Operation Jangle - Nevada Proving Grounds October - November 1951

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The purpose of the survey was to obtain subsurface velocity variation with depth and, if possible, locate an area of sufficient size and honogeneity to be used in future operations. Faults and bedrock depth, when less than 500 feet, were to be located. Yucca Flat is an all alluvial fill in a basin-range valley typical of the area. The area is extremely dry and the surface very sandy in many places. To date no water has been found in Much of the area around the valley is covered with Tertiary volcanics, (rhyolite and tuffs) and several faults exist in the During the survey temperatures were high most of the time and there was rain and electrical disturbance. Equipment maintenance was a big problem. There was a good survey control over most of the area with benchmarks spaced about one mile apart. The average elevation of the area was about 4300 feet. A churn drill was used to drill four test holes to a depth of 500 feet and the formations drilled in them were essentially the It was hoped at the beginning that the shooting could be done without drilling, but energy return was so poor that, in many areas, drilling was necessary and was used in all work. A Republic drill was used and the drilling was difficult as most of it was in loose or very slightly cemented gravels. Recording was done with a United Geophysical Company truck using a special set of U. G. C. instruments designed especially for refraction work and the first breaks were of primary interest. Attempts to get reflections were unsatisfactory. Time lines were controlled by a tuning fork and appear every 0.010 second. Time is estimated to 0.001 second on the records. The records are labeled and time marks are numbered. No cor rection was made for elevation. Velocities shown on the cross section are refraction or hori zontal velocities. Since these are so random in many cases, it is assumed that they come from discontinous beds and do not necessarily represent the velocity for an interval as shown on the section. If & low-velocity layer occurs below a high-velocity layer, it will not appear on the travel-time curve. The vertical velocities from the churn drill holes were thought to give a much better velocity varia tion with depth than the refraction curves.

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The purpose of the surrey was to obtain subsurface velocity variation with depth and, if possible, locate an area of sufficient size and honogeneity to be used in future operations. Faults and bedrock depth, when less than 500 feet, were to be located. Yucca Flat is an all alluvial fill in a basin-range valley typical of the area. The area is extremely dry and the surface very sandy in many places. To date no water has been found in Much of the area around the valley is covered with Tertiary volcanics, (rhyolite and tuffs) and several faults exist in the During the survey temperatures were high most of the time and there was rain and electrical disturbance. Equipment maintenance was a big problem. There was a good survey control over most of the area with benchmarks spaced about one mile apart. The average elevation of the area was about 4300 feet. A churn drill was used to drill four test holes to a depth of 500 feet and the formations drilled in them were essentially the It was hoped at the beginning that the shooting could be done without drilling, but energy return was so poor that, in many areas, drilling was necessary and was used in all work. A Republic drill was used and the drilling was difficult as most of it was in loose or very slightly cemented gravels. Recording was done with a United Geophysical Company truck using a special set of U. G. C. instruments designed especially for refraction work and the first breaks were of primary interest. Attempts to get reflections were unsatisfactory. Time lines were controlled by a tuning fork and appear every 0.010 second. Time is estimated to 0.001 second on the records. The records are labeled and time marks are numbered. No cor rection was made for elevatjion. Velocities shown on the cross section are refraction or hori zontal velocities. Since these are so random in many cases, it is assumed that they come from discontinous beds and do not necessarily represent the velocity for an interval as shown on the section. If a low^velocity layer occurs below a high-velocity layer, it will not appear on the travel-time curve. The vertical velocities from the churn drill holes were thought to give a much better velocity varia tion with depth than the refraction curves.

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Table A.2 Lrille^s Log - Lrill Hole Ho. 1...................................................... 9 Table A.4 Lriller's Log - Lrill Hole Ho. 3.................................................... 10 Table A.S Vertical Velocity Time - Depth Tables, Drill Hole Table A.7 Vertical Velocity Time - Depth Tables, Drill Hole Table A.9 Vertical Velocity Time - Depth Tables, Drill Hole

