Book summary: In the newly revised Second Edition of the Handbook of Archaeological Sciences, a team of more than 100 researchers delivers a comprehensive and accessible overview of modern methods used in the archaeological sciences. The book covers all relevant approaches to obtaining and analyzing archaeological data, including dating methods, quaternary paleoenvironments, human bioarchaeology, biomolecular archaeology and archaeogenetics, resource exploitation, archaeological prospection, and assessing the decay and conservation of specimens [...]

Ground penetrating radar (GPR) is limited by the depth of penetration and signal-to-noise ratio (SNR), which both impact the ability to resolve subsurface features. GPR antennas are known to have limited depth penetration due to the noise and signal attenuated. The noise floor is the depth at which there is no discernable signal (Stec and Susek 2018). SNR is the comparison of desired signal to background noise, understanding that noise is any unwanted signal. Different objects in the environment can transmit frequencies that are recorded in data as background noise; this noise is considered to be external noise. Internal noise is noise which is generated by the internal components of the GPR system. Data processing such as filtering can reduce noise. Noise that occurs at the same frequency as the signal of interest, however, cannot be filtered out without also removing the signal of interest.

Thesis. 1976. Sc.D.--Massachusetts Institute of Technology. Dept. of Earth and Planetary Sciences. / Microfiche copy available in Archives and Science. / Bibliography: leaves 208-213. / Sc.D.

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Earth and Planetary Sciences, 1979. / Microfiche copy available in Archives and Science. / Bibliography: leaves 163-173. / by Kenneth Robert Anderson. / Ph.D.

Oceanic strike-slip earthquakes occur on transform faults and fracture zones that cut across thousands of kilometers of seafloor. The largest of these events often rupture a considerable portion of their associated fault and can provide a comprehensive look at seismic slip across the entire fault plane as well as constraints on the depth extent of seismic slip. It is generally accepted that seismic and aseismic slip along oceanic transform faults is thermally controlled, however composition and geometry have been proposed as significant controls on some faults. High strain rates are a mechanism to achieve greater rupture depths, such as the unusually deep centroids reported for the largest strike-slip earthquake recorded to date, the 2012 MW 8.6 Indian Ocean earthquake. Detailed studies of notable earthquakes and a scattering of well-known faults have been of great use in elucidating oceanic strike-slip rupture. Determining if observed behavior is characteristic of all oceanic strike-slip faults requires a different approach. To resolve how seismic and aseismic slip are controlled with depth and along strike, well-constrained depths of many earthquakes along oceanic strike-slip faults are determined by modeling teleseismic body waves. Finite-fault slip inversions are calculated for the largest, most recent, and best-recorded oceanic strike-slip events. The constrained depth and along-strike location of slip for numerous oceanic earthquakes on strike-slip faults illuminates the distribution of seismic rupture on these faults in detail, as well as in unprecedented breadth through the examination of oceanic faults in a range of spreading rates and lithosphere ages. These well-constrained depths are within the expected limit to brittle failure (600-800ºC) and show that seismic rupture extends throughout the upper mantle to the crust. Observations of seismic rupture along an oceanic strike-slip fault also provide a comparison to the behavior of continental strike-slip faults that pose a far greater hazard to population centers, such as the San Andreas Fault in the Western United States and the North Anatolian Fault in Turkey.

