About Earthquake Studies

On the Earthquake Studies pages, you will find locations of recent earthquakes, waveform data from Montana seismographs, and educational material. Western Montana has a history of large damaging earthquakes, and remains seismically active. Many of these earthquakes occur along faults that do not extend to the Earth's surface, and are thus unmapped and unknown. Seismic hazards associated with earthquakes along these "blind" faults cannot be evaluated with traditional geologic studies and can only be studied by evaluations of data from a permanent network of seismograph stations. Accordingly, the mission of the Montana Bureau of Mines and Geology Earthquake Studies Office is: to monitor, analyze, and report on Montana earthquakes, to make data from earthquake events available to the public, and to measure the seismic hazards present in the State of Montana.

Location

The Earthquake Studies Office is located on the Montana Tech Campus in Butte, Montana. The office is on the 3rd floor of the Museum Building, on the south west side of the Mineral Museum. In 2001 the data acquisition equipment included: radio telemetry units, 8 analog Seismograph drum recorders, 8 computers (2 digital acquisition machines, 1 database computer, 3 seismic analysis computers, 1 outside research computer, and 1 general purpose machine); and Helicorder and Seismic data archives.

History

The Earthquake Studies Office (ESO) opened in June 1980 when the Montana Bureau of Mines and Geology assumed operation of the Butte seismograph station. The Butte seismograph began operation in 1936 following the destructive 1935 Helena Earthquakes and is the longest continuously operating seismograph in Montana. The station had been operated by the Montana School of Mines Montana Tech until it lost federal funding in 1980.The first permanent telemetered seismograph in the Montana networkwas installed in the Highland Mountains south of Butte in 1980 (station LRM). Additional telemetered seismograph stations were installed in southwestern Montana at a rate of about one station per year. By 1982, there were enough seismograph stations in operation to begin locating earthquakes, marking the beginning of the modern Montana earthquake catalog.In 1984, four newstations were installed around Butte to monitor potential seismicity following cessation of underground mine pumping and flooding of the Berekely Pit. No seismicity in the vicinity of the flooded mine was detected so, in 1988, the four Butte area stations were relocated to expand network coverage in more active areas of southwest Montana.

In August 1989, the ESO installed a PC-based data acquisition system to better locate and analyze seismic data. In 1990, the ESO had seismic monitoring coverage extending southeastward to Earthquake Lake where the US Forest Service seasonally operates a seismograph at their Visitor's Center.

In 1996 the ESO received a grant from the US Geological Survey to install nine additional stations along the Lewis and Clark zone, an area of ancient faults extending from the Helena area, west-northwestward to Coeur d'Alene, Idaho. Three of the new stations northwest of Missoula are telemetered to Missoula where their records are recorded along with data from two other stations operated by the Geology Department of the University of Montana. Also in 1996, the ESO assisted the Confederated Salish and Kootenai Tribes of the Flathead Reservation with installation and operation of six seismograph stations in the southern Flathead Valley. Data from the Flathead portion of the Montana seismograph network is telemetered to Ronan for recording.

In 1998, with assistance from the National Institude of Safety and Health, the ESO relocated an existing Bozeman area seismograph station (operating since 1988) to a new site near Bozeman Pass. Two new south-central Montana stations, one near Greycliff, and the second near the Stillwater Mine, south of Absaroka, were also added. In 1999, Montana Seismic Network consisted of 31 seismograph stations in Montana. Additional data form surrounding seismograph networks in Yellowstone National Park, Idaho National Environmental and Engineering Laboratory, Boise State University, and the Canadian Geological Survey were forwarded to ESO via email. In November 1999, Montana's first permanent broadband seismograph station (BOZ) became operational as a cooperating station in the United States National Seismic Network. Bringing the total stations in the network to 32 seismic stations. Then network locates about 10 earthquakes each day.

 

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