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Figure A.2 Vertical Velocity for Drill Hole No. 1 (Geophnnes No. 1 and No. 12 at 82.5 Feet From Top of Hole) '....................................................................................15 Figure A.2 Vertical Velocity for Drill Hole No. 1 (Geophnnea No. 2 and No. 11)........................................................... 16 Figure A.4 Vertical Velocity for Drill Hole No. 1 (Geophonea No. 2 and No. 10 at 52.5 Feet From Top of Hole) .....................................................................................17 Figure A.5 Vertical Velocity for Drill Hole No. 1 (Geophonea No. 4 and No. 9 at 27.5 Feet From Top of Hole)..................................................................................18 Figure A.6 Vertical Velocity for Drill Hole No. 1 (Geophonea No. 5 and No. 8 at 22.5 Feet From Top of Hole)......................................... 19 Figure A.7 Vertical Velocity for Drill Hole No. 1 (Average of Geophonea No. 2, 4( 5, 8, 9 Figure A.8 Vertical Velocity for Drill Hole No. 2 Figure A.9 Vertical Velocity for Drill Hole No. 2 Figure A.1C Vertical Velocity for Drill Hole No. 4 A 2 / 90, A 1 ^ 45, Vith Spread From A 4 / 67.5 to A 6 / 22.5) for Drill Hole No. 1 . . . 24 A 8 / 10, A 9 / 75 Vith Spread From A 4 / 67.5 to A 6 / 22.5 for Drill Hole

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▲ 127 f 32.5 to 125 / 67.5) for Drill 127 / 32.5 to 125 f 67.5) for Drill 0 209 / 10, 0 210 -/ 75 for Circled Points Points in Squares Vith Spread From 0 205 / 67.5 to 0 207 / 32.5) for Drill Hole No. 3 ... 28 Figure 1*17 Overall Frequency Response (Per Unit Oround Particle Velocity) of Seismometer, implifier and Galvanometer........................................................... 30 Figure 1.18 Average Velocity as a Function of Depth (Average of Drill Holes No. 1, 3 and 4) ......................... 31 Figure A. 19 Seismic Refraction Survey vith Isopach, Surface to Bedrock, Ifye County, Nevada............................. 33

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SECTION 1 THE SITE................................................................................................... 1 1*2 Operation Conditions atthe Site................................ 1 SECTION 2 SEISMIC REFRACTION DETERMINATIONS ..................................... 2 SECTION 3 DETAILS OF OPERATIONS.................................................................. 4 3.3 Shot Hole Drilling............................................................... 5 APPENDIX A TABLES AND IIIDSTRATIONS........................................................ 8

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The United Geoph/eical Company, Inc., conducted a seismic refrac tion survey on the Atomic Energy Commission Test Site in Ifye County, Nevada. The survey was carried out under Navy Contract Hoy 26616, negotiated with the Public Works Office, 11th Naval District, San jDiego, California. It commenced on May 25 and ended on July 27, 1951. trict. The field work was carried out under the direction of Captain was Party Chief of Party No. 20, United Geophysical Company. BEST AVAILABLE COPY fa fafa fafa I fa fa fa fa fa fa fa fa (a

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Bsproduced Direct from Manuscript Copy by ABC Technical Information Service Oak Ridge, Tennessee

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This document consists of 51 Ho. •- (3of 295 copies. Series A SEISMIC REFRACTION SURVEY FOR NYE COUNTY, NEVADA UNITED GEOPHYSICAL COMPANY. INC. PASADENA TULSA HOUSTON NEW YOPK CAL9AAV FAIPSANKS CAHACAS RIO DE JANEIRO SANTIAGO

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This document contains»y£«fmation affecting the national defense o^VyyUnited States within the meaning of the^^Sfcnage Laws, Title 18 sion or the rsj^&pron of its contents in any manner to an unavmorized person is prohibited

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The area surveyed. Yucca Elat, was all alluvial fill In a haslnrange valley typical of the area. The surface was very sandy In many places and two-wheel drive vehicles had considerable difficulty work ing off the road. The area Is extremely dry. A few Joshua trees along the south edge of the valley are the only trees except for the plateau on the west. There are a few springs with a very small discharge along the west side of the valley. To date no water has been found In Yucca Elat, although one hole was drilled to a depth of over 1500 feet show ing a slight trace of water at the bottom. There are some good wells In Frenchman Elat which Is the next valley to the south of Yucca Elat. Much of the area around the valley Is covered with Tertiary vol canics, (rhyolite and tuffs). One hill of limestone outcrops on the east side of the valley. There Is a granite outcrop at the north end of the valley with some mineralization. Several faults exist In the vicinity, one of which can be observed In the valley hy a well de Temperatures were high most of the time. There was considerable rain and electrical disturbance the last two weeks of the project. 1.2 OPERATING CONDITIONS AT THE SITE The road was under construction during the survey. At the begin ning of the survey, approximately 25 miles of the road was hard sur faced and the remainder was a poor, oneway gravel road. About 10 days before the survey was finished, the road had been built Into the area and all but about 10, miles had been hard surfaced. Doe to poor road conditions. It required about five hours driving time per day to and from the field at the start of the prospect. The crew lived at Indian Springs Auxiliary Air Force Base except for the last two weeks of the job when they moved to a new camp about five miles from the area. Indian Springs Is about 60 miles from the area surveyed. Equipment maintenance was a big problem. Any major breakdown requiring garage work meant a 100 mile trip to the nearest garage. Routine greasing and maintenance was done In the field by the crew.

