BULLETIN NUMBER 11 TABLE OF CONTENTS Page Introduction 1 Southeastern United States Seismicity 9 Notice of Availability of SEUSSN BULLETIN 10A: 9 LISTING OF HYPOCENTERS FROM SOUTHEASTERN U.S. SEISMIC NETWORK BULLETINS 1-10 (7/l/77-6/30/82) Notice of Special Reports of Interest: 9 1. THE GREENBACK, TENNESSEE EARTHQUAKES OF 24 SEPTEMBER 1982 AND THEIR TECTONIC ASSOCIATIONS 2. SEISMOGRAPHIC NETWORKS: PROBLEMS AND OUTLOOK FOR THE 1980s 10 List of Figures 1. Seismic Stations Operating During the Period July - December 1982 3 2. South Carolina Seismic Network 4 3. Virginia Tech Seismic Network 5 4. Georgia Tech Seismic Network 6 4. Alabama Seismic Network 7 6. Tennessee-North Carolina Seismic Network 8 7. Earthquake Epicenters for the Report Period 12 8. Earthquake Epicenters for the Period July 1977 - December 1982 13 List of Tables 1. Seismic Stations Operating During Report Period 14 2. Earthquakes During Report Period 17 Acknowledgments 35 Errata and Addenda 35 Appendix - Station Information 36 Seismic Stations in Alabama 36 Seismic Stations in Florida 37 Seismic Stations in Georgia 38 Seismic Stations in Mississippi 46 Seismic Stations in North Carolina 47 Seismic Stations in South Carolina 52 Seismic Stations in Tennessee 62 Seismic Stations in Virginia and West Virginia 67 Seismic Stations in West Virginia 87 Mailing List 91 INTRODUCTION This report is the eleventh semi-annual BULLETIN OF SEISMICITY OF THE SOUTHEASTERN UNITED STATES. It covers the period July through December, 1982. The organizations supplying data for this BULLETIN are the Carolina Power and Light Company, the E. I. DuPont de Nemours and Company, Inc. (Savannah River Laboratory), University of Florida, Georgia Institute of Technology, Georgia Southwestern College, Memphis State University (Tennessee Earthquake Information Center), South Carolina Electric and Gas Company, Tennessee Valley Authority, Union Carbide Corporation (Nuclear Division), United States Geological Survey, Virginia Division of Mineral Resources, Virginia Polytechnic Institute and State University (Seismological Observatory), Washington and Lee University and West Virginia University. Table 1 is a listing, by state, of the 111 stations operating during the period July-December, 1982. The format of the information included in the table is as follows: 1. Three or four letter station code, 2. Station latitude in decimal degrees, north, 3. Station longitude in decimal degrees, west, 4. Station elevation, meters, 5. Geographic name of station, 6. Station operator. Figure 1 is a geographic map of the entire Southeastern United States Seismic Network (SEUSSN). Figures 2, 3, 4 and 6 show the South Carolina, Virginia, Alabama-Georgia and Tennessee-North Carolina Networks, respectively. Each of those networks has station spacings too small to be shown clearly on Figure 1. Table 2 is a listing of the hypocentral parameters, phase arrival times and magnitude estimates for earthquakes that occurred in the southeastern United States during the report period. Most items in the listing are self-explanatory and all times are Coordinated Universal Time. Some entries that might require definition are: AZ= Epicenter-to-station azimuth in degrees, DIST= Epicentral distance in degrees (deg) or kilometers (km), DPTH= Focal depth estimate in km; FXD indicates that the depth was held fixed during the epicentral determination, GAP= The largest sector, in degrees, where there were no observing stations (HYPO71), HOR SEMI-AXES (KM, DEG)= Lengths (km) and azimuths (deg) of principal axes (horizontal projection) of error ellipsoid (HYPOELLIPSE; J. C. Lahr, USGS Open File Report 79-431), MBN= Body wave magnitude determination using Nuttli's formulas for the Lg phase, MEUS= Body wave magnitude determination using Evernden's formula for the Pn phase, ML= Local magnitude; contact agency or group making the estimate for details on their specific procedure, MLD= Local magnitude determined from duration of vibrations, MSZ= Surface wave magnitude determined from the long period vertical seismogram, NO= Number of phases used in the hypocenter determination, Q= Solution quality of error ellipsoid based on length of largest semi-axis (HYPOELLIPSE), or Solution quality of the hypocenter (HYPO71), RES= P wave residual in seconds; observed arrival time - calculated arrival time, RMS= Root mean square error of time residuals in sec (HYPO71), S-P= Arrival time of S-wave minus arrival time of P-wave in seconds, SQD= Solution and station distribution quality as defined in HYPO71, VERT SEMI-AXIS (KM)= Length (km) of principal vertical axis of error ellipsoid (HYPOELLIPSE). *XXXX= Agency or group that made the hypocentral determination. This BULLETIN contains a Station Information Appendix that gives detailed information on the operators, type of seismographs, response characteristics, recording formats, etc. Future BULLETINS will not repeat this information, but will present only changes, additions and deletions. SOUTHEASTERN UNITED STATES SEISMICITY Figure 7 is an epicenter map for the report period, July 1 - December 31, 1982, while Figure 8 is a cumulative epicenter map for the 5> year period from July 1, 1977, through December 31, 1982. There were 32 earthquakes (0.7 le M le 3.5) located by SEUSSN in the southeastern United States during the last six months of 1982. Of those, 2 in Tennessee and 1 in Alabama were felt events. The activity was well distributed throughout the region: 1 in Alabama, 5 in Georgia, 1 in North Carolina, 1 in Virginia and 24 in Tennessee. Additionally, 14 earthquakes were detected, but not located, in South Carolina. NOTICE OF AVAILABILITY OF SEUSSN BULLETIN 10A: LISTING OF HYPOCENTERS FROM SOUTHEASTERN U.S. SEISMIC NETWORK BULLETINS 1-10 (7/l/77-6/30/82) We have prepared a listing of all earthquakes from SEUSSN BULLETINS 1 through 10. In reviewing the earthquakes listed in the individual publications, some hypocentral and error parameters were changed. Those