Fiscal Year 2007

This annual report documents the locations, magnitudes, and geologic interpretations of earthquakes recorded for the Hanford monitoring region of south-central Washington in fiscal year 2007 (October 2006 through September 2007). The report provides summaries of seismic events recorded during the first three quarters of fiscal year 2007 and contains a more comprehensive discussion of seismic events for the fourth quarter of the fiscal year

Third Quarter Hanford Seismic Report for Fiscal Year 2008

The Hanford Seismic Assessment Program (HSAP) provides an uninterrupted collection of high-quality raw and processed seismic data from the Hanford Seismic Network for the U.S. Department of Energy and its contractors. The Hanford Seismic Assessment Team 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 Hanford Seismic Network and the Eastern Washington Regional Network consist of 44 individual sensor sites and 15 radio relay sites maintained by the Hanford Seismic Assessment Team. For the Hanford Seismic Network, fourteen local earthquakes were recorded during the third quarter of fiscal year 2008. The largest event recorded by the network during the third quarter (May 18, 2008 - magnitude 3.7 Mc) was located approximately 17 km east of Prosser at a depth of 20.5 km. With regard to the depth distribution, five earthquakes occurred at shallow depths (less than 4 km, most likely in the Columbia River basalts), six earthquakes at intermediate depths (between 4 and 9 km, most likely in the pre-basalt sediments), and three earthquakes were located at depths greater than 9 km, within the crystalline basement. Geographically, eight earthquakes occurred in swarm areas and six earthquakes were classified as random events. The largest event recorded by the network during the third quarter occurred on May 18 (magnitude 3.7 Mc) and was located approximately 17 km east of Prosser at a depth of 20.5 km. This earthquake was the highest magnitude event recorded in the 46-47 N. latitude / 119-120 W. longitude sector since 1975. The May 18 event, not reported as being felt on the Hanford site or causing any damage, was communicated to the PNNL Operations Center per HSAP communications procedures. The event is not considered to be significant with regard to site safety and not unprecedented given the site’s seismic history. The Hanford strong motion accelerometer (SMA) stations at the 200 East Area, 300 Area, and the 400 Area were triggered by the May 18 event. The reportable action level of 2% g for Hanford facilities is approximately 12 times larger than the peak acceleration (0.17%) observed at the 300 Area SMA station and no action was required

Third Quater Seismic Report for Fiscal Year 2007

The Hanford Seismic Assessment Program (HSAP) provides an uninterrupted collection of high-quality raw and processed seismic data from the Hanford Seismic Network for the U.S. Department of Energy and its contractors. The Hanford Seismic Assessment Team 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 Hanford Seismic Network and the Eastern Washington Regional Network consist of 41 individual sensor sites and 15 radio relay sites maintained by the Hanford Seismic Assessment Team. For the Hanford Seismic Network, 16 local earthquakes were recorded during the third quarter of fiscal year 2007. The largest event (magnitude 2.0) occurred on April 16, 2007 and was located 4 km southwest of the 400 Area in the Columbia River basalts at a depth of approximately 3 km. Stratigraphically, 7 earthquakes occurred in the Columbia River basalts (approximately 0-5 km depth), 1 earthquake in the pre-basalt sediments (approximately 5-10 km depth), and 8 earthquakes in the crystalline basement (approximately 10-25 km depth). Geographically, 8 earthquakes occurred in swarm areas, and 8 earthquakes were classified as random events. The Hanford SMA network was triggered on the 300 Area and the 400 Area SMA by the 2.0 Mc seismic event that occurred on April 16, 2007. The maximum vertical acceleration was 0.07 % g and the maximum horizontal acceleration was 0.05% g at the 300 Area SMA, 13.5 km from the event. At the 400 Area SMA, only 5.2 km from the event, the maximum vertical acceleration was 0.25 % g and the maximum horizontal acceleration was 0.23% g. These are the first recordings of a small local earthquake on the SMA network. The reportable action level of 2% g for Hanford facilities is approximately 8 times larger than the peak accelerations observed at the 400 Area and no action was required

