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We studied seismic‐wave generation from five small (60–122 kg) fully contained explosions detonated in Barre Granite as a part of the New England Damage Experiment (NEDE). The explosions were conducted using three types of explosives with different velocities of detonation (VOD): black powder, ammonium nitrate fuel oil (ANFO) emulsion, and composition B (COMP‐B). Empirical evidence suggests that the low VOD explosives produce more shear‐wave energy than high VOD explosives. The proposed mechanisms to explain this effect include: (a) inhibition of gas‐driven fracture propagation by thicker pulverized zone for high VOD explosions, and (b) fracture toughness increase at higher loading rate. The main objective of the experiment was to study differences in shear‐wave generation between different types of explosives, and to determine the likely mechanism responsible for these differences. Seismic amplitude analysis revealed that COMP‐B releases more energy and larger amplitude P waves for the same weight of explosives, while producing smaller amplitude S waves. Furthermore, large radial cracks were observed on the surface after the ANFO and black powder shots, while there was no surface fracturing after the COMP‐B shots. Thus, longer fractures correlate with higher S ‐wave amplitudes. However, drilling into the source region indicates that high VOD explosions may actually produce a smaller pulverized zone, which means that fracture inhibition is a less plausible explanation. Therefore we hypothesize that increase in loading rate, in combination with shorter impulse duration for high VOD explosives, inhibits fracture processes, and subsequently reduced S ‐wave radiation.

Nuclear monitoring agencies often use seismic amplitudes to estimate the yields of underground nuclear tests. Any emplacement phenomena that can alter those amplitudes and lead to bias in estimated yields must be considered in the analysis. One condition that might cause such a bias is detonation in frozen rock. Laboratory analyses (Mellor, 1971; Miller and Florence, 1991) have shown that frozen rock has faster seismic velocity and greater compressive strength than unfrozen rock. This increased strength is hypothesized to reduce the seismically estimated yield of an explosion in frozen rock. To test this hypothesis, we conducted the Frozen Rock Experiment (FRE), a series of explosions in frozen and unfrozen rock, in central Alaska during August 2006. Over 120 seismic instruments were deployed to record six detonations—three in frozen and three in unfrozen-dry media—at a wide range of distances and azimuths. The data acquired show that the frozen test site explosions had significantly larger amplitudes for all phases ( P , S , and surface waves) above 8–10 Hz. These data confirm that the frozen rock medium was stronger and resulted in a smaller seismic source radius for the explosions, thus increasing the corner frequency when compared to the unfrozen rock explosions. Between 3 and 9 Hz, the unfrozen shots produced slightly larger S and surface waves resulting in different P / S spectral ratio plots for the frozen and unfrozen shots, possibly affecting regional phase discrimination. We show that the observed amplitude differences for these shots can be effectively modeled using the Mueller-Murphy (1971) explosion source and the in situ P - and S -wave velocities for the two test sites. Differences in the velocities at the frozen and unfrozen rock test sites are caused by minor metamorphic facies changes, saturated versus dry conditions, and the presence of ice in the pores and fractures at the frozen test site. Extrapolation of the results of this study to synthetic nuclear explosions suggests there may not be significant coupling differences between explosions in frozen and unfrozen hard rock.

We present a 3D Earth Model of the Arabian Plate and demonstrate its use for the rapid assessment of play potential, with an example from the Khuff gas play in eastern Arabia. The model encompasses all strata from basement to surface, and covers an area of c. 1,200 by 1,200km with a grid size of 10km. Based on our robust sequence stratigraphic framework and a database of publically available information, the model is divided into 82 layers corresponding to key 1st, 2nd and 3rd order depositional sequences. Applied to the Khuff gas play, this enables us to rapidly produce (and update with new data if needed) a regional play risk map for the Khuff and identify areas of higher potential for this play.

Weston Geophysical Corporation (WGC) and New England Research, Inc. (NER) conducted the New England Damage Experiment (NEDE) in July 2008. The experiment included the detonation of chemical explosions in relatively unfractured, homogeneous Barre granite in Vermont, USA. Barre granite has been a worldwide standard for homogeneous, low fracture-density granite in commercial, monument, and industrial settings. The emplacement granite was characterized before and after the experiment using borehole cores and acoustic imaging. The explosions were designed with variable velocities of detonations (VOD) to fracture the rock differently. Our hypothesis was that different damage would lead to possible variations in S wave generation. During the past year, we have quantified the damage from the explosions on micro, meso, and macro scales and examined the seismic wave generation and propagation at near-source, local, and regional distances.