changes were derived from the following: 1. Relocation of some North Carolina and Tennessee earthquakes because of the significant amount of "Additional Data" not employed in the original locations 2. Conversion of error ellipsoid parameters to horizontal and vertical projection for some South Carolina shocks 3. Results of special relocation studies for most Virginia earthquakes 4. Correction of typographical errors The listing is entitled Southeastern U.S. Seismic Network Bulletin 10A - LISTING OF HYPOCENTERS FROM SOUTHEASTERN U.S. SEISMIC NETWORK. It is available upon request in hard copy or magnetic tape format. Please send a blank tape for us to write the listing file onto if you wish that format. NOTICE OF SPECIAL REPORT: THE GREENBACK, TENNESSEE EARTHQUAKES OF 24 SEPTEMBER 1982 AND THEIR TECTONIC ASSOCIATIONS The above 32-page report has been published by the Tennessee Earthquake Information Center as TEIC SPECIAL REPORT #9. It is authored by Don Reinbold and Joe Cornwell and dated March, 1983. The Summary from page one of the report is quoted below. 1) Two earthquakes, magnitudes 3.2 and 3.5, occurred 22 minutes apart near Greenback, Tennessee on 24 September 1982. 2) Aftershock monitoring by TVA and TEIC commenced less than 3 hours after the main shock. A total of 25 possible aftershocks were recorded during the period of 24 September (22:24) to 1 December; 7 occurred prior to installation of the aftershock monitoring equipment, 16 during operation of the array (all but 2 were recorded on one or more portable stations), and 3 subsequent to the removal of the temporary stations. Of this total, only 4 aftershocks were sufficiently well recorded to locate. 3) A reasonably well constrained composite focal mechanism of the two larger events was possible; it showed north/northeast and east-west striking nodal planes, consistent with a regional northeast-southwest maximum horizontal compressive stress. 4) Both of the two larger events were felt over more than a 6000 sq km area of eastern Tennessee. Maximum Modified Mercalli Intensities were IV and V, respectively. Two cases of slight damage were noted for the M3.5 event. 5) The Greenback area has probably experienced historic seismic activity, but demographic bias has led to these events being attributed to the Maryville area. 6) Geographical distribution of both historic and instrumental epicenters in eastern Tennessee suggest 2 lineations, NE-SW and E-W. The NE-SW lineation is approximately coincident with a seismogenic zone suggested by the U.S. Geological Survey that includes the Greenback area. 7) Both seismic and geologic data suggest similarities between the Greenback activity and the two most seismically active localities in the southern Appalachians -- Giles County, Virginia and Maryville, Tennessee. NOTICE OF SPECIAL REPORT: SEISMOGRAPHIC NETWORKS - PROBLEMS AND OUTLOOK FOR THE 1980s The above report was issued recently by the Committee on Seismology of the National Research Council. It is available from: Geological Sciences Board, National Research Council, 2101 Constitution Avenue, Washington, DC 20418 (no cost indicated). The Executive Summary (deleting the first two paragraphs which are directed toward nonspecialists) is quoted below. The large number of questions on seismographic networks brought in recent months to the Committee on Seismology is strong evidence that there are critical problems with network operations. At the Workshop on Seismographic Networks, prompted by these questions, participants considered global, regional, and national networks collectively as an integrated system and also as entities with specific problems. This report discusses each component of the system in terms of rationale and problems, giving recommendations for solutions. A brief statement follows of major problems and major recommendations for the global, regional, and national networks. Global Networks. Global networks are expected to provide for the scientific community a data base that continues indefinitely. Unfortunately, managing agencies find it difficult to recognize this long-term scientific importance. The service function of the networks, i.e., providing data for other users, must be considered in funding decisions by the managing agency. Global networks require continuing financial support at an adequate level. It is recommended (1) that consideration be given to transferring management responsibility for the global network from its present organizational base to another location within the U.S. Geological Survey or even to another agency, if such a change seems clearly advantageous; (2) that stable funding for global networks be sought from normal budgetary requests from within the U.S. Geological Survey, from the Defense Advanced Research Projects Agency, and from other agencies that use data from the networks; (3) that access to digital data and use of those data be improved while networks continue to meet fully the demand for and the global coverage provided by analog (i.e., visible) data at the present time; and (4) that procedures be established and funding be provided for the orderly and continuing interagency transfer of the most recent instrumentation and technology. Regional Networks. Regional network operations are beset with problems falling into three categories: functional definition, funding difficulties, and operational problems. Functional definition is the planned lifetime of a network, and a realistic estimate of it needs to be provided. Funding difficulties are of two types: a lack of stability on a year-to-year basis, and the vulnerability of research funding being decreased to maintain network operations in times of fiscal stress when research funding is mixed with basic operational costs of the network. Operational problems are seen in a lack of coordination among networks, the need for a more standardized data base management system, and a growing obsolescence of network equipment. These