Fiscal Year 2008

The Hanford Seismic Assessment Program (HSAP) provides an uninterrupted collection of high-quality raw and processed seismic data from the Hanford Seismic Network for the U.S. Department of Energy and its contractors. The HSAP is responsible for locating and identifying sources of seismic activity and monitoring 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 HSAP works with the Hanford Site Emergency Services Organization to provide assistance in the event of a significant earthquake on the Hanford Site. The Hanford Seismic Network and the Eastern Washington Regional Network consist of 44 individual sensor sites and 15 radio relay sites maintained by the Hanford Seismic Assessment Team. During fiscal year 2008, the Hanford Seismic Network recorded 1431 triggers on the seismometer system, which included 112 seismic events in the southeast Washington area and an additional 422 regional and teleseismic events. There were 74 events determined to be local earthquakes relevant to the Hanford Site. The highest-magnitude event (3.7 Mc) occurred on May 18, 2008, and was located approximately 17 km east of Prosser at a depth of 20.5 km. With regard to the depth distribution, 13 earthquakes were located at shallow depths (less than 4 km, most likely in the Columbia River basalts), 45 earthquakes were located at intermediate depths (between 4 and 9 km, most likely in the pre-basalt sediments), and 16 earthquakes were located at depths greater than 9 km, within the crystalline basement. Geographically, 54 earthquakes were located in swarm areas and 20 earthquakes were classified as random events. The May 18 earthquake was the highest magnitude event recorded since 1975 in the vicinity of the Hanford Site (between 46 degrees and 47 degrees north latitude and 119 degrees and 120 degrees west longitude). The event was not reported as being felt on the Hanford Site or causing any damage and was communicated to the Pacific Northwest National Laboratory Operations Center per HSAP communi¬cations procedures. The event is not considered to be significant with regard to site safety and not unprecedented given the site’s seismic history. The Hanford strong motion accelerometer (SMA) stations at the 200 East Area, 300 Area, and 400 Area were triggered by the May 18 event. The maximum acceleration recorded at the SMA stations (0.17% at the 300 Area) was 12 times smaller than the reportable action level (2% g) for Hanford Site facilities

First Quarter Hanford Seismic Report for Fiscal Year 2011

The Hanford Seismic Assessment Program (HSAP) provides an uninterrupted collection of high-quality raw and processed seismic data from the Hanford Seismic Network for the U.S. Department of Energy and its contractors. The HSAP is responsible for locating and identifying sources of seismic activity and monitoring 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 HSAP works with the Hanford Site Emergency Services Organization to provide assistance in the event of a significant earthquake on the Hanford Site. The Hanford Seismic Network and the Eastern Washington Regional Network consist of 44 individual sensor sites and 15 radio relay sites maintained by the Hanford Seismic Assessment Team. The Hanford Seismic Network recorded 16 local earthquakes during the first quarter of FY 2011. Six earthquakes were located at shallow depths (less than 4 km), seven earthquakes at intermediate depths (between 4 and 9 km), most likely in the pre-basalt sediments, and three earthquakes were located at depths greater than 9 km, within the basement. Geographically, thirteen earthquakes were located in known swarm areas and three earthquakes were classified as random events. The highest magnitude event (1.8 Mc) was recorded on October 19, 2010 at depth 17.5 km with epicenter located near the Yakima River between the Rattlesnake Mountain and Horse Heaven Hills swarm areas

Annual Hanford Seismic Report for Fiscal Year 2010

The Hanford Seismic Assessment Program (HSAP) provides an uninterrupted collection of high-quality raw and processed seismic data from the Hanford Seismic Network for the U.S. Department of Energy and its contractors. The HSAP is responsible for locating and identifying sources of seismic activity and monitoring 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 HSAP works with the Hanford Site Emergency Services Organization to provide assistance in the event of a significant earthquake on the Hanford Site. The Hanford Seismic Network and the Eastern Washington Regional Network consist of 44 individual sensor sites and 15 radio relay sites maintained by the Hanford Seismic Assessment Team. During FY 2010, the Hanford Seismic Network recorded 873 triggers on the seismometer system, which included 259 seismic events in the southeast Washington area and an additional 324 regional and teleseismic events. There were 210 events determined to be local earthquakes relevant to the Hanford Site. One hundred and fifty-five earthquakes were detected in the vicinity of Wooded Island, located about eight miles north of Richland just west of the Columbia River. The Wooded Island events recorded this fiscal year were a continuation of the swarm events observed during fiscal year 2009 and reported in previous quarterly and annual reports (Rohay et al. 2009a, 2009b, 2009c, 2010a, 2010b, and 2010c). Most events were considered minor (coda-length magnitude [Mc] less than 1.0) with the largest event recorded on February 4, 2010 (3.0Mc). The estimated depths of the Wooded Island events are shallow (averaging approximately 1.5 km deep) placing the swarm within the Columbia River Basalt Group. Based upon the last two quarters (Q3 and Q4) data, activity at the Wooded Island area swarm has largely subsided. Pacific Northwest National Laboratory will continue to monitor for activity at this location. The highest-magnitude events (3.0Mc) were recorded on February 4, 2010 within the Wooded Island swarm (depth 2.4 km) and May 8, 2010 on or near the Saddle Mountain anticline (depth 3.0 km). This latter event is not considered unusual in that earthquakes have been previously recorded at this location, for example, in October 2006 (Rohay et al. 2007). With regard to the depth distribution, 173 earthquakes were located at shallow depths (less than 4 km, most likely in the Columbia River basalts), 18 earthquakes were located at intermediate depths (between 4 and 9 km, most likely in the pre-basalt sediments), and 19 earthquakes were located at depths greater than 9 km, within the crystalline basement. Geographically, 178 earthquakes were located in known swarm areas, 4 earthquakes occurred on or near a geologic structure (Saddle Mountain anticline), and 28 earthquakes were classified as random events. The Hanford Strong Motion Accelerometer (SMA) network was triggered several times by the Wooded Island swarm events and the events located on or near the Saddle Mountain anticline. The maximum acceleration value recorded by the SMA network during fiscal year 2010 occurred February 4, 2010 (Wooded Island swarm event), approximately 2 times lower than the reportable action level for Hanford facilities (2% g) with no action required