Regional play evaluation demands the integration of large volumes of data and information from a wide variety of sources, including wells, seismic, facies maps, structure maps and the results of basin modelling. Historically a task for an experienced explorer and a light table, the advent of geographical information systems (GIS) allows greater efficiencies and some automation of workflows, but still does not offer complete integration of data, applications and products. Furthermore, these data must lie in their wider geographical and stratigraphic context, thus requiring a regional Earth Model. We present here a 3D Shared Earth Model of the Arabian Plate in Petrel 2011*, and demonstrate its use for regional play evaluation. With an example from the Khuff gas play of eastern Arabia, we show how modern 3D workflows offer advantages to previous GIS-based techniques, and emphasize the greater efficiencies which can be realised through strong integration of all data and their interpretations within the final assessment. *A mark of Schlumberger

A series of constant strain rate, unconfined compression experiments was performed on saturated welded tuff specimens collected from Busted Butte near Yucca Mountain, Nevada. Twenty specimens were loaded to failure at strain rates ranging from 10{sup {minus}9}s{sup {minus}1} to 10{sup {minus}3}s{sup {minus}1}, under ambient pressure and temperature conditions. The strength of the specimens showed a continuous decrease with decreasing strain rate between 10{sup {minus}9} s{sup {minus}1} and 10{sup {minus}5} s{sup {minus}1}. At the highest strain rate, 10{sup {minus}3} s{sup {minus}1}, strengths were less than those observed at 10{sup {minus}5} s{sup {minus}1}, likely due to hydrofracturing within the specimen at rapid loading rates. Reduction in strength, corresponding to the decrease in strain rate, is explained in terms of stress corrosion cracking. A detailed examination of six specimens tested at a strain rate of 10{sup {minus}9} s{sup {minus}1}, using acoustic wave velocities and CT scans, shows a correlation between the nature of the microstructure of the specimens and the observed strengths and elastic moduli.

Experimental results are presented for bulk and mechanical properties measurements on specimens of the Paintbrush tuff recovered from the USW NRG-6 and USW NRG-7/7A borehole at Yucca Mountain, Nevada. Measurements have been performed on five thermal/mechanical units: TCw, PTn, TSw2, and TSw3. The following bulk properties are reported for each specimen: dry bulk density, saturated bulk density, average grain density and porosity. Confined compression to failure tests were performed on selected specimens recovered from the boreholes at confining pressures of 5 and 10 MPa. In addition, compressional and shear wave velocities were measured on the specimens prior to testing. Measurements were conducted under drained conditions at room temperature on nominally water saturated specimens. The nominal strain rate for the experiments was 10{sup -5} s{sup -1}.

Experimental results are presented for seven creep experiments on welded specimens of the Paintbrush tuff recovered from borehole USW NRG-7/7A at Yucca Mountain, Nevada. The measurements were performed at differential stresses of 40, 70, 100, and 130 MPa. The confining pressure and temperature for each of the experiments was 10 MPa and 225 {degrees}C respectively. All of the specimens were tested drained, in a room dry condition. All of the experiments were terminated prior to failure. The duration of the experiments range from 2.6 x 10{sup 6} seconds to 5.9 x 10{sup 6} seconds. Creep strain is observed for those specimens tested at a stress difference. The strain rate is not constant. A primary creep stage is observed. Secondary creep does not exhibit a constant strain rate, but decreases with increasing time.

An integral part of the licensing procedure for the potential nuclear waste repository at Yucca Mountain, Nevada, involves characterization of the in situ rheology for the design and construction of the facility and the emplacement of canisters containing radioactive waste. The data used to model the thermal and mechanical behavior of the repository and surrounding lithologies include dry and saturated bulk densities, average grain density, porosity, compressional and shear wave velocities, elastic moduli, and compressional and tensional fracture strengths. In this study, a suite of experiments was performed on cores recovered from boreholes UE25 NRG-2, 2A, 2B, and 3 drilled in support of the Exploratory Studies Facility (ESF) at Yucca Mountain. The holes penetrated the Timber Mountain tuff and two thermal/mechanical units of the Paintbrush tuff. The thermal/mechanical stratigraphy was defined by Ortiz to group rock horizons of similar properties for the purpose of simplifying modeling efforts. The relationship between the geologic stratigraphy and the thermal/mechanical stratigraphy for each borehole is presented. The tuff samples in this study have a wide range of welding characteristics (usually reflected in sample porosity), and a smaller range of mineralogy and petrology characteristics. Generally, the samples are silicic, ash-fall tuffs that exhibit large variability in their elastic and strength properties.