problems are interrelated and difficult to order in importance. Recommendations are (1) that networks of planned, limited lifetime be reviewed every three to five years with respect to objectives and performance; (2) that the provision of data fundamental to research on seismotectonic processes and earthquake occurrence in the region be acknowledged by funding agencies as the main purpose of regional networks; (3) that an adequate data set from all regional networks be archived; (4) that data formats be standardized; and (5) that operations of networks be coordinated. National Network. The concept of a national network lacks general acceptance and widespread support by the U.S. seismological community, within which there is at present little coordination of network operations. The concept is sound, and support will grow with formulation of a suitable plan for implementation. Working Group on Seismic Networks. It is recommended that a Working Group on Seismic Networks be set up under the Committee on Seismology to provide continuity and uniformity in consideration of the various policy matters arising in network seismology. This group will provide the review functions recommended throughout this report for global, regional, and national networks. It should evaluate continually the health and status of regional networks, and advise on the development of a national network. The contributions to the earth sciences from seismic networks of all types have been substantial in the past two decades. We have entered the 1980s with major advances in data acquisition, management, and processing techniques now available to seismology. The challenge is to build effectively on the present structure of networks, creating a new capability for addressing the next level of difficulty in the exciting problems of geoscience. TABLE 1 LIST OF OPERATING SEISMIC STATIONS BY STATE JULY - DECEMBER, 1982 STA LAT. LONG. ELEV. ID DEG.(N) DEG.(W) M LOCALITY OPERATOR ALABAMA BKA 33.6339 87.9690 122 KENNEDY GIT-GSA HGA 34.2602 85.8464 384 COLLINSVILLE GIT-GSA HVA 34.0264 86.7692 195 HANCEVILLE GIT-GSA MLA 32.7055 87.6936 55 SAWYERVILLE GIT-GSA OCA 34.6138 86.4352 250 OWENS CROSSROADS GIT-GSA PWLA 34.980 88.064 204 PICKWICK LAKE TEIC TDA 33.5417 86.0247 181 TALLADEGA GIT-GSA TSA 33.2561 87.0675 180 TANNEHILL STATE PARK GIT-GSA FLORIDA GAI 29.6458 82.3394 51 GAINESVILLE UFL GEORGIA AMG 32.0594 84.2177 106 AMERICUS GSW ATL 33.4333 84.3375 272 ATLANTA GIT BBG 34.874 83.811 1355 BRASSTOWN BALD TEIC BEV 34.0893 82.7334 158 CLARK HILL RESERVOIR GIT CDG 34.6108 84.6667 332 CARTERS DAM GIT CH5 33.7332 82.3118 114 CLARK HILL RESERVOIR GIT CH6 33.8938 82.5291 130 CLARK HILL RESERVOIR GIT CRG 34.6589 84.5821 422 CARTERS DAM GIT EP1 33.9514 82.5136 134 CLARK HILL RESERVOIR GIT IVA 34.2721 82.7460 168 CLARK HILL RESERVOIR GIT LDV 34.1479 82.6833 162 CLARK HILL RESERVOIR GIT RCG 34.975 85.348 468 ROCK CITY TEIC RMG 34.3359 85.3160 337 ROCKY MOUNTAIN NET GIT SMG 34.3495 85.3463 314 ROCKY MOUNTAIN NET GIT TVG 34.3771 85.3023 323 ROCKY MOUNTAIN NET GIT MISSISSIPPI PGM 34.4667 90.1167 105 PLEASANT GROVE TEIC NORTH CAROLINA BENN 35.565 81.661 878 BENN KNOB TEIC BRBC 35.739 82.286 1976 MT. MITCHELL TEIC CEH 35.8908 79.0928 152 CHAPEL HILL UNC GFM 36.111 81.807 1726 GRANDFATHER MOUNTAIN TEIC PKNC 36.046 81.158 785 PORES KNOB TEIC RBNC 35.357 82.986 1829 RICHLAND BALSAM TEIC RNC 35.63 78.98 85 RALEIGH CPL TRYN 32.253 82.263 704 TRYON PEAK TEIC SOUTH CAROLINA ASH 32.6983 80.5500 3 ASHEPOO USGS BCS 32.9812 80.0717 5 BAPTIST COLLEGE USGS CCS 32.8162 80.2553 3 CAWCAW SWAMP USGS CHF 34.0247 82.5867 152 CALHOUN FALLS USGS COW 33.3842 80.7008 33 COW CASTLE CREEK USGS GPD 32.7517 80.6117 3 GREEN POND USGS HBF 32.9330 80.3780 10 HARTS BLUFF USGS JSC 34.2790 81.2580 120 JENKINSVILLE USGS LHS 34.4790 80.8080 120 LIBERTY HILL USGS MGS 32.8970 80.1408 3 MIDDLETON GARDENS USGS MTT 33.7513 81.6362 150 MONETTA USGS MR01 34.3319 81.2957 131 MONTICELLO RESERVOIR SCEG MR02 34.1930 81.2301 84 MONTICELLO RESERVOIR SCEG MR03 34.3514 81.4569 125 MONTICELLO RESERVOIR SCEG MR04 34.4287 81.2166 145 MONTICELLO RESERVOIR SCEG OSB 33.5472 80.8444 80 ORANGEBURG USGS PBF 32.8628 79.7607 -68 PORCHER BLUFF USGS PBS 33.2790 80.2640 25 PIGEON BAY USGS PPS 32.8237 80.0400 4 PIERPONT USGS PRM 34.0833 82.3633 170 PARSONS MOUNTAIN USGS SBK 32.5672 80.1803 -68 SEABROOK USGS SGS 33.1930 80.5120 25 ST GEORGE USGS SRPD 33.1550 81.7125 31 SAVANNAH RIVER LAB DUP SRPN 33.3290 81.5888 95 SAVANNAH RIVER LAB DUP SRPW 33.2023 81.5782 77 SAVANNAH RIVER LAB DUP SVS 32.9688 80.2487 3 SLANDSVILLE USGS TRK 33.1221 79.7778 10 TURKEY CREEK USGS VEW 32.7177 79.9415 -68 OCEANVIEW USGS VRN 33.0375 80.9417 30 VARNEVILLE USGS ZIN 33.1072 80.1628 10 MT ZION CHURCH USGS TENNESSEE BHT 35.847 84.945 826 BLOWHOLE TEIC CBT 35.5394 84.4206 357 CHRISTIANBURG GIT DCT 35.0542 84.4194 508 DUCKTOWN GIT EBZ 35.141 89.351 169 EBENEZER TEIC* ETT 35.326 84.455 588 ETOWAH TEIC GLT 36.362 86.498 159 GALLATIN VSCC/TEIC HPK 35.926 83.879 305 KNOXVILLE TVA/GIT/TEIC HWR 35.758 83.938 311 MARYVILLE TVA/TEIC MPH 35.123 89.932 94 MEMPHIS TEIC* ORT 35.9095 84.3048 370 OAK RIDGE UCC RCT 35.3453 84.6614 265 RICEVILLE GIT RHT 35.0781 84.8825 299 RED HILL GIT SFTN 35.3575 90.0188 -23 SHELBY FOREST TEIC* SMTN 36.382 83.182 768 SHORT MOUNTAIN TEIC TKL 35.6581 83.7742 350 TUCKALEECHEE CAVERNS TEIC TLT 35.3011 84.2833 512 TELLICO PLAINS GIT UTM 36.290 88.941 108 UNIV. TN. MARTIN UTM/TEIC *In western Tennessee near the New Madrid Seismic Zone- not in southeastern United States VIRGINIA BAV 37.2220 80.4250 622 BLACKSBURG VPI BLA 37.2114 80.4211 634 BLACKSBURG VPI BV1 38.1781 79.6611 768 BATH COUNTY VPI BV2 38.1367 79.9194 610 BATH COUNTY VPI BV3 38.2383 79.7667 750 BATH COUNTY VPI CBN 38.2050 77.3733 70 CORBIN USGS CCVA 36.602 83.667 509 CUDJO CAVERNS TEIC CNV 38.2050 77.3733 70 CORBIN VPI CVL 37.9813 78.4608 167 CHARLOTTESVILLE VPI CVV 37.9814 78.4608 167 CHARLOTTESVILLE DMR FRV 37.2030 78.3593 216 FARMVILLE VPI FTV 