First Quarter Hanford Seismic Report for Fiscal Year 2010

The Hanford Seismic Network and the Eastern Washington Regional Network consist of 44 individual sensor sites and 15 radio relay sites maintained by the Hanford Seismic Assessment Team. The Hanford Seismic Network recorded 81 local earthquakes during the first quarter of FY 2010. Sixty-five of these earthquakes were detected in the vicinity of Wooded Island, located about eight miles north of Richland just west of the Columbia River. The Wooded Island events recorded this quarter is a continuation of the swarm events observed during fiscal year 2009 and reported in previous quarterly and annual reports (Rohay et al; 2009a, 2009b, 2009c, and 2009d). Most of the events were considered minor (coda-length magnitude [Mc] less than 1.0) with only 1 event in the 2.0-3.0 range; the maximum magnitude event (2.5 Mc) occurred on December 22 at depth 2.1 km. The average depth of the Wooded Island events during the quarter was 1.4 km with a maximum depth estimated at 3.1 km. This placed the Wooded Island events within the Columbia River Basalt Group (CRBG). The low magnitude of the Wooded Island events has made them undetectable to all but local area residents. The Hanford SMA network was triggered several times by these events and the SMA recordings are discussed in section 6.0. During the last year some Hanford employees working within a few miles of the swarm area and individuals living directly across the Columbia River from the swarm center have reported feeling many of the larger magnitude events. Strong motion accelerometer (SMA) units installed directly above the swarm area at ground surface measured peak ground accelerations approaching 15% g, the largest values recorded at Hanford. This corresponds to strong shaking of the ground, consistent with what people in the local area have reported. However, the duration and magnitude of these swarm events should not result in any structural damage to facilities. The USGS performed a geophysical survey using satellite interferometry that detected approximately 1 inch uplift in surface deformation along an east-west transect within the swarm area. The uplift is thought to be caused by the release of pressure that has built up in sedimentary layers, cracking the brittle basalt layers with the Columbia River Basalt Formation (CRBG) and causing the earthquakes. Similar earthquake swarms have been recorded near this same location in 1970, 1975 and 1988 but not with SMA readings or satellite imagery. Prior to the 1970s, swarming may have occurred, but equipment was not in place to record those events. The Wooded Island swarm, due its location and the limited magnitude of the events, does not appear to pose any significant risk to Hanford waste storage facilities. Since swarms of the past did not intensify in magnitude, seismologists do not expect that these events will persist or increase in intensity. However, Pacific Northwest National Laboratory (PNNL) will continue to monitor the activity. Outside of the Wooded Island swarm, sixteen earthquakes were recorded, all minor events. Seven earthquakes were located at intermediate depths (between 4 and 9 km), most likely in the pre-basalt sediments and nine earthquakes at depths greater than 9 km, within the basement. Geographically, seven earthquakes were located in known swarm areas and nine earthquakes were classified as random events

