Monday, October 18, 2010

Idaho isn't Immune from Earthquakes..

Waking up this morning and seeing that Idaho got a 3.2 earthquake 15 miles west of Challis. This kind of surprised me, for some reason I didn't think they had earthquakes. After doing some reading today, I discovered that Idaho is the 5th in ranking for states that have earthquakes.

There were 4 quakes that are noted to be "Historic Quakes"-
* 1944 07 12 - Sheep Mountain, Idaho - M 6.1
* 1975 03 02 - Eastern Idaho - M 6.2
* 1983 10 28 - Borah Peak, Idaho - M 6.9 Fatalities 2
* 2003 09 22 - Rathdrum, Idaho - M 3.3

Seeing these quakes, you have to wonder why these in particular are considered to be "Historic".. I Looks like I need to do some more reading on where in the United States are earthquakes most likely. People need to take alert now and get the essential needs a family must have in the event of another "Historic" earthquake in Idaho.

Below is a History of Earthquakes in Idaho- Abridged from Earthquake Information Bulletin, Volume 4, Number 2, March - April 1972.

Idaho Earthquake History

The first earthquake causing damage in Idaho's earthquake history occurred on November 9, 1884, apparently centering in northern Utah. Six shocks were reported felt at Paris, Idaho, causing considerable damage to houses. People suffered from nausea.

A shock on November 11, 1905, was felt in the southern half of Idaho and parts of Utah and Oregon. At Shoshone, Idaho, walls cracked and plaster fell.

On May 12, 1916, Boise was hit by a shock which wrecked chimneys and caused people to rush into the streets. Reclamation ditches were damaged and the flow of natural gas altered. It was felt at Loon Creek, 120 miles northeast, and in eastern Oregon - an area of 50,000 square miles.

An intensity VII earthquake occurred within the State on July 12, 1944. The Seafoam Ranger Station building shook so hard the occupants thought it was coming apart. Several people reported that the shaking was so violent they were unable to walk. Another observer reported that rocks rose at least a foot in the air and looked like a series of explosions up the hill. Part of the canyon wall collapsed near Lime Creek. Cracks opened 100 yards long in Duffield Canyon and cracks one to three inches across and several hundred yards long opened on the road below Seafoam. Two chimneys fell at Cascade. This shock was felt over 70,000 square miles, including all of central Idaho, and parts of Washington, Oregon, and Montana.

The magnitude 7.1 earthquake at Hebgen Lake, Montana, on August 17, 1959, which killed 28 people, formed "Quake Lake," and did $11 million damage to roads and timber, also caused some damage in Idaho. Intensity VII was experienced in the Henry's Lake, Big Springs, and Island Park areas. Big Springs increased its flow 15 percent and became rusty red colored. A man was knocked down at Edward's Lodge. There was considerable damage to building in the Henry's Lake area. Trees swayed violently, breaking some roots, and cars jumped up and down. Chimneys fell and a 7-foot-thick rock-and-concrete dock cracked.

In the Island Park area chimneys were toppled and wells remained muddy for weeks. At Mack's Inn, a small girl was thrown from bed and hysteria occurred among some guests. Dishes were broken.

An intensity VII earthquake occurred on August 30, 1962, in the Cache Valley area of Utah. Two large areas of land totaling four acres, five feet thick, slid 300 yards downhill at Fairview, Idaho, opening new springs. Plaster walls, and chimneys were cracked and a chimney fell at Franklin. Falling brick at the Franklin School cracked through the roof and plaster was cracked in every room. Additional damage occurred at Preston. This magnitude 5.7 earthquake was felt over an area of 65,000 square miles in five states and cause approximately $1 million in damage.

An intensity VI shock, on November 1, 1942, centered near Sandpoint and affected 25,000 square miles of Washington, Montana, and Idaho. The Northern Pacific Railroad partially suspended operations to inspect the right of way for boulders and slides. Church services were interrupted, but only minor damage was reported by homes.

A February 13, 1945, shock near Clayton, felt over a 60,000 square mile area, broke some dishes at Idaho City and cracked plaster at Weisner.

A locally sharp shock was felt at Wallace on December 18, 1957, damaging the Galena Silver Mine and frightening miners working 3,400 feet underground.

Soda Springs was shaken by a shock on August 7, 1960, which cracked plaster and a concrete foundation. It was only felt over a 900 square mile area.

Two intensity VI shocks were reported in 1963. The first on January 27, was felt over 6,000 square miles and centered near Clayton, where plaster and windows were cracked. Large boulders rolled down the hill near Camp Livingston and aftershocks were felt for a week. The second occurred on September 10 and was a magnitude 4.1 shock. It caused minor damage at Redfish Lake. Thunderous earth noises were heard.

A magnitude 4.9 shock on April 26, 1969, cracked a foundation at Ketchum, plaster at Livingston Mills, and a cement floor at Warm Springs. It was felt over 9,000 square miles.

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