38.8661 78.1688 341 FRONT ROYAL DMR GHV 37.7942 78.1073 107 GOOCHLAND VPI LEX 37.7894 79.4417 311 LEXINGTON WAL MSH 37.1150 80.4012 684 CHRISTIANSBURG VPI NAV 37.3167 80.7931 610 NARROWS VPI NA2 38.1270 77.7470 82 NORTH ANNA VPI NA5 37.9930 77.7470 76 NORTH ANNA VPI NA11 37.9830 77.6850 84 NORTH ANNA VPI NA12 37.9830 77.8795 125 NORTH ANNA VPI PBV 36.9823 77.5312 49 PETERSBURG VPI PLVA 36.666 81.161 1353 POINT LOOKOUT TEIC PUV 37.0235 80.8158 652 PULASKI VPI VBV 36.7853 76.1080 5 VIRGINIA BEACH TCC VWV 37.4660 80.3917 963 VA-WVA BORDER VPI WMV 37.1085 80.9705 1157 WALKER MOUNTAIN VPI WEST VIRGINIA BV4 38.3572 79.8278 814 POCAHONTAS COUNTY VPI GBV 38.43212 79.84531 802 GREEN BANK NASA HWV 37.5905 80.8408 521 HINTON VPI MRG 39.6331 79.9544 281 MORGANTOWN WVU PWV 37.3348 81.0488 820 PRINCETON VPI OPERATOR CODE CPL - Carolina Power and Light Company, NC DMR - Virginia Division of Mineral Resources, VA DUP - E. I. DuPont de Nemours and Company, Inc., SC NASA - National Aeronautics and Space Administration/ Goddard Space Flight Center, WV GIT - Georgia Institute of Technology, GA GSA - Geological Survey of Alabama, AL GSW - Georgia Southwestern College, GA SCEG - South Carolina Electric and Gas Company, SC TCC - Tidewater Community College, VA TEIC - Tennessee Earthquake Information Center, TN TVA - Tennessee Valley Authority, TN UCC - Union Carbide Corporation, TN UFL - University of Florida, FL UNC - University of North Carolina, NC USGS - United States Geological Survey, CO UTM - University of Tennessee at Martin, TN VPI - Virginia Tech, VA VSCC - Volunteer State Community College, TN WAL - Washington and Lee University, VA WVU - West Virginia University, WV TABLE 2 LIST OF SOUTHEASTERN UNITED STATES EARTHQUAKES FOR THE TIME PERIOD 1 JULY 1982 THROUGH 31 DECEMBER 1982 8 JULY 1982 CALDERWOOD, TENNESSEE ML= 1.4 (GIT) *GIT LAT= 35.471N LONG= 84.116W H= 05-18-50.6 DPTH= 0.0 KM, FXD ERROR ELLIPSE (DERIVED FROM HYPO71): SEMI-MAJOR AXIS= 2.0 KM SEMI-MINOR AXIS= 1.5 KM AZ OF MAJOR AXIS= 113 DEG AREA OF ELLIPSE= 9 SQ KM STA PHASE TIME DIST (KM) AZ (DEG) RES (SEC) CBT PLG 05-18-56.6 28.6 285 0.85 SLG -59.8 -0.06 ETT PLG -56.3 34.7 242 -0.45 SLG -19-00.4 -1.16 TKL PLG -18-58.0 37.4 56 0.81 SLG -19-01.3 -1.00 DCT PLG -00.6 53.8 211 0.69 SLG -07.2 0.27 BBG PLG -03.2 71.8 157 0.32 SLG -11.7 -0.28 5 SEPTEMBER 1982 ETOWAH, TENNESSEE ML= 3.2 (GIT) *TEIC LAT= 35.20N LONG= 84.51W H= 10-11-09.4 DPTH= 13.4 KM NO=21, RMS RES=0.13 SEC, GAP=79 DEG, ERH=0.4 KM, ERZ=0.5 KM, Q=B, SQD=A/B (See TEIC listing page 32) *GIT LAT= 35.203N LONG= 84.521W H= 10-11-09.2 DPTH= 0.0 KM, FXD ERROR ELLIPSE (DERIVED FROM HYPO71): SEMI-MAJOR AXIS= 1.3 KM SEMI-MINOR AXIS= 1.0 KM AZ OF MAJOR AXIS= 114 DEG AREA OF ELLIPSE= 4 SQ KM STA PHASE TIME DIST (KM) AZ (DEG) RES (SEC) DCT PG 10-11-13.2 18.9 151 0.58 S -15.6 0.46 RHT PG -16.0 35.7 247 0.32 S -20.2 -0.23 BBG PLG -22.1 74.2 119 0.25 SLG -30.2 -1.03 BHT PLG -23.4 81.2 332 0.39 SLG -33.4 0.20 TKL PLG -23.6 84.7 53 0.02 SLG -34.0 -0.17 HPK PLG -25.8 99.2 36 -0.19 SLG -37.5 -0.76 HGA PLG -37.2 159.7 229 1.22 SLG -56.1 0.86 OCA PLG -11-41.2 186.2 250 0.85 SLG -12-01.5 -1.17 IVA PLG -11-43.0 191.8 122 1.72 SLG -12-03.2 -1.05 TDA PLG -11-47.8 229.6 217 0.28 SLG -12-13.7 -1.16 HVA PLG -11-49.6 242.8 238 -0.11 SLG -12-17.3 -1.28 20 SEPTEMBER 1982 CENTRAL VIRGINIA, NEAR DOSWELL, VA MD= 1.5 (VPI) *VPI LAT= 37.822N LONG= 77.496W H= 12-15-32.0 DPTH= 10.6 KM NO= 20, RMS RES= 0.18 SEC, GAP= 168 DEG, ERH= 0.9 KM, ERZ= 1.5 KM, Q= C HYPOELLIPSE SEMI-AXES (LENGTH IN KM, AZIMUTH IN DEG): HORIZONTALS ARE 0.6, 2; 0.9, -88 AND THE VERTICAL IS 1.5 KM. QUALITY= A. STA PHASE TIME DIST (KM) AZ (DEG) RES (SEC) NA11 EP 12-15-36.57 24.4 317 0.20 S -39.60 0.03 NA5 EP -37.42 29.1 311 0.33 S -40.99 0.18 NA12 IPD -38.63 38.2 298 0.12 S -43.31 0.04 NA2 IPC -38.83 40.4 327 -0.03 S -43.48 -0.39 CNV EP -39.45 43.9 14 0.04 S -44.46 -0.37 GHV IPD -41.02 53.9 267 -0.00 S -47.60 -0.02 CVL EP -46.23 86.7 282 -0.12 S -56.55 -0.28 PBV EP -47.73 93.2 182 0.34 S -58.51 -0.13 FRV EP -48.73 102.7 228 -0.20 S -16-01.41 0.12 FTV P -15-53.10 129.9 333 -0.04 S -16-08.7 0.13 ADDITIONAL DATA CVV IPG 12-15-46.2 SG -56.2 LEX ES -20 This event occurred roughly 30 km north of Richmond, Virginia, and 30 km southeast of the North Anna Power Plant (approximately 24 km southeast of network station NA11, the closest station). Of particular interest is that this is the third event in five months to have been located in this area. The two previous events in this area, #82 and #86 (reported in SEUSSN Bulletin No. 10) are located 8.1 km and 1.2 km (respectively) northwest of this latest event. These events have computed duration magnitudes of between 2.1 (#82; felt) and 1.5 (#87). Times of occurrence have been 07h, 12h and 23h UTC. Computed focal depths range from 10 km (#82) to 13 km (#86) with an average nearest station distance-to-computed focal depth ratio of approximately 2-to-1. Thus, these focal depths are reasonably well-constrained. That fact, coupled with the repeated conversations with all known quarry operators in the area, leads us to believe that these are natural tectonic events. 