Third Quarter Hanford Seismic Report for Fiscal Year 2010

The Hanford Seismic Assessment Program (HSAP) provides an uninterrupted collection of high-quality raw and processed seismic data from the Hanford Seismic Network for the U.S. Department of Energy and its contractors. The HSAP is responsible for locating and identifying sources of seismic activity and monitoring 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 HSAP works with the Hanford Site Emergency Services Organization to provide assistance in the event of a significant earthquake on the Hanford Site. The Hanford Seismic Network and the Eastern Washington Regional Network consist of 44 individual sensor sites and 15 radio relay sites maintained by the Hanford Seismic Assessment Team. The Hanford Seismic Network recorded 23 local earthquakes during the third quarter of FY 2010. Sixteen earthquakes were located at shallow depths (less than 4 km), five earthquakes at intermediate depths (between 4 and 9 km), most likely in the pre-basalt sediments, and two earthquakes were located at depths greater than 9 km, within the basement. Geographically, twelve earthquakes were located in known swarm areas, 3 earthquakes occurred near a geologic structure (Saddle Mountain anticline), and eight earthquakes were classified as random events. The highest magnitude event (3.0 Mc) was recorded on May 8, 2010 at depth 3.0 km with epicenter located near the Saddle Mountain anticline. Later in the quarter (May 24 and June 28) two additional earthquakes were also recorded nearly at the same location. These events are not considered unusual in that earthquakes have been previously recorded at this location, for example, in October 2006 (Rohay et al; 2007). Six earthquakes were detected in the vicinity of Wooded Island, located about eight miles north of Richland just west of the Columbia River. The Wooded Island events recorded this quarter were a continuation of the swarm events observed during the 2009 and 2010 fiscal years and reported in previous quarterly and annual reports (Rohay et al; 2009a, 2009b, 2009c, 2010a, and 2010b). All events were considered minor (coda-length magnitude [Mc] less than 1.0) with a maximum depth estimated at 1.7 km. Based upon this quarters activity it is likely that the Wooded Island swarm has subsided. Pacific Northwest National Laboratory (PNNL) will continue to monitor for activity at this location

Second Quarter Hanford Seismic Report for Fiscal Year 2010

The Hanford Seismic Assessment Program (HSAP) provides an uninterrupted collection of high-quality raw and processed seismic data from the Hanford Seismic Network for the U.S. Department of Energy and its contractors. The HSAP is responsible for locating and identifying sources of seismic activity and monitoring 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 HSAP works with the Hanford Site Emergency Services Organization to provide assistance in the event of a significant earthquake on the Hanford Site. The Hanford Seismic Network and the Eastern Washington Regional Network consist of 44 individual sensor sites and 15 radio relay sites maintained by the Hanford Seismic Assessment Team. The Hanford Seismic Network recorded 90 local earthquakes during the second quarter of FY 2010. Eighty-one of these earthquakes were detected in the vicinity of Wooded Island, located about eight miles north of Richland just west of the Columbia River. The Wooded Island events recorded this quarter were a continuation of the swarm events observed during the 2009 and 2010 fiscal years and reported in previous quarterly and annual reports (Rohay et al; 2009a, 2009b, 2009c, and 2010). Most of the events were considered minor (coda-length magnitude [Mc] less than 1.0) with only 1 event in the 2.0-3.0 range; the maximum magnitude event (3.0 Mc) occurred February 4, 2010 at depth 2.4 km. The average depth of the Wooded Island events during the quarter was 1.6 km with a maximum depth estimated at 3.5 km. This placed the Wooded Island events within the Columbia River Basalt Group (CRBG). The low magnitude of the Wooded Island events has made them undetectable to all but local area residents. The Hanford Strong Motion Accelerometer (SMA) network was triggered several times by these events and the SMA recordings are discussed in section 6.0. During the last year some Hanford employees working within a few miles of the swarm area and individuals living directly across the Columbia River from the swarm center have reported feeling many of the larger magnitude events. Similar earthquake swarms have been recorded near this same location in 1970, 1975 and 1988 but not with SMA readings or satellite imagery. Prior to the 1970s, earthquake swarms may have occurred at this location or elsewhere in the Columbia Basin, but equipment was not in place to record those events. The Wooded Island swarm, due its location and the limited magnitude of the events, does not appear to pose any significant risk to Hanford waste storage facilities. Since swarms of the past did not intensify in magnitude, seismologists do not expect that these events will persist or increase in intensity. However, Pacific Northwest National Laboratory (PNNL) will continue to monitor the activity. Outside of the Wooded Island swarm, nine earthquakes were recorded, seven minor events plus two events with magnitude less than 2.0 Mc. Two earthquakes were located at shallow depths (less than 4 km), three earthquakes at intermediate depths (between 4 and 9 km), most likely in the pre-basalt sediments, and four earthquakes were located at depths greater than 9 km, within the basement. Geographically, six earthquakes were located in known swarm areas and three earthquakes were classified as random events