Report on the field program to record seismic data from the Canadian Patrol Frigate 1 Shock Trial, November 18, 1994. A collaborative program between the GSC and the Navy to acquire unique and otherwise prohibitively expensive seismic data across tectonic elements of Canada's Atlantic margin. The work was completed by teams from: Geological Survey of Canada, Nova Scotia Department of Natural Resources New Brunswick Department of Natural Resources Ministère de l'Énergie et des Ressources du Québec and the Canadian Navy, Department of National Defence Participant List Department of National Defense Cdr D. Byrtus*, Canadian Patrol Frigate Project, Ottawa Cdr P. Hoes, Maritime Command, Halifax Crew aboard HMCS Halifax and HMCS Preserver The Canadian Patrol Frigate Shock Trial Team LCdr S. Garon*, Trial Director J. Czaban, Senior Shock Trial Engineer Lt(N) D. Spagnolo*, Deputy Trial Director E. Kotecki, Charge Deployment and Firing Engineer Geological Survey of Canada Atlantic Geoscience Centre Continental Geoscience Division Dartmouth, Nova Scotia Ottawa, Ontario S. Dehler* F. Marillier* D. Forsyth* R. Jackson* I. Reid* I. Asudeh* C. Keen M.-C. Williamson R. Schieman D. Heffler G. Oakey T. Cartwright P. Giles C. Murphy D. Chian P. Durling D. Vardy P. Potter T. Allen (*Planning and coordination) Universities Dalhousie University Université du Québec Halifax, Nova Scotia Québec City, Québec T. Schell M. Belanger C. Anderson M. Cloutier S. Ellis J. Ortega N. Fagnan Provincial Departments Nova Scotia Department of Natural Resources S. King M. Corey K. MacLeod New Brunswick Department of Natural Resources R. Bouden M. O'Donald R. Phillips C. St. Peter Ministère de l'Énergie et des Ressources du Québec D. Lefebvre P. Rivard Summary On 18 November 1994, a team of scientists from the Atlantic Geoscience Centre, Dartmouth, and the Continental Geoscience Division, Ottawa, successfully coordinated efforts with the Canadian Navy to realize a rare opportunity and record a large charge detonated by DND Naval Forces as CPF Trial Series number 825, approximately 300 km southeast of Halifax. The shot was recorded by 200 instruments forming a 600 km profile across central Nova Scotia, New Brunswick and the Gaspé peninsula of Québec. Clear seismic records were obtained to a shotreceiver offset distance of 900 km and data quality exceeded expectations. The shot was also recorded on stations of the Canadian Standard Station Network (CSN) between Halifax and Schefferville, and provided excellent calibration data to improve the capability of these stations to locate earthquakes in maritime areas with a known history of seismic activity. The data will be reprocessed to improve signal clarity and made available in a future GSC Open File Report and to scientists studying the seismic characteristics of the crust and mantle across the northern Appalachians and the continent-ocean margin of Nova Scotia. Introduction Upon learning of the Department of National Defense plans to detonate a large single charge off the coast of Nova Scotia as part of their Canadian Patrol Frigate (CPF) trials, inquiries were made by GSC personnel as to the feasibility of collaborating with the Navy to acquire seismic data across the Atlantic margin and adjacent continent. The survey presented a unique and very economical opportunity to obtain information from the deep crust and mantle characterizing the tectonic elements of the northern Appalachians and their Atlantic margin. The GrenvilleAppalachian orogenic complex of southern Nova Scotia, New Brunswick, and southeastern Quebec encompasses a geologically complicated region that has recorded opening of the Iapetus Ocean in Late Precambrian time, terrane accretion and continental collision during closure in the Paleozoic, and Mesozoic rifting that opened the modern Atlantic Ocean. Five upper crustal terranes (Meguma, Avalon, Gander, Dunnage and Humber) three lower crustal blocks (Avalon, Central, and Grenville) have been identified on the basis of geological and geophysical observations (Fig.1). Deep seismic reflection profiles across northern Maine and offshore Nova Scotia and Newfoundland have revealed significant differences in terrane structures. Linkages between these two regions, and information on the Nova Scotia to Québec segment in particular, is critical to understanding alongstrike variations in the northern Appalachians. Topics that we hope to address with these new data include: (1) evidence of anomalously high velocity upper mantle similar to that observed beneath central Newfoundland, (2) variations in upper mantle velocities that characterize the Appalachian orogen and the GrenvilleAppalachian orogenic front for comparison with earthquake and controlled source crustal studies in Maine and Quebec, and (3) evidence of relict traces of subduction zones or and linkages between the major crustal blocks. (4) documentation of seismic wave propagation from a given charge size on the continental margin. The data also provide an initial contribution towards the Maritime-Applachian Transect proposed to Lithoprobe in 1992. Field Program A Global Positioning Satellite receiver with an accompanying personal computer (pc) custom programmed to provide coordinates and shot time at the detonation instant were installed and tested by GSC personnel aboard the bridge of HMCS