21 SEPTEMBER 1982 KNOXVILLE, TENNESSEE MLD= 1.6 (TEIC), ML= 2.0 (GIT) *TEIC LAT= 36.10N LONG= 83.73W H= 01-07-18.4 DPTH= 17.0 KM NO=20, RMS RES=0.13 SEC, GAP=242 DEG, ERH=0.6 KM, ERZ=1.2 KM, Q=C, SQD=A/D (See TEIC listing page 33) *GIT LAT= 36.053N LONG= 83.712W H= 01-07-18.3 DPTH= 0.0 KM, FXD ERROR ELLIPSE (DERIVED FROM HYPO71): SEMI-MAJOR AXIS= 1.5 KM SEMI-MINOR AXIS= 0.9 KM AZ OF MAJOR AXIS= 145 DEG AREA OF ELLIPSE= 4 SQ KM STA PHASE TIME DIST (KM) AZ (DEG) RES (SEC) CBT PLG 01-07-32.9 85.6 228 0.05 SLG -43.5 -0.04 TLT PLG -34.9 98.0 212 -0.01 SLG -47.2 0.16 DCT PLG -39.8 127.8 210 -0.04 SLG -55.3 -0.12 24 SEPTEMBER 1982 KNOXVILLE, TENNESSEE MBN= 3.0 (BLA), 3.2 (TEIC) *USGS LAT= 35.687N LONG= 84.244W H= 21-57-42.4 DPTH= 10.3 KM, FXD (Felt (V) at Alcoa, Knoxville and Mt. Vernon, Tennessee) STA PHASE TIME DIST (KM) AZ (DEG) RES (SEC) RSCP EP 21-58-02.2 122.3 266 -0.8 PRM EP -20.7 246.8 135 0.9 NAV EP -36.2 358.0 59 -0.8 BLA EP -36.5 382.5 63 -0.6 CVL E(P) -58.5 574.8 62 -3.2 *TEIC LAT= 35.68N LONG= 84.24W H= 21-57-42.4 DPTH= 14.3 KM NO=25, RMS RES=0.15 SEC, GAP=61 DEG, ERH=0.4 KM, ERZ=0.6 KM, Q=B, SQD=A/B (See TEIC listing page 33; Max intensity= IV MMI) *GIT LAT= 35.669N LONG= 84.253W H= 21-57-42.0 DPTH= 0.0 KM, FXD ERROR ELLIPSE (DERIVED FROM HYPO71): SEMI-MAJOR AXIS= 1.6 KM SEMI-MINOR AXIS= 1.0 KM AZ OF MAJOR AXIS= 121 DEG AREA OF ELLIPSE= 5 SQ KM STA PHASE TIME DIST (KM) AZ (DEG) RES (SEC) CBT PG 21-57-47.0 20.9 227 1.21 TLT PLG -50.0 40.8 184 0.86 SLG -55.5 0.84 ETT PLG -50.1 42.2 206 0.74 SLG -55.3 0.27 TKL PLG -49.9 43.4 92 0.34 SLG -55.4 0.03 HPK PLG -49.7 44.3 50 -0.02 SLG -55.3 -0.34 RCT PLG -51.5 51.5 226 0.60 SLG -58.7 1.04 BHT PLG -53.7 65.7 288 0.44 DCT PLG -55.0 69.8 192 1.08 SLG -58-04.0 1.21 RHT PLG -57-57.0 86.8 221 0.26 SLG -58-07.2 -0.38 BBG PLG -57-58.6 96.8 155 0.21 SLG -58-10.1 -0.27 CRG PLG -01.5 115.9 195 -0.04 SLG -14.2 -1.54 TVG PLG -10.2 171.9 214 -0.60 IVA PLG -15.9 206.4 138 -0.61 SLG -40.5 -0.67 HGA PLG -17.1 212.6 223 -0.44 SLG -41.8 -1.12 OCA PLG -19.8 229.6 240 -0.54 TDA PLG -28.7 285.2 215 -0.84 HVA PLG -30.1 291.7 232 -0.50 SLG -59-03.9 -1.22 ADDITIONAL DATA CVV PN 21-59-10 SN 22-00-22 FTV PN 22-00-38 PRM IP 21-58-20.8 ES -49.5 SVS EP -21.6 24 SEPTEMBER 1982 KNOXVILLE, TN MBN= 3.4 (BLA), 3.5 (TEIC), ML=3.5 (GIT) *USGS LAT= 35.689N LONG= 84.247W H= 22-19-16.9 DPTH= 10.2 KM, FXD (Felt (V) at Alcoa, Maryville and Mt. Vernon, Tennessee) STA PHASE TIME DIST (KM) AZ (DEG) RES (SEC) RSCP EP 22-19-36.8 121.2 266 -0.7 PRM EP -54.8 248.0 135 0.4 NAV EP -20-07.6 358.0 59 -0.9 BLA EP -10.8 382.5 63 -0.8 CVL E(P) -34.0 574.8 62 -2.2 NA12 EP -40.0 622.7 64 -2.2 *TEIC LAT= 35.69N LONG= 84.25W H= 22-19-16.9 DPTH= 10.5 KM NO=25, RMS RES=0.12 SEC, GAP=63 DEG, ERH=0.3 KM, ERZ=0.5 KM, Q=B, SQD=A/C (See TEIC listing page 33; Max intensity= IV MMI) *GIT LAT= 35.670N LONG= 84.282W H= 22-19-16.5 DPTH= 0.0 KM, FXD ERROR ELLIPSE (DERIVED FROM HYPO71): SEMI-MAJOR AXIS= 2.0 KM SEMI-MINOR AXIS= 1.1 KM AZ OF MAJOR AXIS= 124 DEG AREA OF ELLIPSE= 7 SQ KM STA PHASE TIME DIST (KM) AZ (DEG) RES (SEC) TLT PLG 22-19-24.7 40.9 180 1.07 SLG -30.2 1.04 ETT PLG -24.6 41.2 202 0.92 TKL PLG -24.5 46.0 92 0.03 SLG -30.1 -0.50 HPK PLG -24.2 46.3 52 -0.31 SLG -29.8 -0.86 RCT PLG -26.0 49.8 224 0.91 SLG -33.2 1.56 BHT PLG -28.2 63.1 288 0.90 DCT PLG -29.3 69.4 190 0.96 S-P -09.0 -0.24 RHT PLG 20-19-31.4 85.2 220 0.45 S-P -10.2 -1.14 BBG PLG 22-19-33.2 98.1 154 0.12 SLG -45.1 -0.12 CRG PLG -36.1 115.4 194 0.16 SLG -48.9 -1.18 TVG PLG -44.4 170.6 213 -0.66 SLG -20-04.0 -1.58 HGA PLG -19-51.9 211.0 223 0.17 SLG -20-16.5 -0.42 OCA PLG -19-54.1 227.4 239 -0.35 SLG -20-21.2 -0.34 HVA PLG -04.2 231.6 232 -0.55 SLG -37.6 -1.44 ADDITIONAL DATA CVV PN 22-20-35 PG -47 SN -21-45 FTV PN -20-57 -22-15 PRM EP 22-19-54.5 ES -20-25.5 LEX EP -19-27 ELG -20-36 24 SEPTEMBER 1982 LENOIR CITY, TENNESSEE ML=1.5 (GIT) *TEIC LAT= 35.68N LONG= 84.25W H= 22-54-11.7 DPTH= 6.6 KM NO=11, RMS RES=0.09 SEC, GAP=167 DEG, ERH=0.3 KM, ERZ=1.3 KM, Q=B, SQD=A/C (See TEIC listing page 33) *GIT LAT= 35.661N LONG= 84.226W H= 22-54-11.8 DPTH= 10.8 KM ERROR ELLIPSE (DERIVED FROM HYPO71): SEMI-MAJOR AXIS= 1.3 KM SEMI-MINOR AXIS= 0.4 KM AZ OF MAJOR AXIS= 122 DEG AREA OF ELLIPSE= 1.7 SQ KM STA PHASE TIME DIST (KM) AZ (DEG) RES (SEC) CBT S-P -03.3 24.8 232 -0.00 TLT PLG 22-54-19.1 40.3 187 0.21 SLG -24.6 0.26 TKL PLG -19.1 41.0 90 0.11 SLG -24.4 -0.12 ETT PLG -19.2 42.5 209 -0.07 SLG -24.8 -0.18 RCT PLG -20.9 52.7 228 -0.05 S-P -07.2 0.32 9 OCTOBER 1982 BENTON, TENNESSEE ML=1.8 (GIT) *GIT LAT= 35.148N LONG= 84.685W H= 18-09-53.7 DPTH= 0.0 KM, FXD ERROR ELLIPSE (DERIVED FROM HYPO71): SEMI-MAJOR AXIS= 1.3 KM SEMI-MINOR AXIS= 1.0 KM AZ OF MAJOR AXIS= 109 DEG AREA OF ELLIPSE= 4 SQ KM STA PHASE TIME DIST (KM) AZ (DEG) RES (SEC) RHT S 18-09-59.8 19.6 247 -0.09 RCT S -10-00.9 22.0 6 0.24 DCT PLG -09-58.4 26.3 113 -0.08 SLG -10-02.7 0.38 TLT SLG -05.8 40.4 65 -0.47 31 OCTOBER 1982 GA-AL BORDER MBN=2.9 (USGS), MLD=2.9 (TEIC), ML=3.0 (GIT) *USGS LAT= 32.658N+-6.8 KM LONG= 84.906W+-3.2 KM H= 03-07-39.5 DPTH= 5.0 KM, FXD (Felt (V) at Ellerslie and Midland, Georgia) STA PHASE TIME DIST (KM) AZ (DEG) RES (SEC) TDA P 03-08-01.9 143.4 313 -1.9 TSAL P -12.9 212.4 289 -0.1 OCA P -19.9 259.1 327 0.8 S -50.5 *GIT LAT= 32.671N LONG= 84.873W H= 03-07-36.7 DPTH= 0.0 KM, FXD ERROR ELLIPSE (DERIVED FROM HYPO71): SEMI-MAJOR AXIS= 2.3 KM SEMI-MINOR AXIS= 1.1 KM AZ OF MAJOR AXIS= 104 DEG AREA OF ELLIPSE= 8 SQ KM STA PHASE TIME DIST (KM) AZ (DEG) RES (SEC) TDA PLG 03-08-02.0 144.9 312 0.94 SLG -19.4 0.79 HGA PLG -11.5 198.4 333 1.58 TSA PLG -12.6 215.8 288 -0.19 SLG -38.5 -0.04 CRG PLG -15.0 222.1 7 1.18 SLG -41.1 0.80 HVA PLG -15.7 232.9 311 0.10 SLG -43.2 -0.12 BEV PLG -19.8 254.9 52 0.55 SLG -49.0 -0.52 OCA PLG -20.3 260.5 326 0.12 SLG -50.8 -0.30 MLA PLG -19.7 264.6 271 -1.16 RHT PLG -20.5 266.9 360 -0.73 SLG -52.4 -0.49 IVA PLG -21.2 267.0 48 -0.05 SLG -52.6 -0.32 RCT PLG -26.4 297.2 4 0.16 SLG -09-00.5 -0.90 BKA SLG -04.0 309.4 290 -0.83 CBT SLG -07.5 320.9 7 -0.55 --Information purposes only--see TEIC listing page 33-- *TEIC LAT= 32.49N LONG= 84.95W H= 03-07-37.5 DPTH= 16.0 KM NO= 14, RMS RES= 0.16 SEC, GAP= 323 DEG, Q= D, SQD= D/D 31 OCTOBER 1982 GA-AL BORDER MBN=3.1 (USGS), ML=3.1 (GIT), MLD=3.0 (TEIC) *USGS LAT= 32.655N+-6.9 KM LONG= 84.867W+-3.4 KM H= 03-12-15.6 DPTH= 5.0 KM, FXD STD DEV RES= 0.8 SEC ON 16 OF 19 ARRIVAL TIMES (Felt in Harris and Muscogee Counties, Georgia, and Phenix City, Alabama) STA PHASE TIME DIST (KM) AZ (DEG) RES (SEC) TSAL PN 03-12-49.0 215.7 289 -0.6 ES -13-14.6 HVA PN -12-51.8 233.5 311 -0.1 ES -13-19.4 RCG IP -12-56.01 261.3 350 0.5 IS -13-28.1 OCA PN -12-55.8 261.3 327 0.3 ES -13-29.5 BBG EP -12-56.5 264.6 21 0.4 S -13-29.55 MLAL PN -12-56.1 264.6 272 0.1 ES -13-26.1 RHT PN -12-57.2 269.1 360 0.8 ES -13-29.4 PRM EP -12-58.4 281.3 55 0.3 ETT EP -13-00.73 299.1 7 