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First Quarter Hanford Seismic Report for Fiscal Year 2001

Description: 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. 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.
Date: February 27, 2001
Creator: Hartshorn, Donald C; Reidel, Steve; Rohay, Alan C & Valenta, Michelle Melody
Partner: UNT Libraries Government Documents Department

Third Quarter Hanford Seismic Report for Fiscal Year 2000

Description: 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 42 individual sensor sites and 15 radio relay sites maintained by the Hanford Seismic Monitoring staff. The HSN uses 21 sites and the EWRN uses 36 sites; both networks share 16 sites. The networks have 46 combined data channels because Gable Butte and Frenchman Hills East are three-component sites. The reconfiguration of the telemetry and recording systems was completed during the first quarter. All leased telephone lines have been eliminated and radio telemetry is now used exclusively. For the HSN, there were 818 triggers on two parallel detection and recording systems during the third quarter of fiscal year (FY) 2000. Thirteen seismic events were located by the Hanford Seismic Network within the reporting region of 46{degree}-47{degree}N latitude and 119{degree}-120{degree}W longitude; 7 were earthquakes in the Columbia River Basalt Group, 1 was an earthquake in the pre-basalt sediments, and 5 were earthquakes in the crystalline basement. Three earthquakes occurred in known swarm areas, and 10 earthquakes were random occurrences. No earthquakes triggered the Hanford Strong Motion Accelerometers during the third quarter of FY 2000.
Date: September 1, 2000
Creator: Hartshorn, Donald C; Reidel, Steve & Rohay, Alan C
Partner: UNT Libraries Government Documents Department

First Quarter Hanford Seismic Report for Fiscal Year 2001

Description: 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.
Date: February 27, 2001
Creator: Hartshorn, Donald C.; Reidel, Stephen P.; Rohay, Alan C. & Valenta, Michelle M.
Partner: UNT Libraries Government Documents Department

Second and Third Quarters Hanford Seismic Report for Fiscal Year 1999

Description: 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.
Date: October 8, 1999
Creator: Hartshorn, Donald C.; Reidel, Stephen P. & Rohay, Alan C.
Partner: UNT Libraries Government Documents Department

Second Quarter Hanford Seismic Report for Fiscal Year 2003

Description: This describes the earthquakes that occurred on and near the Hanford Site during the second quarter of FY03. Hanford Seismic Monitoring 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. 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 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 Monitoring staff. For the Hanford Seismic Network, there were 271 triggers during the second quarter of fiscal year 2003. Of these triggers, 141 were earthquakes. Twenty earthquakes were located in the Hanford Seismic Network area. Stratigraphically 9 earthquakes occurred in the Columbia River basalt, 2 were earthquakes in the pre-basalt sediments, and 9 were earthquakes in the crystalline basement. Geographically, 6 earthquakes occurred in swarm areas, 2 earthquakes were associated with a major geologic structure, and 12 were classified as random events.
Date: April 16, 2003
Creator: Hartshorn, Donald C.; Reidel, Steve P. & Rohay, Alan C.
Partner: UNT Libraries Government Documents Department

Second Quarter Hanford Seismic Report for Fiscal Year 2000

Description: 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 42 individual sensor sites and 15 radio relay sites maintained by the Hanford Seismic Monitoring staff. The HSN uses 21 sites and the EWRN uses 36 sites; both networks share 16 sites. The networks have 46 combined data channels because Gable Butte and Frenchman Hills East are three-component sites. The reconfiguration of the telemetry and recording systems was completed during the first quarter. All leased telephone lines have been eliminated and radio telemetry is now used exclusively. For the HSN, there were 506 triggers on two parallel detection and recording systems during the second quarter of fiscal year (FY) 2000. Twenty-seven seismic events were located by the Hanford Seismic Network within the reporting region of 46-47 N latitude and 119-120 W longitude; 12 were earthquakes in the Columbia River Basalt Group, 2 were earthquakes in the pre-basalt sediments, 9 were earthquakes in the crystalline basement, and 5 were quarry blasts. Three earthquakes appear to be related to geologic structures, eleven earthquakes occurred in known swarm areas, and seven earthquakes were random occurrences.
Date: July 17, 2000
Creator: Hartshorn, Donald C.; Reidel, Stephen P. & Rohay, Alan C.
Partner: UNT Libraries Government Documents Department

Third Quarter Hanford Seismic report for Fiscal year 2003

Description: Hanford Seismic Monitoring 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. 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 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 Monitoring staff. For the Hanford Seismic Network, there were 356 triggers during the third quarter of fiscal year 2003. Of these triggers, 141 were earthquakes. Thirty-four earthquakes of the 141 earthquakes were located in the Hanford Seismic Network area. Stratigraphically 15 occurred in the Columbia River basalt, 13 were earthquakes in the pre-basalt sediments, and 6 were earthquakes in the crystalline basement. Geographically, 22 earthquakes occurred in swarm areas, 1 earthquake was associated with a major geologic structure, and 11 were classified as random events. During the third quarter, an earthquake swarm consisting of 15 earthquakes occurred on the south limb of Rattlesnake Mountain. The earthquakes are centered over the northwest extension of the Horse Heaven Hills anticline and probably occur at the base of the Columbia River Basalt Group.
Date: September 11, 2003
Creator: Hartshorn, Donald C.; Reidel, Steve P. & Rohay, Alan C.
Partner: UNT Libraries Government Documents Department

