Hanford Seismic Annual Report and Fourth Quarter Report for Fiscal Year 1999
This report provides the seismic record at Hanford for FY 1998. 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 40 individual sensor sites and 15 radio relay sites maintained by the Hanford Seismic Monitoring staff. A major reconfiguration of the HSN was initiated at the end of this quarter and the results will be reported in the first quarter report for next fiscal year (FY 2000). For the HSN, there were 390 triggers during the fourth quarter of fiscal year (FY) 1999 on the primary recording system. With the implementation of dual backup systems during the second quarter of the fiscal year and an overall increase observed in sensitivity, a total of 1632 triggers were examined, identified, and processed during this fiscal year. During the fourth quarter, 24 seismic events were located by the HSN within the reporting region of 46 degrees to 47 degrees north latitude and 119 degrees to 120 degrees west longitude; 9 were earthquakes in the Columbia River Basalt Group, 2 were earthquakes in the pre-basalt sediments, 10 were earthquakes in the crystalline basement, and 2 were quarry blasts. One earthquake appears to be related to a major geologic structure, 14 earthquakes occurred in known swarm areas, and 7 earthquakes were random occurrences. The HSN was shut down on September 21, 1999 in preparation for moving the central recording site from the 300 Area of the Hanford Site to the Sigma V building in Richland, Washington. Two additional seismic events were detected by the University of Washington network and are included in our analysis. One additional earthquake (for a total of 22 for this quarter), and one additional quarry blast were located in the study region during the fourth quarter. For the entire fiscal year, 72 earthquakes were located; 39 were earthquakes in the Columbia River Basalt Group, 6 were earthquakes in the pre-basalt sediments, and 27 were earthquakes in the crystalline basement. Geographically, 47 earthquakes occurred in swarm areas, 4 earthquakes were on major structures, and 21 earthquakes were random occurrences. No earthquakes triggered the Hanford Strong Motion Accelerometers during FY 1999. A special seismic event was detected and located on August 14, 1999 at 12:00 noon. This unusual event appears to be related to the demolition of towers in the 100-D Area, and includes signals from seismic waves from the explosions, seismic waves from the impact of the towers, and later (delayed) acoustic signals from the explosions.
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
- Sponsoring Organization:
- US Department of Energy (US)
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 15010241
- Report Number(s):
- PNNL-11557-12; EY3542301; TRN: US200502%%549
- Resource Relation:
- Other Information: PBD: 7 Jan 2000
- Country of Publication:
- United States
- Language:
- English
Similar Records
Second and Third Quarters Hanford Seismic Report for Fiscal Year 1999
Hanford Seismic Report for Fiscal Year 2000