0.4 IS -37.85 BKA PN -03.0 309.1 291 1.4 ES -39.5 RSCP EP -04.8 333.6 349 0.1 RBNC EP -06.4 346.9 30 -0.1 S -51.5 TKL EP -06.1 348.0 17 -0.4 ES -51.0 BHT EP -06.95 353.6 359 -0.4 (S) -53.2 PWLA E(P) -10.4 392.5 312 -1.8 GFM E(P) -22.0 475.9 35 -1.0 NAV EP -41.8 637.1 35 -1.6X BLA EP -42.8 648.2 38 -2.0X CVL E(P) -14-05.0 829.5 43 -2.7X *GIT LAT= 32.644N+-1.3 KM LONG= 84.894W+-2.2 KM H= 03-12-12.2 DPTH= 0.0 KM, FXD ERROR ELLIPSE (DERIVED FROM HYPO71): SEMI-MAJOR AXIS= 2.5 KM SEMI-MINOR AXIS= 1.2 KM AZ OF MAJOR AXIS= 108 DEG AREA OF ELLIPSE= 9 SQ KM STA PHASE TIME DIST (KM) AZ (DEG) RES (SEC) RHT PLG 03-12-57.2 270.0 0 -0.06 SLG -13-29.4 0.14 BKA PLG -03.0 308.7 291 -0.66 SLG -39.5 -0.65 MLA PLG -12-56.0 262.8 272 -0.07 SLG -13-26.1 -1.15 TSA PLG -12-49.0 215.0 288 0.84 SLG -13-14.6 0.78 HVA PLG -12-51.8 233.4 312 0.59 SLG -13-19.4 0.41 OCA PLG -12-55.8 262.0 327 -0.14 SLG -13-26.2 -0.83 IVA PLG -12-57.5 270.6 48 0.14 SLG -13-29.5 0.06 TDA SLG -12-55.5 145.5 314 1.19 BEV PLG -56.0 258.4 51 0.65 SLG -13-25.5 -0.52 RCT SLG -37.2 300.4 4 -0.61 CRG SLG -18.2 225.4 7 1.46 CBT SLG -43.0 324.2 8 -1.50 --Information purposes only--see TEIC listing page 33-- *TEIC LAT= 32.37N LONG= 84.97W H= 03-12-12.0 DPTH= 16.0 KM NO= 15, GAP= 324 DEG, Q= D, SQD= D/D 2 NOVEMBER 1982 MARYVILLE, TENNESSEE MLD= 1.3 (TEIC), ML= 2.2 (GIT) *TEIC LAT= 35.75N LONG= 83.96W H= 08-44-45.8 DPTH= 10.8 KM NO=9, RMS RES=0.08 SEC, GAP=141 DEG, ERH=0.4 KM, ERZ=1.0 KM, Q=B, SQD=A/C *GIT LAT= 35.743N LONG= 83.970W H= 08-44-45.8 DPTH= 0.0 KM, FXD ERROR ELLIPSE (DERIVED FROM HYPO71): SEMI-MAJOR AXIS= 0.7 KM SEMI-MINOR AXIS= 0.6 KM AZ OF MAJOR AXIS= 129 DEG AREA OF ELLIPSE= 1.3 SQ KM STA PHASE TIME DIST (KM) AZ (DEG) RES (SEC) TKL PG 08-44-49.8 20.1 118 0.34 S -52.3 0.17 HPK PG -49.8 21.9 22 0.00 S -52.5 -0.22 CBT PLG -54.0 46.6 241 0.08 S-P -06.2 0.00 ETT PLG 08-44-57.0 63.8 224 0.25 SLG -45-05.1 0.18 BHT SLG -11.9 88.9 278 -0.10 BBG SLG -13.7 97.5 171 -0.69 8 NOVEMBER 1982 ATHENS, TENNESSEE ML= 1.8 (GIT) *TEIC LAT= 35.42N LONG= 84.51W H= 09-56-10.0 DPTH= 25.4 KM NO=9, RMS RES=0.42 SEC, GAP=149 DEG, ERH=3.9 KM, ERZ=4.1 KM, Q=C, SQD=C/C (See TEIC listing page 33) *GIT LAT= 35.189N LONG= 84.356W H= 09-56-10.6 DPTH= 0.0 KM, FXD ERROR ELLIPSE (DERIVED FROM HYPO71): SEMI-MAJOR AXIS= 1.9 KM SEMI-MINOR AXIS= 1.0 KM AZ OF MAJOR AXIS= 49 DEG AREA OF ELLIPSE= 6 SQ KM STA PHASE TIME DIST (KM) AZ (DEG) RES (SEC) ETT PG 09-56-14.6 18.7 324 0.63 S -17.2 0.74 RCT S -21.2 34.4 300 -0.19 S-P -04.3 -0.27 CBT PLG 09-56-17.3 39.6 349 -0.22 SLG -22.1 -0.81 RHT SLG -25.9 51.3 256 -0.28 BBG PLG -21.2 59.2 126 0.44 SLG -28.1 -0.30 14 NOVEMBER 1982 GREENVILLE, TENNESSEE MLD= 2.4 (TEIC), ML= 2.8 (GIT) *TEIC LAT= 36.20N LONG= 82.87W H= 10-31-58.9 DPTH= 12.0 KM NO=23, RMS RES=0.14 SEC, GAP=118 DEG, ERH=0.4 KM, ERZ=0.7 KM, Q=B, SQD=A/C (See TEIC listing page 33) *GIT LAT= 35.970N LONG= 82.741W H= 10-31-59.1 DPTH= 0.0 KM, FXD ERROR ELLIPSE (DERIVED FROM HYPO71): SEMI-MAJOR AXIS= 3.5 KM SEMI-MINOR AXIS= 2.3 KM AZ OF MAJOR AXIS= 128 DEG AREA OF ELLIPSE= 25 SQ KM STA PHASE TIME DIST (KM) AZ (DEG) RES (SEC) TLT S-P -20.0 157.6 242 -0.98 CBT SLG 10-32-45.2 158.8 253 0.28 DCT PLG -29.0 182.3 236 -0.63 SLG -52.2 0.70 RCT PLG -30.0 186.6 248 -0.33 SLG -53.0 0.30 BEV S-P -28.0 208.6 180 0.24 CRG PLG 10-32-36.0 220.7 229 0.02 SLG -33-02.0 -0.30 TVG PLG -32-48.0 290.8 233 0.43 SLG -33-22.0 0.01 RMG PLG -32-47.7 294.6 233 -0.49 20 NOVEMBER 1982 BENTON, TENNESSEE ML= 1.1 (GIT) *GIT LAT= 35.220N LONG= 84.752W H= 03-30-44.7 DPTH= 0.0 KM, FXD ERROR ELLIPSE (DERIVED FROM HYPO71): SEMI-MAJOR AXIS= 0.9 KM SEMI-MINOR AXIS= 0.4 KM AZ OF MAJOR AXIS= 147 DEG AREA OF ELLIPSE= 1.2 SQ KM STA PHASE TIME DIST (KM) AZ (DEG) RES (SEC) RCT PG 03-30-47.5 16.1 31 -0.10 S -50.0 0.25 RHT PG -48.1 19.8 217 -0.17 S -51.0 0.09 DCT PLG -51.2 35.4 121 0.27 SLG -55.7 -0.13 CBT SLG -58.7 46.5 40 -0.23 23 NOVEMBER 1982 WALDENRIDGE, TENNESSEE ML= 2.0 (GIT) *GIT LAT= 35.068N LONG= 85.446W H= 04-51-00.1 DPTH= 0.0 KM, FXD ERROR ELLIPSE (DERIVED FROM HYPO71): SEMI-MAJOR AXIS= 2.9 KM SEMI-MINOR AXIS= 1.2 KM AZ OF MAJOR AXIS= 128 DEG AREA OF ELLIPSE= 11 SQ KM STA PHASE TIME DIST (KM) AZ (DEG) RES (SEC) TVG SLG 04-51-23.3 77.7 170 0.13 RCT PLG -14.1 77.8 67 0.70 SLG -22.9 -0.30 OCA SLG -30.0 103.4 241 -0.38 CBT PLG -19.0 107.1 61 0.76 SLG -31.0 -0.42 TLT SLG -31.5 109.1 76 -0.48 1 DECEMBER 1982 WALLAND, TENNESSEE ML= 2.0 (GIT) *GIT LAT= 35.775N LONG= 83.742W H= 02-06-23.7 DPTH= 0.0 KM, FXD ERROR ELLIPSE (DERIVED FROM HYPO71): SEMI-MAJOR AXIS= 3.4 KM SEMI-MINOR AXIS= 3.0 KM AZ OF MAJOR AXIS= 146 DEG AREA OF ELLIPSE= 33 SQ KM STA PHASE TIME DIST (KM) AZ (DEG) RES (SEC) CBT PLG 02-06-35.2 66.7 247 0.08 SLG -43.6 -0.04 TLT PLG -36.0 71.9 223 0.03 SLG -44.8 -0.28 DCT PLG -40.3 100.8 218 -0.45 SLG -53.7 0.50 1 DECEMBER 1982 ETOWAH, TENNESSEE ML= 2.4 (GIT) *TEIC LAT= 35.26N LONG= 84.43W H= 13-39-44.6 DPTH= 13.1 KM NO=11, RMS RES=0.08 SEC, GAP=107 DEG, ERH=0.4 KM, ERZ=0.6 KM, Q=B, SQD=A/B (See TEIC listing page 33) *GIT LAT= 35.253N LONG= 84.446W H= 13-39-45.0 DPTH= 0.0 KM, FXD ERROR ELLIPSE (DERIVED FROM HYPO71): SEMI-MAJOR AXIS= 1.0 KM SEMI-MINOR AXIS= 0.7 KM AZ OF MAJOR AXIS= 173 DEG AREA OF ELLIPSE= 2 SQ KM STA PHASE TIME DIST (KM) AZ (DEG) RES (SEC) ETT PG 13-39-47.3 8.2 354 0.86 TLT PG -47.9 15.7 70 0.09 S-P -02.2 0.11 DCT PG 13-39-49.0 22.2 174 0.01 S -51.8 -0.14 RCT PLG -49.2 22.2 298 0.18 SLG -52.3 -0.09 CBT PLG -50.3 31.8 4 -0.32 SLG -54.5 -0.60 RHT PLG -52.8 44.3 244 0.13 SLG -58.4 -0.19 6 DECEMBER 1982 KNOXVILLE, TENNESSEE MLD= 2.0 (TEIC), ML= 2.2 (GIT) *TEIC LAT= 36.13N LONG= 83.71W H= 10-52-34.9 DPTH= 10.6 KM NO=14, RMS RES=0.20 SEC, GAP=196 DEG, ERH=1.1 KM, ERZ=1.0 KM, Q=C, SQD=B/D (See TEIC listing page 33) *GIT LAT= 36.111N LONG= 83.754W H= 10-52-35.5 DPTH= 0.0 KM, FXD ERROR ELLIPSE (DERIVED FROM HYPO71): SEMI-MAJOR AXIS= 2.0 KM SEMI-MINOR AXIS= 1.4 KM AZ OF MAJOR AXIS= 58 DEG AREA OF ELLIPSE= 9 SQ KM STA PHASE TIME DIST (KM) AZ (DEG) RES (SEC) HPK PLG 10-52-40.0 23.4 209 0.27 SLG -43.4 0.17 