Abstract The Hebgen Lake Earthquake Area, in southwestern Montana, extends westward from the east edge of Hebgen Lake through the Madison River Canyon, a narrow, deep gorge cut through the Madison Range, to Missouri Flats, west of the range. Hebgen Lake, about 8 mi (13 km) north of West Yellowstone, Montana, lies at the base of the east flank of the Madison Range directly west of the northwest corner of Yellowstone National Park, Wyoming. The lake is used as a storage reservoir impounded behind Hebgen Dam, an earth-filled structure built by Montana Power Company in 1914. The earthquake area is easily reached from almost any direction by major all-weather surfaced highways (inset map, Fig. 1). The area is accessible from the east through Yellowstone Park’s West Entrance, which leads directly into West Yellowstone; from the south by multi-lane U.S. 20, which also passes through West Yellowstone; from the north via U.S. 191, which threads then arrow, deeply forested and scenic Gallatin Canyon; and from the west via U.S. 287, which passes through Ennis, a ranching center that still retains the flavor of the old west. The West Yellowstone airport also gives access to the area. The Hebgen Lake area is a favorite tourist and reort area. Lodging is available in West Yellowstone and at several motels along the north shore of Hebgen Lake. Excellent campsites, well maintained by the U.S. Forest Service, are along U.S. 191 north of West Yellowstone, and in Madison River Canyon (Montana 287) west of Hebgen Dam. Most services are available throughout the year in West Yellowstone, although many hotels and some restarants close for the winter soon after Labour Day.