110 likes | 587 Views
The Wasatch Fault. Why do faults happen?. Faults are areas where the stress of a plate along its borders causes warping and breaking inside the plate. Utah lies inside the North American plate and tensional forces have caused mountains to rise on the Wasatch fault.
E N D
Why do faults happen? • Faults are areas where the stress of a plate along its borders causes warping and breaking inside the plate. • Utah lies inside the North American plate and tensional forces have caused mountains to rise on the Wasatch fault
Shifting occurs both horizontally and vertically along the fault. • However, before the movement occurs the stress along the edges of the fault has to increase a lot. The built up force can cause anywhere from 1-4 meters of slip at once, causing an earthquake.
So what will happen to Utah? • Liquifaction • Flooding • Destruction of buildings • A 2006 estimate predicted 6,200 deaths, 90,000 injured, and $40 billion dollars in damages.
Don’t need to write this part in your notes • During the past 6,000 years, a strong earthquake (magnitude greater than 6.5) has occurred approximately once every 350 years somewhere along the one of the central segments of the Wasatch Fault. The segments that underlie Salt Lake City and Provo produce a large earthquake on average every 1,300 years. The last major earthquake on the Salt Lake City segment was about 1,300 years ago, and on adjoining segments around 2,100 years ago. Experts note that the fault is overdue for another major earthquake, and people in the region have become increasingly aware of the threat in recent years.
Don’t need to write this part in notes • The urban areas of Salt Lake City, Ogden, and Provo, known collectively as the Wasatch Front, lie on soft lake sediments, a remnant of Lake Bonneville. During strong earthquakes, this sediment will cause Earthquake liquefaction, which acts as quicksand. An earthquake on the Wasatch Fault could severely damage gas, electric, water, communication, and transportation lifelines, crippling the 2,000,000 strong Wasatch Front urban area. [2]
Don’t need to write this part in notes • A recent report released by Bob Carey of Utah's Office of Emergency Services and published by the Deseret Morning News in April 2006 predicts what the possible results of a 7.0 earthquake directly hitting the Salt Lake Valley could be. The report predicts that when the quake strikes it could kill up to 6,200 people, injure at least 90,000, and cause $40 billion USD in economic losses. At least 42% of all buildings along the Wasatch Front could be at least moderately damaged.
Don’t need to write this part in notes • The earthquake danger was not known when many structures were built; many hospitals and schools are located on top of faults. About 50% of hospital beds could be eliminated during a quake and the region has about 200,000 unreinforced masonry buildings – buildings particularly vulnerable to shaking – compared to California state's 25,000. Massive landslides are another major threat.[3] • since the 1980s many key structures in the region have begun undergoing extensive seismic retrofitting,