TKL PLG -44.8 50.2 182 0.64 SLG -50.7 -0.07 CBT PLG -50.0 87.3 224 -0.29 SLG -53-01.5 0.32 TLT PLG -52-52.2 101.7 208 -0.47 SLG -53-05.0 -0.22 BHT SLG -08.0 111.2 255 0.11 DCT PLG -52-57.3 131.6 207 -0.32 SLG -53-13.5 -0.14 8 DECEMBER 1982 MACON, GEORGIA ML= 2.9 (GIT), MLD= 2.4 (TEIC) *GIT LAT= 32.982N LONG= 83.508W H= 23-36-56.3 DPTH= 0.0 KM, FXD ERROR ELLIPSE (DERIVED FROM HYPO71): SEMI-MAJOR AXIS= 3.1 KM SEMI-MINOR AXIS= 2.1 KM AZ OF MAJOR AXIS= 123 DEG AREA OF ELLIPSE= 20 SQ KM STA PHASE TIME DIST (KM) AZ (DEG) RES (SEC) BEV SLG 23-37-37.3 142.5 30 -0.25 LDV S-P -19.3 150.5 30 -0.73 IVA SLG 23-37-42.8 159.8 26 0.40 CRG PN -29.2 211.3 332 -0.43 TVG PN -31.4 228.1 313 -0.27 S-P -30.0 -0.36 DCT SLG 23-38-06.9 245.0 340 0.55 (NOTE: Update on GIT epicenter-LAT= 32.724N LONG= 83.459W DPTH= 3.3 KM) --Information purposes only--see TEIC listing page 33-- *TEIC LAT= 32.74N LONG= 83.20W H= 23-36-50.4 DPTH= 6.0 KM NO=6, RMS RES=0.33 SEC, GAP=347 DEG, ERH=35.4 KM, ERZ=12.3 KM, Q=D, SQD=D 11 DECEMBER 1982 MACON, GEORGIA ML= 2.0 (GIT), MLD= 2.5 (TEIC) *GIT LAT= 32.853N LONG= 83.532W H= 00-25-08.3 DPTH= 0.0 KM, FXD ERROR ELLIPSE (DERIVED FROM HYPO71): SEMI-MAJOR AXIS= 3.7 KM SEMI-MINOR AXIS= 1.4 KM AZ OF MAJOR AXIS= 95 DEG AREA OF ELLIPSE= 16 SQ KM STA PHASE TIME DIST (KM) AZ (DEG) RES (SEC) BEV PLG 00-25-34.1 156.2 28 -0.45 LDV PLG -35.6 164.1 29 -0.26 SLG -55.3 -0.34 IVA PLG -38.0 173.7 25 0.55 SLG -58.3 -0.04 TVG PLG -48.5 236.8 316 0.63 SLG -26-16.1 0.06 HGA SLG -23.6 267.0 306 -0.95 DCT PLG -25-51.6 257.9 342 0.23 SLG -26-22.5 0.52 --Information purposes only--see TEIC listing page 33-- *TEIC LAT= 32.67N LONG= 83.46W H= 00-25-05.6 DPTH= 6.0 KM NO=9, RMS RES=1.31 SEC, GAP=322 DEG, ERH=59.9 KM, ERZ=19.8 KM, Q=D, SQD=D/D 14 DECEMBER 1982 TN-NC BORDER MLD= 2.2 (TEIC), ML= 3.0 (GIT) (Approximately 17 KM N of Hiwassee, North Carolina) *TEIC LAT= 35.30N LONG= 84.16W H= 06-35-10.1 DPTH= 13.3 KM NO=29, RMS RES=0.11 SEC, GAP=100 DEG, ERH=0.2 KM, ERZ=0.3 KM, Q=B, SQD=A/B (See TEIC listing page 33.) *GIT LAT= 35.302N LONG= 84.130W H= 06-35-09.6 DPTH= 0.0 KM, FXD ERROR ELLIPSE (DERIVED FROM HYPO71): SEMI-MAJOR AXIS= 0.9 KM SEMI-MINOR AXIS= 0.8 KM AZ OF MAJOR AXIS= 131 DEG AREA OF ELLIPSE= 2 SQ KM STA PHASE TIME DIST (KM) AZ (DEG) RES (SEC) TLT PLG 06-35-13.0 14.0 270 0.72 SLG -15.0 0.30 ETT PLG -15.3 29.7 275 0.42 SLG -18.7 -0.42 DCT PLG -16.5 38.1 224 0.23 SLG -20.7 -0.77 TKL PLG -18.7 51.1 39 0.28 SLG -24.9 -0.22 BBG PLG -19.8 55.6 148 0.63 SLG -26.8 0.39 HPK PLG -22.1 72.9 18 0.08 SLG -30.6 -0.65 CRG PLG -23.8 82.3 210 0.21 SLG -33.2 -0.71 IVA PLG -38.0 170.0 132 -0.07 SLG -58.1 -0.42 15 DECEMBER 1982 LENOIR CITY, TENNESSEE MLD= 2.2 (TEIC), ML= 2.6 (GIT) *TEIC LAT= 35.75N LONG= 84.22W H= 02-27-59.3 DPTH= 16.8 KM NO=25, RMS RES=0.12 SEC, GAP=195 DEG, ERH=0.3 KM, ERZ=1.9 KM, Q=C, SQD=A/D (See TEIC listing page 33.) *GIT LAT= 35.737N LONG= 84.217W H= 02-27-59.4 DPTH= 0.0 KM, FXD ERROR ELLIPSE (DERIVED FROM HYPO71): SEMI-MAJOR AXIS= 2.7 KM SEMI-MINOR AXIS= 0.8 KM AZ OF MAJOR AXIS= 139 DEG AREA OF ELLIPSE= 1 SQ KM STA PHASE TIME DIST (KM) AZ (DEG) RES (SEC) CBT PLG 02-28-05.1 28.6 220 0.60 SLG -09.4 0.79 HPK PLG -06.0 37.1 56 0.11 SLG -10.9 -0.08 TLT PLG -08.2 48.7 187 0.39 SLG -14.4 0.16 DCT PLG -12.6 77.9 194 -0.04 SLG -22.1 -0.34 RHT PLG -15.0 94.7 220 -0.42 SLG -26.8 -0.36 TVG PLG -29.0 180.0 214 -0.51 S-P -24.2 0.25 21 DECEMBER 1982 MACON, GEORGIA ML= 2.7 (GIT) *GIT LAT= 32.799N LONG= 83.519W H= 05-30-46.2 DPTH= 0.0 KM, FXD ERROR ELLIPSE (DERIVED FROM HYPO71): SEMI-MAJOR AXIS= 2.0 KM SEMI-MINOR AXIS= 0.7 KM AZ OF MAJOR AXIS= 100 DEG AREA OF ELLIPSE= 1 SQ KM STA PHASE TIME DIST (KM) AZ (DEG) RES (SEC) CH6 PLG 05-31-12.2 152.7 37 0.36 SLG -29.8 -0.49 CH5 PLG -12.3 153.3 47 0.37 SLG -30.0 -0.46 BEV PLG -13.1 160.9 27 -0.08 SLG -32.2 -0.38 LDV PLG -14.7 168.8 27 0.21 IVA PLG -16.4 178.6 24 0.28 SLG -37.9 0.33 CRG PLG -24.0 229.0 335 -0.35 SLG -52.0 0.28 TVG PLG -27.2 241.9 317 0.62 SLG -56.0 0.65 TDA PLG -27.8 248.7 290 0.10 SLG -56.8 -0.46 HGA PLG -31.0 271.6 307 -0.49 SLG -32-03.2 -0.49 THE TWIGGS COUNTY, GEORGIA, EARTHQUAKE SWARM OF DECEMBER 1982-MARCH 1983 This swarm began early in December, 1982, in central Georgia and was ongoing as of March 1, 1983. It has consisted of some 100 events that were recorded by the Georgia Institute of Technology's (GIT) Clark Hill Network (stations: BEV, CH5, CH6, EP1, IVA, LDV and RF1) at an epicentral distance of about 150 km. Local magnitudes range from 1.5 to 3.5. The three Macon, Georgia, shocks (December 8, 11 and 21) listed in the preceding pages are part of this swarm. A GIT aftershock survey with portable seismographs showed the cited computer locations for those events (about 32.85N-83.52W) to be slightly in error and the true location to be nearer to 32.71N-83.47W. The above communications and the following preliminary listing of Twiggs County seismic events are from Anthony P. Johnson of GIT. LISTING OF TWIGGS COUNTY SEISMIC EVENTS (Preliminary Data) Date Origin Time mb(Lg)Dur* 5 Dec 1982 11:11:02.6 2.7 7 Dec 1982 00:19:25.6 2.7 05:27:03.3 2.5 8 Dec 1982 15:00:15.2 2.4 23:36:50.8 2.8 10 Dec 1982 16:48:39.3 2.4 22:17:03.8 ? 