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--> 4 An Alternative Approach Background As mentioned in Chapter 1, the CTBT treaty language contains voluntary confidence-building measures. If any blast is detonated as an explosion (a single delay) of more that 300 metric tons of explosives anywhere in a nation's territory, the treaty suggests that the nation should provide information about each blast to the Comprehensive Test Ban Treaty Organization (CTBTO) in Vienna. Such large single blasts are quite rare. The information should provide, possibly in advance, “details on location, time, quantity and type of explosives used, as well as on the configuration and intended purpose of the blast.” In addition, the treaty asks that each state party, after the entry into force of the treaty, provide to the CTBTO's Technical Secretariat on a voluntary basis as soon as possible information related to those other chemical explosions (e.g., ripple- or delayed-fired blasts) that total greater than 300 metric tons. The information would include “(a) the geographic locations of sites where the explosions originate, (b) the nature of activities producing them and the general profile and frequency of such explosions, and (c) any other relevant detail, if available.” Cooperative Measures. Passive Cooperation Prominent among the “relevant detail” in the previous paragraph could be a voluntary, one-time reporting in the first year after entry into force of the CTBT of the times and locations for three of the largest blasts from mines blasting over 300 metric tons of explosives. Additional information on charge per delay and delay intervals would also be useful. In subsequent years, additional requests for routine blasting information from a mine would be rare. If these one-time data were available
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--> from most mines that emit detectable seismic signals, it would be possible for monitoring agencies to construct a grid of travel-time models and corrections that would enable very accurate locations for all events at or near those mines. Such data would also make it possible to acquire and keep updated a library of characteristic events from each mine so that a good record at even a single seismic station could be used to identify precisely from which mine, by name, the signal came. This ability would greatly reduce the ambiguity of many small signals detected by the CTBTO seismic monitoring system and would make it possible to rapidly obtain confidence-building information from the mine to explain any questionable signals. The determination of blast origin times and location would, ideally, be accurate to the nearest 0.1 second and 100 meters. Larger errors (e.g., minutes) in the origin time, would not be a serious problem; however, accuracy of one second or better is desirable. The required time accuracy could be obtained by manually depressing a firing switch simultaneously with an accurate radio or satellite time mark and allowing for an experimentally determined firing delay. Another, possibly more accurate method of time estimation could be using a signal from a near-source seismometer equipped with a global positioning satellite (GPS) time-code receiver. The location accuracy of the initial explosion, and possibly of the centroid of the explosions, could be determined by reference to a topographic map or by use of a hand-held GPS receiver. Some mine operations, particularly those with a history of rock failures, may choose to participate in the data gathering even if their explosions fall below the 300 metric ton threshold. Data from these mines could be useful if there were local seismographic networks near the mines (e.g., such as in California) or if the shots were particularly well-coupled or concentrated in time (e.g., large charges per delay and/or short delay intervals). Information on significant collapses or other rock failures in mines that might be observed seismically was not suggested as one of the voluntary measures in the treaty. However, it would be extremely useful from a monitoring point of view if mine operators would report the location and approximate time of up to three—if any—of their largest collapses or rock bursts that occurred just before or within a few years after entry into force of the CTBT. Active Cooperation Those very few mining operations, as discussed in Chapter 3, that might emit large, ambiguous signals that might cause consultation and clarification inquiries from other nations may want to advance to active measures, such as the installation of an unintrusive, on-site monitoring system of the type discussed in the DOE Working Group report (see text box in Chapter 3). Some of these data may be transmitted to the inquiring countries and to the CTBTO via the appropriate U.S. agencies. Such efforts would be in addition to the passive data gathering efforts outlined in the previous section.
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--> How Cooperation Could Work A technical agency (or agencies) of the federal government (e.g., the Mine Safety and Health Administration and/or the U.S. Geological Survey)8 would be responsible for collecting mine blast and event data and providing them to a policy-oriented agency of the government (e.g., the “U.S. CTBT National Authority,” yet to be established). The policy agency would be responsible for reviewing the data and sending the appropriate information to the CTBTO's Technical Secretariat. The designated U.S. technical agency would be responsible for determining which mines should be asked to participate and would receive and collate the data from the mines. The data would then be evaluated in comparison with seismological records of events, with the goal of identifying those mines whose seismic signals are visible to the International Monitoring System (IMS). Those mining operators would be asked if they would volunteer additional calibration data that could be used in the case of a request for consultation and clarification under the treaty. The results of this data gathering and analysis would be forwarded to the policy agency for possible transmittal to the CTBT Organization, in compliance with treaty confidence-building measures. Operators for those few mines that generate seismic signals large enough to be located by the IMS and appear on the bulletins distributed to all parties to the treaty may choose to deploy an on-site, active monitoring system such as that proposed by the DOE Working Group. The data and results of the on-site fingerprinting exercise would also be provided to the policy agency, which could transmit the relevant information to the CTBTO, if appropriate. In the year of the treaty's entry into force (EIF), or earlier, the U.S. technical agency would survey the mining industry with respect to its use of explosions over 300 metric tons. Subsequent annual surveys would be used to identify new mines blasting over that threshold (and mines no longer conducting large blasts), as well as mines having had significant collapse events. Prior to EIF, professional and industry associations should begin educating their members on the possible impact of the CTBT on the industry, the importance of communication and collaboration that will be needed from some mines, and the types and accuracy of the information that is desired. 8 Of existing federal agencies, the Mine Safety and Health Administration (MSHA) and the U.S. Geological Survey (USGS) are cited here because of their existing responsibilities related to the U.S. minerals industry. The MSHA has responsibilities with respect to the oversight and regulation of all U.S. mines, including collecting information on blasting and mining collapses. MSHA already surveys all U.S. mines on a quarterly basis. The USGS, which is a scientific and technical agency with no regulatory or land management responsibilities, monitors all seismic events in the country, including mine blasts, and currently has an agreement with the Department of Defense to provide CTBT-related data on U.S. mine blasts and events. The USGS also surveys mines annually, and its most recent survey included requests for information on blasts over 300 metric tons; there is no equivalent international survey.
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--> An additional role of the technical agency would be to gather, for any calibration shots, the arrival time and seismograms from all available seismometers, including those not in the IMS, and make those data available to the policy agency for possible transmittal to the CTBTO. Additional Benefits In addition to the monitoring benefits, those countries that participate in the voluntary calibration efforts will be better able to respond to questions of consultation and clarification; only the mining operation that emitted the signal of concern need be contacted. Without calibration, the location error ellipse for a particular seismic event may contain many mines, all of which would likely have to be contacted. Calibration of travel-time models will also result in a substantial increase in the understanding of crustal structure and velocity, and improvement in earthquake locations in areas where local networks do not exist.
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