U.S. Geological Survey undertook an airborne magnetic survey over the Spokane area to help understand the geologic reasons for a series of earthquakes and ground uplift that occurred several years earlier.

A sequence of 105 small (less than magnitude 4) earthquakes occurred beneath Spokane in 2001, accompanied by a small increase (1/2 inch) in ground elevation.  The shape of the deforming ground surface was consistent with movement on a northeast-trending fault beneath Spokane, yet no known mapped faults in Spokane have been active in the last 1.6 million years. 

To find the Spokane fault that caused 105 earthquakes in 2001, and evaluate its potential for large earthquakes in the future, scientists turned to geophysical tools to "see" below the surface. Knowing a fault's length, depth, and history of earthquakes helps us prepare for future earthquake hazards.

"As the director of Spokane Emergency Management, we work diligently on preparing our community for disasters which includes identifying hazards in our area. The USGS has performed studies and their preliminary findings will help us develop effective mitigation strategies," said Spokane County Sheriff Ozzie Knezovich.

"Geologic processes often bring together rocks with slightly different magnetic properties, and these variations cause very small differences in magnetic fields above the Earth's surface," explained the study's lead author, USGS geophysicist Richard Blakely. 

"In an aeromagnetic survey, a magnetic sensor is flown back and forth close to the ground and along closely spaced, parallel lines.  After data processing, we arrive at a map of ‘magnetic anomalies' reflecting the variations in the magnetic signal of the rocks and geology of the upper part of the Earth's crust."

Movement along a fault is an example of a geologic process that brings together different kinds of rocks. On a magnetic anomaly map, faults often appear as linear features, even though the faults themselves may be concealed below sedimentary deposits, vegetation, or urban development.

Several linear patterns are evident in the new Spokane data. Two prominent anomalies in the southeast corner of the survey extend across the entire area. One of these is caused by the Cheney fault zone; the other is probably caused by a similar, previously unrecognized zone of faults and fractures. The Latah Creek fault and other known faults appear in the new data as complex alignments of magnetic anomalies.

One alignment of magnetic anomalies is of particular interest: It crosses Spokane in a northeast direction, passes through the zone of earthquakes, and coincides with the Spokane fault postulated from ground deformation. 

There are many geologic reasons for linear magnetic anomalies, and the presence of unrecognized faults is just one possibility. Future USGS studies, including airborne LiDAR surveys and ground-based geologic investigations are planned to confirm the Spokane fault.

  • Most Popular StoriesMost Popular StoriesMore>>

  • UPDATE: Motorcycle passenger killed in Rathdrum crash identified

    UPDATE: Motorcycle passenger killed in Rathdrum crash identified

    Monday, June 18 2018 1:53 PM EDT2018-06-18 17:53:47 GMT

    RATHDRUM, Idaho - Members of the Kootenai County Sheriff's Office and the Northern Lakes Fire Department responded to a fatal crash in Rathdrum late Saturday morning. A citizen reported that a truck struck a motorcycle carrying two people in the intersection at W. Lancaster Rd. and N. Huetter Rd. 

    >>

    RATHDRUM, Idaho - Members of the Kootenai County Sheriff's Office and the Northern Lakes Fire Department responded to a fatal crash in Rathdrum late Saturday morning. A citizen reported that a truck struck a motorcycle carrying two people in the intersection at W. Lancaster Rd. and N. Huetter Rd. 

    >>
  • Tests confirm mystery animal shot in Montana was a wolf

    Tests confirm mystery animal shot in Montana was a wolf

    Monday, June 18 2018 12:37 PM EDT2018-06-18 16:37:05 GMT
    Image Courtesy KXLO via KFBBImage Courtesy KXLO via KFBB

    HELENA, Mont. - The mystery is over: Montana wildlife officials confirm that an unusual-looking animal shot in central Montana was actually a wolf.    Montana Fish, Wildlife and Parks officials initially weren't certain what the creature was when a rancher shot it near Denton in May. They noted the legs, front claws and canine teeth were shorter and its ears bigger than normally seen on wolves. 

    >>

    HELENA, Mont. - The mystery is over: Montana wildlife officials confirm that an unusual-looking animal shot in central Montana was actually a wolf.    Montana Fish, Wildlife and Parks officials initially weren't certain what the creature was when a rancher shot it near Denton in May. They noted the legs, front claws and canine teeth were shorter and its ears bigger than normally seen on wolves. 

    >>
  • Victim in domestic violence situation turned house fire speaks out

    Victim in domestic violence situation turned house fire speaks out

    Monday, June 18 2018 6:43 PM EDT2018-06-18 22:43:22 GMT

    SPOKANE, Wash. - It's been a tough 24 hours for the Winant Family.  Kelli Winant says she called police after a situation escalated with she and her boyfriend Saturday after he had been drinking.  "After he beat me pretty good yesterday, he burned our house down,” Kelli Winant Firefighters were at the home in a matter of minutes.

    >>

    SPOKANE, Wash. - It's been a tough 24 hours for the Winant Family.  Kelli Winant says she called police after a situation escalated with she and her boyfriend Saturday after he had been drinking.  "After he beat me pretty good yesterday, he burned our house down,” Kelli Winant Firefighters were at the home in a matter of minutes.

    >>
HD DOPPLER 6i
/
  • Top Stories from KHQHomeMore>>

  • Spokane employee burglarized at work

    Tuesday, June 19 2018 1:56 AM EDT2018-06-19 05:56:23 GMT

    SPOKANE, Wash.- A Spokane man says he's learned the hard way to always lock his car, even if it’s just for 20 seconds. James Parker says thieves burglarized his company truck in a matter of minutes. Behind an alleyway at Mattress Firm off of Division by NorthTown Mall, Parker says he was in the store delivering inventory while his co-worker was across the way at Subway to get food. 

    >>

    SPOKANE, Wash.- A Spokane man says he's learned the hard way to always lock his car, even if it’s just for 20 seconds. James Parker says thieves burglarized his company truck in a matter of minutes. Behind an alleyway at Mattress Firm off of Division by NorthTown Mall, Parker says he was in the store delivering inventory while his co-worker was across the way at Subway to get food. 

    >>
  • Mad Minute stories from Monday, June 18th

    Mad Minute stories from Monday, June 18th

    Tuesday, June 19 2018 1:54 AM EDT2018-06-19 05:54:29 GMT

    Here are the extended versions of the KHQ Local News 11 at 11 Mad Minute stories from Monday, June 18th.

    >>

    Here are the extended versions of the KHQ Local News 11 at 11 Mad Minute stories from Monday, June 18th.

    >>
  • Police seize 2,500 marijuana plants from 6 Tacoma homes

    Police seize 2,500 marijuana plants from 6 Tacoma homes

    Tuesday, June 19 2018 1:51 AM EDT2018-06-19 05:51:59 GMT

    TACOMA, Wash. (AP) - Authorities say eight people have been arrested after police searched six Tacoma houses connected to an illegal marijuana growing operation.    The News Tribune reports authorities seized at least 2,500 marijuana plants from the properties that police searched Monday morning. 

    >>

    TACOMA, Wash. (AP) - Authorities say eight people have been arrested after police searched six Tacoma houses connected to an illegal marijuana growing operation.    The News Tribune reports authorities seized at least 2,500 marijuana plants from the properties that police searched Monday morning. 

    >>