Hog Park hit by minor 'quake

The United States Geological Service (USGS) reported a magnitude 3.3 earthquake at 3:02 p.m., Saturday, Nov. 15 in the vicinity of Hog Park Reservoir.

The earthquake was reported at a depth of 2.7 km (1.68 mile) at latitude 41.041°N, longitude 106.903°W, which is approximately 29 miles south of Saratoga.

Some residents of Encampment and Riverside felt a brief, light tremor resulting from the earthquake.

Riverside resident Steve Flauding said he was sitting in his easy chair on Saturday afternoon when he heard glass rattling in his house and felt the ground rumble "for just a second." His wife Sherry was sitting on the couch and Steve said she thought it was just the wind. After they looked up the earthquake on the internet, Steve was proven right.

Penny Walters, of Encampment, was scanning one of the weather websites she frequents Saturday afternoon when she saw a red marker indicating an earthquake near town. After a little research, she posted information on her Facebook page, which was then shared by the Town of Encampment. Walters said she did not actually feel the earthquake.

According to the USGS ShakeMap, residents of Saratoga should not have felt any tremors from the quake.

Hog Park Reservoir is owned and operated by the City of Cheyenne. Brad Brooks, Engineering and Resource Manager for the City of Cheyenne Board of Public Utilities, said none of the instruments or cameras that monitor the reservoir show any indication of damage to the dam. The city is not automatically notified of seismic events under a magnitude of 5.0 and the state engineer does not require a physical check of dams for events under 5.0 according to Brooks.

The city has a series of instruments and cameras that collect data on their dams continuously. The data would show a failure of the dam in the form of an instantaneous water level drop or significant flow increase from the dam outlet, according to Brooks.

If such an event were to occur, the city has emergency action plans in place and the Forest Service and Carbon County Sheriff's office have copies of those plans. If the Hog Park dam were to fail, the Forest Service and the sheriff's office would be contacted immediately and residents downstream of the dam would be notified by authorities of what action is necessary.

According to Marshall Payne, Safety and Security Officer for the City of Cheyenne, the emergency plans include maps that show inundation (flood) areas that include how fast an area would be flooded and how deep the water would get.

Brooks said during the summer the dam is frequently examined during maintenance operations, but access is limited to snowmobile or snowcat this time of year.