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SEISMIC REFBACTION DETERMINATIONS The purpose of the survey was to obtain subsurface velocity variation with depth and, if possible, locate an area of sufficient size and homogeneity to be used in future operations. Faults and bedrock depth, when less than 500 feet, were to be located. The field procedure was to shoot at the end of an 1100 foot spread and then at 1100 foot intervals out to 2200 to 3300 feet from the nearest geophone. This was done at each end of every spread. Figure A.19 is a map which shows benchmarks, shotpoihts and drill holes along with an isopach of bedrock where it is less than 800 feet deep. An isopach of other velocity layers would be diffi cult to make and would probably be of little value due to the lateral variation of velocity over the area. Croes sections along each line are submitted showing travel-time curves and the Inferred subsurface section. Most of the curves have definite breaks indicating rapid velocity changes with depth. A few curves are smooth indicating a gradual increase of velocity with depth rather than breaks in velocity with depth. The vertical velocity tests indicate a velocity of approximately 3000 feet per second from the surface to a depth of 100 feet, 4000 to 4500 feet per second from 100 feet to 350 feet and 5000 to 5500 feet per second from 350 to 500 feet. Befraction velocities seem to vary over a considerable range laterally as well as vertically. In very few places does it seem that any one layer was followed by refraction waves. This can, no doubt, be expected in a deposit of this type with layers of caliche and variations in cementation. The refraction velocities which are essentially horizontal vel ocities differ from the vertical1 velocities. This is to be expected and may be explained by higher-velocity layers of limited thickness carrying refracted energy with interbedded lower-velocity material between. In this way a break in the travel-time curve would occur only when a higher-velocity layer was below and at the proper depth to appear on the records. It is believed that the vertical-velocity determinations give a better overall velocity picture than the refrac tion velocities which, in many cases, indicate velocities only in

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A fault striking north-south, crosses the nAH line at 85 + 00. The area to the west of the fault was much harder to drill and the velo cities were much higher near the surface. The drill was still in was so much different than the area to the east of the fault, it was decided hy the field operations directors to move the line to the "G" line location. Vork was started on the north end of this line and then moved to the center of the line near J}.H. #3. A hurled hedrock high was indicated Just to the north of D.H. #3. This high falls on an extension of the limestone outcrop on the east side of the valley and is assumed to he the same ridge. This caused a shift to the south and final location of zero points #1 and HQ were made hy the field directors. The remainder of the work was carried out in this region. Bedrock penetration is observed in many areas, especially along HGtt line. The hedrock velocity is about 15,000 feet per second. Since the only interest in hedrock was to he sure it was deep enough, no continued attempt was made to reach it further out in the valley. An area between G 288+ 50 and G 357 + 25 indicates several near surface layers of caliche or other cemented material in the upper 100 feet of alluvium having the same velocity. These layers may pinch out or change causing the travel path to shift from one to another and causing breaks in the travel-time curves as shown. The area being used is generally homogeneous. Much of the later al variation in velocity with depth is probably due to changes in cementation or variation in the deposit itself. Since the chumdrill holes indicated little change in formation, the change in cem entation is probably the most important factor In velocity variation.

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DETAILS OJ OPERATIONS There was very good surrey control over most of the area with 'benchmarks spaced about one mile apart. Geophone positions and shotpolnt locations were determined hy Elevations were run using a transit and stadia which was suffi ciently accurate for the type of work done. The surveyor tied Into all benchmarks close to lines laid out. Holmes and Narver Engineers spotted the starting location and bearing of the "A" line. All …