Halifax with the assistance of the CPF shock trial team and the ship's crew. The CPF team collaborated with GSC personnel to interface the pc with the Halifax's detonation circuitry to obtain the precise detonation time required for accurate seismic observations (Fig.2). Software to provide position, course direction and speed was also made available to the shock trial team. No GSC personnel were aboard HMCS Halifax during the trial. Portable recording seismographs from the Continental Geoscience Division were deployed from headquarters established at Bedford Institute, Dartmouth, Nova Scotia and motels at Chipman and Campbelton New Brunswick. Deployment teams including GSC personnel and volunteers from Universities and provincial departments of Nova Scotia, New Brunswick and Québec were organized by GSC personnel from the Atlantic Geoscience Centre. Road and seismic site selection, verification and station positioning were done by GSC teams before and during the deployment to record the shock trial detonation. On 18 November 1994, the 10,000 lb charge of HBX-1 (ca. 15,000 lb TNT equivalent) detonated by DND Naval Forces as CPF Trial Series number 825 was successfully recorded by the landbased teams. The charge was suspended at a depth of 97m in a total water depth of 4077 m at 420 01.103' latitude, 610 12.890' longitude. This charge was the largest of three explosions detonated over a 6day period to test the response of the new Halifax class of patrol frigate to large shock levels. The shot was recorded by an array of 200 GSC instruments that formed a 600 km long profile across central Nova Scotia, New Brunswick and the Gaspé peninsula of Québec (Fig. 1). Clear seismic records were obtained on all receivers to a shotreceiver offset distance of 900 km and data quality exceeded expectations (Fig. 3). In addition, the shot was recorded on seismographic stations of the Canadian Standard Station Network (CSN) at Halifax, Guysborough, Deer lake, Moncton, La Malbaie and Schefferville (Figs. 1 and 4 to 8). The data provide a valuable calibration source to improve the capability of these stations to accurately locate earthquakes in the east coast area with a history of damaging earth tremors. The CSN data indicate that the seismic energy released by the detonation had an equivalent Richter magnitude of 2.7 3.1. No natural earthquakes or unusual sea states were observed from the vicinity of the test site immediately following the detonation. The very cost effective seismic survey with GSC field expenses of less than $20k resulted from the successful collaboration between scientific teams from two Geological Survey divisions, between the federal departments of Natural Resources and National Defence with volunteer assistance from university students and provincial departments from Nova Scotia, New Brunswick and Quebec. The New Brunswick Department of Natural Resources also contributed transportation costs in the form of truck rentals or gas. Assuming the requirements for environmental assessment, press releases and public consultation could be met, a similar shot in a conventional controlled source seismic survey would have cost on the order of hundreds of thousands of dollars. Acknowledgements As in all combined seaborne and landbased operations, preparation and near real time communication are key to effective coordination, execution and ultimately, successful seismic data acquisition. The landbased effort included deployment of 200 recording instruments along secondary and logging roads across the three provinces by a team of over 30 people composed of GSC scientists, members of the Natural Resources departments of the respective provinces, and university students and others registered with the GSC Volunteers Program. A. Tremblay, Institut National de Recherche Scientifique du Quebec, helped select routes in Quebec and coordinated and arranged transportation for teams from the Université du Québec. L. Fyffe and colleaques from the New Brunswick Department of Natural Resources helped route selection in New Brunswick. K. Louden, Dalhousie University, and B. Boehner, Nova Scotia Department of Natural Resources helped coordinate volunteers in Nova Scotia. F. Lombardo of the Canadian Standard Station network at Guysborough, Nova Scotia provided near real time information on the detonation. The seaborne operation was aided and made possible by the notable efforts of Cdr. D. Sweeney and crew of HMCS Halifax, Cdr P. Hoes at Maritime Command, Halifax, LCdr S. Garon, Lt(N) D. Spagnolo, Mr. J. Czaban and Mr. I. Kotecki of the CPF Shock Trial Team and Lt(N) J. Ford on HMCS Preserver. The last minute programming and system design done by D. Sharon and R. Schieman to capture the instant and position of the detonation worked without field trial and ensured the optimum seismic precision. J. Adams and J. Drysdale have provided preliminary estimates from the CSN records. Access to deploy instruments along private roads and property was provided by Bowaters Mersey Paper Co. Ltd., Fraser Inc., and many unnamed and very hospitable private citizens. This cooperative effort between the various individuals and organisations was critical to the efficient and successful deployment and recovery of the instruments in a short time frame over such a vast territory and we gratefully acknowledge their assistance.