MBMG Earthquake Studies Office —ESO
The Earthquake Studies Office, located in Butte, Montana on the Montana Tech campus, is on the third floor of the Natural Resources Building (NRB) which is on the north side of Granite/Park Street at the west end of campus.
The Bridger Canyon seismic station (BCMT) is owned and operated by DAQ Systems, LLC of Bozeman, MT. They provide this station free of charge to the MRSN via a continuous data feed.
The ESO operates the Montana Regional Seismic Network (MRSN), a network of 35 permanent seismic stations located throughout western Montana. The data acquisition equipment includes: radio telemetry units, eight analog seismograph drum recorders, eight computers (two digital acquisition machines, one database computer, three seismic analysis computers, one outside research computer, and one general purpose machine), and Helicorder and Seismic data archives.
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, our mission is to monitor, analyze, and report on Montana earthquakes and make this data available to the public.
The Earthquake Studies Office 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 network was 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 new stations 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 35 seismic stations. The network locates about 10 earthquakes each day.