Annual Hanford Seismic Report for Fiscal Year 2003

Description: This report describes the seismic activity in and around the Hanford Site during Fiscal year 2003. Hanford Seismic Monitoring 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. 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 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 Monitoring staff. For the Hanford Seismic Network, there were 1,336 triggers during fiscal year 2003. Of these triggers, 590 were earthquakes. One hundred and one earthquakes of the 590 earthquakes were located in the Hanford Seismic Network area. Stratigraphically 35 (34.6%) occurred in the Columbia River basalt, 29 (28.7%) were earthquakes in the pre-basalt sediments, and 37 (36.7%) were earthquakes in the crystalline basement. Geographically, 48 (47%) earthquakes occurred in swarm areas, 4 (4%) earthquakes were associated with a major geologic structure, and 49 (49%) were classified as random events. During the third and fourth quarters, an earthquake swarm consisting of 27 earthquakes occurred on the south limb of Rattlesnake Mountain. The earthquakes are centered over the northwest extension of the Horse Heaven Hills anticline and probably occur near the interface of the Columbia River Basalt Group and pre-basalt sediments.
Date: December 1, 2003
Creator: Hartshorn, Donald C.; Reidel, Steve P. & Rohay, Alan C.
Partner: UNT Libraries Government Documents Department

Annual Hanford Seismic Report for Fiscal Year 2002

Description: This report summarizes the earthquake activity on Hanford for FY 2002. Hanford Seismic Monitoring 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. 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 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 Monitoring staff. For the Hanford Seismic Network, there were 1,177 triggers during fiscal year 2002. Of these triggers, 553 were earthquakes. Two earthquakes were located in the Hanford Seismic Network area. Stratigraphically 13 occurred in the Columbia River basalt, 12 were earthquakes in the pre-basalt sediments, and 17 were earthquakes in the crystalline basement. Geographically, 13 earthquakes occurred in swarm areas, 1 earthquake was associated with major structures, and 28 were random events. There were no earthquake triggers of the Hanford Strong Motion Accelerometers during fiscal year 2002.
Date: November 15, 2002
Creator: Hartshorn, Donald C.; Reidel, Steve P. & Rohay, Alan C.
Partner: UNT Libraries Government Documents Department

Hanford Seismic Annual Report and Fourth Quarter Report for Fiscal Year 1999

Description: 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 ...
Date: January 7, 2000
Creator: Hartshorn, Donald C.; Reidel, Steve P. & Rohay, Alan C.
Partner: UNT Libraries Government Documents Department

Third Quarter Hanford Seismic Report for Fiscal Year 2010

Description: 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 ...
Date: September 29, 2010
Creator: Rohay, Alan C.; Sweeney, Mark D.; Hartshorn, Donald C.; Clayton, Ray E. & Devary, Joseph L.
Partner: UNT Libraries Government Documents Department

First Quarter Hanford Seismic Report for Fiscal Year 2010

Description: 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 ...
Date: March 29, 2010
Creator: Rohay, Alan C.; Sweeney, Mark D.; Hartshorn, Donald C.; Clayton, Ray E. & Devary, Joseph L.
Partner: UNT Libraries Government Documents Department

Second Quarter Hanford Seismic Report for Fiscal Year 2010

Description: 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 ...
Date: June 30, 2010
Creator: Rohay, Alan C.; Sweeney, Mark D.; Hartshorn, Donald C.; Clayton, Ray E. & Devary, Joseph L.
Partner: UNT Libraries Government Documents Department

Second Quarter Hanford Seismic Report for Fiscal Year 2009

Description: 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 over 800 local earthquakes during the second quarter of FY 2009. Nearly all of these earthquakes were detected in the vicinity of Wooded Island, located about eight miles north of Richland just west of the Columbia River. Most of the events were considered minor (magnitude (Mc) less than 1.0) with 19 events in the 2.0-2.9 range. The estimated depths of the Wooded Island events are shallow (averaging less than 1.0 km deep) with a maximum depth estimated at 1.9 km. This places the Wooded Island events within the Columbia River Basalt Group (CRBG). The low magnitude and the shallowness of the Wooded Island events have made them undetectable to most area residents. However, some Hanford employees working within a few miles of the area of highest activity, and individuals living in homes directly across the Columbia River from the swarm center, have reported feeling some movement. The Hanford SMA network was triggered numerous times by the Wooded Island swarm ...
Date: July 31, 2009
Creator: Rohay, Alan C.; Sweeney, Mark D.; Hartshorn, Donald C.; Clayton, Ray E. & Devary, Joseph L.
Partner: UNT Libraries Government Documents Department

First Quarter Hanford Seismic Report for Fiscal Year 2008

Description: 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, forty-four local earthquakes were recorded during the first quarter of fiscal year 2008. A total of thirty-one micro earthquakes were recorded within the Rattlesnake Mountain swarm area at depths in the 5-8 km range, most likely within the pre-basalt sediments. The largest event recorded by the network during the first quarter (November 25, 2007 - magnitude 1.5 Mc) was located within this swarm area at a depth of 4.3 km. With regard to the depth distribution, three earthquakes occurred at shallow depths (less than 4 km, most likely in the Columbia River basalts), thirty-six earthquakes at intermediate depths (between 4 and 9 km, most likely in the pre-basalt sediments), and five earthquakes were located at depths greater than 9 km, within the crystalline basement. Geographically, thirty-eight earthquakes occurred in swarm areas and six earth¬quakes were classified as random events.
Date: March 21, 2008
Creator: Rohay, Alan C.; Sweeney, Mark D.; Hartshorn, Donald C.; Clayton, Ray E. & Devary, Joseph L.
Partner: UNT Libraries Government Documents Department