First Quarter Hanford Seismic Report for Fiscal Year 2001

Hanford Seismic Monitoring provides an uninterrupted collection of high-quality raw and processed seismic data from the Hanford Seismic Network (HSN) for the U.S. Department of Energy and its contractors. Hanford Seismic Monitoring also locates and identifies sources of seismic activity and monitors changes in the historical pattern of seismic activity at the Hanford Site. The data are compiled, archived, and published for use by the Hanford Site for waste management, Natural Phenomena Hazards assessments, and engineering design and construction. In addition, the seismic monitoring organization works with the Hanford Site Emergency Services Organization to provide assistance in the event of a significant earthquake on the Hanford Site. The HSN and the Eastern Washington Regional Network (EWRN) consist of 41 individual sensor sites and 15 radio relay sites maintained by the Hanford Seismic Monitoring staff. For the HSN, there were 477 triggers during the first quarter of fiscal year (FY) 2001 on the data acquisition system. Of these triggers, 176 were earthquakes. Forty-five earthquakes were located in the HSN area; 1 earthquake occurred in the Columbia River Basalt Group, 43 were earthquakes in the pre-basalt sediments, and 1 was earthquakes in the crystalline basement. Geographically, 44 earthquakes occurred in swarm areas, 1 earthquake was on a major structure, and no earthquakes were classified as random occurrences. The Horse Heaven Hills earthquake swarm area recorded all but one event during the first quarter of FY 2001. The peak of the activity occurred over December 12th, 13th, and 14th when 35 events occurred. No earthquakes triggered the Hanford Strong Motion Accelerometers during the first quarter of FY 2001