A laboratory investigation has been carried out to determine the effects of elevated temperature and stress on the creep deformation of welded tuffs recovered from Busted Butte in the vicinity of Yucca Mountain, Nevada. Water saturated specimens of tuff from thermal/mechanical unit TSw2 were tested in creep at a confining pressure of 5.0 MPa, a pore pressure of 4.5 MPa, and temperatures of 25 and 250 C. At each stress level the load was held constant for a minimum of 2.5 {times} 10{sup 5} seconds and for as long as 1.8 {times} 10{sup 6} seconds. One specimen was tested at a single stress of 80 MPa and a temperature of 250 C. The sample failed after a short time. Subsequent experiments were initiated with an initial differential stress of 50 or 60 MPa; the stress was then increased in 10 MPa increments until failure. The data showed that creep deformation occurred in the form of time-dependent axial and radial strains, particularly beyond 90% of the unconfined, quasi-static fracture strength. There was little dilatancy associated with the deformation of the welded tuff at stresses below 90% of the fracture strength. Insufficient data have been collected in this preliminary study to determine the relationship between temperature, stress, creep deformation to failure, and total failure time at a fixed creep stress.

An integral part of the licensing procedure for the potential nuclear waste repository at Yucca Mountain, Nevada, involves prediction of the in situ rheology for the design and construction of the facility and the emplacement of canisters containing radioactive waste. The data used to model the thermal and mechanical behavior of the repository and surrounding lithologies include dry and saturated bulk densities, average grain density, porosity, compressional and shear wave velocities, elastic moduli, and compressional and tensional fracture strengths. In this study, a suite of experiments was performed on cores recovered from the USW NRG-717A borehole drilled in support of the Exploratory Studies Facility (ESF) at Yucca Mountain. USW NRG-7/7A was drilled to a depth of 1,513.4 feet through five thermal/mechanical units of Paintbrush tuff and terminating in the tuffaceous beds of the Calico IEUS. The thermal/mechanical stratigraphy was defined by Orfiz et al. to group rock horizons of similar properties for the purpose of simplifying modeling efforts. The relationship between the geologic stratigraphy and the thermal/mechanical stratigraphy is presented. The tuff samples in this study have a wide range of welding characteristics, and a smaller range of mineralogy and petrology characteristics. Generally, the samples are silicic, ash-fall tuffs that exhibit large variability in their elastic and strength properties.

Lateral and vertical variabilities in the bulk and mechanical properties of silicic volcanic tuff at the potential nuclear waste repository site in Yucca Mountain, NV have been evaluated. Laboratory measurements have been performed on tuff specimens recovered from boreholes located to support the design of the Exploratory Studies Facility/North Ramp. The data include dry and saturated bulk densities, average grain density, porosity, compressional and shear wave velocities, elastic moduli, and compressional and tensional fracture strengths. Data from eight boreholes aligned in a northwest-southeast direction have been collected under the required quality assurance program. Three boreholes have penetrated the potential repository horizon. The information collected provides for an accurate appraisal of the variability of rock properties in the vicinity of the boreholes. As expected, there is substantial variability in the bulk and mechanical properties of the tuff with depth (lithology). This is due to variations in gross characteristics of the tuffs (e.g., cooling units, mode of deposition, etc.), as well as smaller scale features (welding, porosity, and internal structures) that have developed as a result of depositional and post-depositional mechanisms. An evaluation of the lateral variability in bulk and mechanical properties is somewhat limited, at this time, due to a lack of borehole control to the north and south (parallel to the depositional flow direction). Initial observations indicate that there is minimal lateral variability within lithologic units. There are observable differences however, that can be related to variability in specific properties (e.g., porosity, and internal structures).

Experimental results are presented for bulk and mechanical properties measurements on specimens of the Paintbrush tuff recovered from borehole USW NRG-6 at Yucca Mountain, Nevada. Measurements have been performed on four thermal/mechanical units, TCw, PTn, TSw1 and TSw2. On each specimen the following bulk properties have been reported: dry bulk density, saturated bulk density, average grain density, and porosity. Unconfined compression to failure, confined compression to failure, and indirect tensile strength tests were performed on selected specimens recovered from the borehole. In addition, compressional and shear wave velocities were measured on specimens designated for unconfined compression and confined compression experiments. Measurements were conducted at room temperature on nominally water saturated specimens; however, some specimens of PTn were tested in a room dry condition. The nominal strain rate for the fracture experiments was 10{sup -5} s {sup -1}.