22:40:51.7 2.1 23:23:21.6 2.1 11 Dec 1982 00:12:22.4 2.5 00:25:06.7 3.0 00:39:16.4 2.4 00:44:03.4 2.1 03:47:28.1 2.6 13 Dec 1982 01:21:18.9 2.7 22:57:18.6 2.5 22:58:16.4 2.6 15 Dec 1982 17:44:36.4 2.4 19:31:52.3 2.2 17 Dec 1982 18:01:37.3 2.4 21:01:58.6 2.2 19 Dec 1982 15:37:33.4 2.4 20 Dec 1982 20:29:49.8 2.6 21 Dec 1982 01:40:02.3 2.2 04:45:44.1 2.4 05:30:45.7 2.7 06:43:51.5 2.2 07:00:07.0 2.1 07:40:14.0 2.4 08:01:59.5 2.7 10:13:08.8 2.2 17:05:55.8 2.2 22 Dec 1982 03:47:42.8 2.2 23 Dec 1982 07:52:43.1 2.4 09:56:36.0 2.4 10:57:00.0 2.1 11:52:11.3 2.6 25 Dec 1982 10:56:37.3 2.4 *From Chaplin, Taylor and Toksoz (1980), Eqke. Notes, 51, no. 4, pp. 15-22: mb(Lg)Dur = -1.7 + 2.21 log T TENNESSEE EARTHQUAKE INFORMATION CENTER LISTING OF HYPOCENTERS FOR JULY-DECEMBER, 1982 PERIOD The Tennessee Earthquake Information Center (TEIC) of Memphis State University publishes a TEIC QUARTERLY SEISMOLOGICAL BULLETIN. Those BULLETINS are similar in format to this SEUSSN BULLETIN and contain detailed network station maps, epicenter maps, arrival-time data, hypocenter listings, etc. Their Volume III, Numbers 3 and 4, covers the July-December, 1982, period of this BULLETIN. We will not duplicate the detailed listing of their arrival-times, epicentral distances and azimuths and travel-time residuals in this BULLETIN. Rather, we will provide in the following a list of their hypocentral locations and error parameters for those events occurring within the SEUSSN area. Contact TEIC Director, Dr. Arch Johnston (901-454-2007) for additional information concerning their BULLETIN. DATE ORG TIME LAT N LONG WDEPTH MAG GAP Q SQD RMS ERH ERZ ST/PH 820710 2242 27.2 35.79 82.68 11.28 1.4 216 D C/D 0.13 3.37 3.67 3:6 NW of Asheville, NC 820716 1416 1.8 34.28 81.51 5.68 3.1 295 C B/D 0.20 2.41 2.65 5:10 SC-Information purposes only 820719 0434 42.8 35.79 83.75 18.34 0.9 228 C B/D 0.03 1.18 0.82 3:5 SE of Knoxville, TN, approximately 25 km 820813 0252 58.2 34.31 81.51 10.65 1.9 294 D D/D 0.52 6.70 8.65 4:8 SC-Information purposes only 820825 0744 47.8 35.91 83.91 15.08 1.5 147 B A/C 0.11 0.44 0.28 7:14 SE Knoxville, TN 820902 2152 45.2 34.93 82.92 2.34 2.8 228 C B/D 0.24 1.33 1.68 7:11 SC/GA/NC border area 820905 1011 9.4 35.20 84.51 13.36 3.2 79 B A/B 0.13 0.41 0.48 14:21 Felt: in Etowah, TN, area 820907 0756 45.4 35.28 84.11 16.00 0.7 244 D C/D 0.12 4.1744.39 3:5 TN/NC border area 820920 1701 48.6 36.04 83.86 13.05 1.7 241 C A/D 0.12 0.83 0.46 6:12 N. Knoxville, TN 820921 0107 18.4 36.10 83.73 16.96 1.6 242 C A/D 0.13 0.58 1.21 11:20 N of Knoxville, TN, approximately 5 km 820924 2157 42.4 35.68 84.24 14.26 3.2 61 B A/B 0.15 0.41 0.56 19:25 Felt: In Knox, Loudon, Blount, Anderson and Monroe Counties, TN The maximum intensity (MMI)= IV 820924 2219 16.9 35.69 84.25 10.47 3.4 63 B A/C 0.12 0.31 0.48 18:25 Felt: In Knox, Loudon, Blount, Anderson, Monroe and McMinn Counties, TN The maximum intensity (MMI)= IV 820924 2254 11.7 35.68 84.25 6.65 N/A 167 B A/C 0.09 0.33 1.31 6:11 SW of Lenoir City, TN 821018 0426 27.0 35.68 84.24 16.00 318 C A/D 0.05 4:6 S of Lenoir City, TN, approximately 5 km 821022 0234 30.6 36.37 84.15 4.51 1.8 218 C A/D 0.11 0.7 1.6 9:12 W of Jellico, TN, approximately 2 km 821031 0307 37.5 32.49 84.95 16.00 2.9 323 D D/D 0.1618.6 23.4 10:14 Macon, GA-Information purposes only 821031 0312 12.0 32.37 84.97 16.00 3.0 324 D D/D 0.0926.9 34.4 11:15 Macon, GA-Information purposes only 821102 0844 45.8 35.75 83.96 10.76 1.3 141 B A/C 0.08 0.4 1.0 5:9 E of Marryville, TN, approximately 5 km 821108 0956 10.0 35.42 84.51 25.39 149 C C/C 0.42 3.9 4.1 6:9 SE of Athens, TN, approximately 1 km 821114 1031 58.9 36.20 82.87 12.00 2.4 118 B A/C 0.14 0.4 0.7 12:23 N of Greenville, TN, approximately 15 km 821130 1150 3.8 35.41 84.36 19.10 -0.2 174 B A/C 0.08 0.4 0.7 6:10 NW of Telico Plains, TN, approximately 10 km 821201 1339 44.6 35.26 84.43 13.15 107 B A/B 0.08 0.4 0.6 6:11 S of Etowah, TN, approximately 12 km 821206 1052 34.9 36.13 83.71 10.59 2.0 196 C B/D 0.20 1.1 1.0 8:14 E of Knoxville, TN, approximately 12 km 821208 2236 50.4 32.74 83.20 6.00 2.4 347 D D/D 0.3335.4 12.3 4:6 Macon, GA-Information purposes only 821211 0025 5.6 32.67 83.46 6.00 2.5 322 D D/D 1.3159.9 19.8 6:9 Macon, GA-Information purposes only 821214 0635 10.1 35.30 84.16 13.28 2.2 100 B A/B 0.11 0.2 0.3 17:29 N of Hiwassee, NC, approximately 17 km 821215 0227 59.3 35.75 84.22 16.80 2.2 195 C A/D 0.12 0.3 1.9 14:25 S of Lenoir City, TN, approximately 5 km U.S.G.S. SOUTH CAROLINA SEISMIC NETWORK This network experienced operational difficulties during this report period. The following is a list of possible South Carolina earthquakes detected by the network. The list has been culled of all probable blasts. All times are from visual records and thus are accurate to one-tenth of a second. SOUTH CAROLINA EARTHQUAKES JULY 1-DECEMBER 31, 1982 DATE TIME STA PHASE REMARKS 0805 0310:11.5 SBK IP These three had similar codas, lasting 20-30 seconds 0315:04.2 2030:23.2 0825 1341:30 ZIN IP Visible on SVS and OSB also, very small 0906 1237:14.5 SBK EP These three had similar codas, lasting less than 1244:01.0 10 seconds, S-P times 1-2 seconds 1254:04.5 0913 2246:12.8 PRM IP S-P time 2.4 seconds, duration 53 seconds 1010 0005:37.7 ZIN IP Both these had 10 second durations 0006:47.0 1013 0247:05.6 ZIN EP S-P time .7 second, duration 3 seconds 1120 1750:32.5 MGS IP S-P time 3.2 seconds, duration 42 seconds 1123 1027:59.0 ZIN EP Small 1223 0316:28.8 PRM IP S-P time 2.9 seconds, duration 60 seconds ACKNOWLEDGMENTS In addition to the support furnished by the host institutions of the network contributors, partial or full support by other agencies for the operation of portions of the SEUSSN is gratefully acknowledged. The agencies providing support to the members of SEUSSN are as follows: The National Science Foundation - Geophysics Program, The Nuclear Regulatory Commission - Office of Reactor Safety Research, The United States Geological Survey - Office of Earthquake Studies, The Georgia Power Company, The Virginia Electric and Power Company. ERRATA AND ADDENDA In SEUSSN BULLETIN NO. 10 an event outside of the SEUSSN area was listed. That event was at 01h-22m on 17 April 1982 and the GIT location in western Tennessee was given. The TEIC location for that event (from their Bulletin, Vol. III, No. 2) is as follows: DATE ORG TIME LAT-N LONG-W DPTH MAG 820417 01-22-54.9 35-54.53 89-03.55 5(FXD) 2.8 GAP Q SQD RMS ERH ERZ 136 C B:C 0.21 0.5 1.5 In SEUSSN BULLETIN NO. 10, two Tennessee events (15h-28m on 5 May 1982 and 21h-09m on 17 June 1982) were listed as earthquakes. The TEIC interpretation for those events is that they are probable blasts. In SEUSSN BULLETIN NO. 10, a TEIC event at Greenback, Tennessee, was listed as occurring on 29 May 1982. That date should be changed to 30 May 1982.