Laboratory experiments were performed to measure the effect of frequency, water-saturation, and strain amplitude on Young`s modulus and seismic wave attenuation on rock cores recovered on or near the site of a potential nuclear waste repository at Yucca Mountain, Nevada. The purpose of this investigation is to perform the measurements using four techniques: cyclic loading, waveform inversion, resonant bar, and ultrasonic velocity. The measurements ranged in frequency between 10{sup {minus}2} and 10{sup 6} Hz. For the dry specimens Young`s modulus and attenuation were independent of frequency; that is, all four techniques yielded nearly the same values for modulus and attenuation. For saturated specimens, a frequency dependence for both Young`s modulus and attenuation was observed. In general, saturation reduced Young`s modulus and increased seismic wave attenuation. The effect of strain amplitude on Young`s modulus and attenuation was measured using the cyclic loading technique at a frequency of 10{sup {minus}1} Hz. The effect of strain amplitude in all cases was small. For some rocks, such as the potential repository horizon of the Topopah Spring Member tuff (TSw2), the effect of strain amplitude on both attenuation and modulus was minimal.

An integral part of the licensing procedure for the potential nuclear waste repository at Yucca Mountain, Nevada involves accurate prediction of the in situ rheology for design and construction of the facility and emplacement of the canisters containing radioactive waste. The data required as input to successful thermal and mechanical models of the behavior of the repository and surrounding lithologies include bulk density, grain density, porosity, compressional and shear wave velocities, elastic moduli, and compressional and tensile strengths. In this study a suite of experiments was performed on cores recovered from the USW-NRG-6 borehole drilled to support the Exploratory Studies Facility (ESF) at Yucca Mountain. USW-NRG-6 was drilled to a depth of 1100 feet through four thermal/mechanical units of Paintbrush tuff. A large data set has been collected on specimens recovered from borehole USW-NRG-6. Analysis of the results of these experiments showed that there is a correlation between fracture strength, Young`s modulus, compressional wave velocity and porosity. Additional scaling laws relating; static Young`s modulus and compressional wave velocity; and fracture strength and compressional wave velocity are promising. Since there are no other distinct differences in material properties, the scatter that is present at each fixed porosity suggests that the differences in the observed property can be related to the pore structure of the specimen. Image analysis of CT scans performed on each test specimen are currently underway to seek additional empirical relations to aid in refining the correlations between static and dynamic properties of tuff.

Samples of tuffaceous rock were studied as part of the site characterization for a potential nuclear waste repository at Yucca Mountain in southern Nevada. These efforts were scoping in nature, and their results, along with those of other investigations, are being used to develop suitable procedures for determining bulk properties of tuffaceous rock in support of thermal and mechanical properties evaluations. Comparisons were made between various sample preparation, handling, and measurement techniques for both zeolitized and nonzeolitized tuff in order to assess their effects on bulk property determinations. Laboratory tests included extensive drying regimes to evaluate dehydration behavior, the acquisition of data derived from both gas and water pycnometers to compare their suitability in determining grain densities, a comparison of particle size effects, and a set of experiments to evaluate whole core saturation methods. The results affirm the added complexity of these types of measurements where there is a zeolite component in the sample mineralogy. Absolute values for the bulk properties of zeolitized tuff are immeasurable due to the complex nature of their dehydration behavior. However, the results of the techniques that were investigated provide a basis for the development of preferred, consistent methods for determining the grain density, dry and saturated bulk densities, and porosity of tuffaceous rock, including zeolitic tuff in support of thermal and mechanical properties evaluations.

Experiment results are presented for unconfined compressive strength and elastic moduli of tuffaceous rocks from Busted Butte near Yucca Mountain, Nevada. The data have been compiled for the Yucca Mountain Site Characterization Project Site and Engineering Properties Data Base. Experiments were conducted on water-saturated specimens of the potential nuclear waste repository horizon Topopah Spring Member tuff (thermal/mechanical unit TSw2). The influence of strain rate on mechanical properties of the tuff was examined by loading six specimens in uniaxial compression at a strain rate of 10{sup {minus}9} s{sup {minus}1}. The experiments performed under ambient pressure and temperature conditions and conformed to Technical Procedure 91, titled ``Unconfined Compression Experiments at 22{degrees}C and a Strain Rate of 10{sup {minus}9} s{sup {minus}1}.`` The mean and standard deviation values of ultimate strength, Young`s modulus and Poisson`s ratio determined from these experiments are 85.4{plus_minus}21.7 MPa, 33.9{plus_minus}4.6 GPa, and 0.09{plus_minus}0.07, respectively.

Mechanical properties of the tuffaceous rocks within Yucca Mountain are needed for near and far-field modeling of the potential nuclear waste repository. If the mechanical properties are significantly anisotropic (i.e., direction-dependent), a more complex model is required. Relevant data from tuffs tested in earlier studies indicate that elastic and strength properties are anisotropic. This scoping study confirms the elastic anisotropy and concludes some tuffs are transversely isotropic. An approach for sampling and testing the rock to determine the magnitude of the anisotropy is proposed.

The effects of loading frequency, strain amplitude, and saturation on elastic moduli and attenuation have been measured in samples of the Topopah Spring Member welded tuff. Four different laboratory techniques have been used to determine Young`s modulus and extensional wave attenuation at frequencies ranging from 10{sup {minus}2} to 10{sup 6} Hz. The results are compared with data acquired for Sierra White granite under the same conditions. The modulus and attenuation in room dry samples remain relatively constant over frequency. Frequency dependent attenuation and modulus dispersion are observed in the saturated samples and are attributed to fluid flow and sample size. The properties of tuff were independent of strain amplitude in room dry and saturated conditions.

Sixteen creep experiments were performed on welded tuff specimens from the vicinity of Yucca Mountain, NV. The tests were performed under two conditions. One suite of measurements was performed on nominally dry specimens at a confining pressure of 10 MPa, a temperature of 225°C, and differential stresses between 40 and 130 MPa. The second suite of experiments was conducted on water saturated specimens at a confining pressure of 5.0 MPa, a pore pressure of 1.0 MPa, and a temperature of 150°C over a range of differential stresses from 115 to 150 MPa. Six of the specimens tested at 150°C failed in shear. The remaining experiments were terminated after 10 6 seconds prior to failure. All of the specimens tested showed primary and secondary stages of creep. The secondary creep strain increased as the differential stress was increased. The specimens that failed exhibited a tertiary creep stage. The specimens brought to failure were analyzed in terms of static fatigue. Based on limited data, the time to failure, 〈t〉, is given by an expression of the form 〈t〉=10 41 e-0.646 σ where σ is the differential stress applied to the specimen.

Changes in the local geomagnetic field have been observed and documented in several seismically active areas prior to, during, and following earthquakes. Mizutani and Ishido (1975) proposed that groundwater may diffuse through a hypocentral region and that the fluid flow can produce an electric potential by means of electrokinetic phenomena. The resulting current flow, in turn, will generate a magnetic field. Fluid flow tests conducted on samples of Westerly granite demonstrated that the diffusion of an electrolytic fluid causes a measurable magnetic field change. At high fluid flow rates, a magnetic field change was observed that was in agreement with theoretically predicted and numerically calculated values. In addition, the sign of the magnetic field changes as the fluid flow direction through the sample was reversed. Moreover, the tests showed that the magnitude of the magnetic field change is dependent upon (1) the porosity of the rock; (2) the pore wall surface area; (3) the permeability of the rock; and (4) zeta potential of the fluid-pore wall system.

A variety of crystalline silicate rocks of low porosity (0·001-0·03) were fractured in triaxial experiments at strain rates from about 10−3 to 10−1 sec−1. Comparison of the fracture strengths at different pore pressures provided a test of the law of effective stress for these brittle rocks. The tests revealed that the law of effective stress held for these rocks only when loading rate was less than some critical value which depended on permeability of the rock, viscosity of the pore fluid and sample geometry. In our experiments with water, it was about 10−7 sec−1 for cylindrical samples of granite several centimeters long for example. In experiments at loading rates greater than the critical value, the rock was as much as 50 per cent stronger than at zero pore pressure. Although this effect will probably have little geological application, it could well be significant for rock stressed as a result of earthquake motion or for rock in the vicinity of buried nuclear explosions.

Holographic interferometry is used to observe the strain field and the development of an intensive deformation zone in Westerly Granite specimens under loading. Copper-jacketed samples were subjected to differential stress under confining pressure up to 0.8 kbar. An elliptical bulging of the sample was observed to form at the onset of dilatancy. The ultimate failure plane and the major axis of the intense deformation zone are coincident. A bulge outlining the incipient failure plane becomes apparent below 90% of ultimate strength of the rock. In the post-failure regime, strain concentrations prior to frictional sliding of the sample are largely confined to this zone. The anelastic bulge in the intense deformation zone amounts to about twice that outside the zone at the ultimate failure of the sample.