Thirty-nine construction blasts were monitored by mobile and fixed seismic arrays to develop a crustal velocity model in the Bath County, Virginia locale (June-August, 1982). The results indicate an upper-layer with P and S velocities of 5.45 km/sec and 3.07 km/sec respectively, and a thickness 3 km. Data from the 2 most distant observing stations indicate a second layer with a P velocity of 6.04 km/sec. Based on other studies in Virginia, lower crustal layers with P and S velocities 6.05 km/sec and 3.52 km/sec (11.7 km thickness) and 6.53 km/sec and 3.84 km/sec (36.0 km thickness) and upper mantle velocities of 8.18 km/sec and 4.79 km/sec are assumed. These layers make up the discrete velocity layer model. The observed travel-time data cannot be distinguished from theoretical travel-times calculated from either of two other models utilizing linear increases in velocity with depth. The first of these models uses a linear increase in P velocity from 5.45 km/sec at the surface to 6.53 km/sec at 50.7 km depth. The surface VP/VS ratio of 1. 74 is assumed for this entire layer. Beneath this layer is the mantle with P and S velocities 8.18 km/sec and 4.79 km/sec. The second of these models uses a linear increase in P velocity from 5.45 km/sec at the surface to 6.05 km/sec at 14.7 km depth. The surface VP/VS ratio is again assumed for this layer. Beneath this layer is the 36.0 km thick 6.53 km/sec layer underlain by the mantle. A test of the locational capabilities of the Bath County Network utilizing construction and quarry blasts was carried out for the 3 different velocity models. All three models gave virtually identical locations. The tests indicate an average of less than 1 km epicentral and depth errors inside the network. On the edge of the network, accuracy degrades to 3 km epicentral error with poor depth control. The Bath County area is seismically quiescent. Portable seismographs recorded over 3,000 hours of low noise seismic data in June, July and August of 1982 and failed to detect any local earthquake activity. Network monitoring by a permanent 4 station microearthquake network from November 1978 to November 1982 resulted in 11 recorded events. Three of these events were too small to be located. The other 8 events were located using all 3 velocity models. The linear increase in velocity over mantle model was eliminated from further consideration due to poor performance in event location. The other two models gave virtually identical locations. For these two models, the events form an apparent east-west trend. Reliable focal wave polarities and SV/P amplitude ratios, mechanisms, using both P indicate one nodal plane striking east-west and dipping to the south. The other nodal plane, which defines the mode of faulting, is poorly constrained. / Master of Science

Twenty-four blasts from three quarries operating in the central Virginia area were used, first to test the locational capabilities of the Central Virginia - North Anna Network and then to generate relative station delay suites for network stations. Using two different methods of approximating blast origin times, the Closest Station Method (CSM) and the Single Iteration Method (SIM), station delays were derived for different areas within central Virginia. Application of these station delay suites reduced locational errors in the general area from an average of 3.0 ± 1.2 to 1.7 ± 0.6 km (95% confidence level). In both cases, the average equivalent radii, a linear measure of error ellipse size, were 1.3 km. However, this result depends primarily on the improvement at one of the three quarries, where the locational error was reduced from 6.5 km to 2.6 km. Utilizing one of these methods (the SIM), lateral varational patterns in velocity were inferred and determined to be velocity banding similar to that observed in the Piedmont province in Georgia, North and South Carolina. / Master of Science

Following Hasegawa and Sacks (1981), the Benioff zone geometry beneath southern Peru is determined using 32 months of arrival-time data from a local seismic network. Various earthquake location algorithms a re-tested by comparing the locational estimates and error statistics produced by each, to determine if any one method produces solutions which are more stable than the others. No significant differences were found among three of the four methods considered for this data set. We then compare the epicentral and depth confidence intervals produced by these algorithms using the method described by Evernden (1969), and find that the three-parameter method produces confidence regions which are smaller and require more assumptions than the four-parameter method's. Therefore, the four-parameter method, including both P and S arrivals was used in this study. Our data set includes 2476 located events, of which 205 are chosen to be master events; earthquakes with the most reliable locations. All the events are then relocated using source- region dependent station corrections derived from the station residuals of the master events. We find that the Benioff zone in the more southerly region of our study area dips at a nearly constant 30°, while in the more northerly region this trend is apparent only down to a depth of 100 Km., at which point the Benioff zone becomes nearly horizontal. By analyzing the spatial aspects of our data set between these two regions, we infer that the deformation of the Benioff zone is continuous; i.e., there is no discontinuity in the seismicity that might suggest a tear in the subducting plate. / M.S.

Estimates of the apparent quality factors Q_Lg (attenuation determined from the spatial decay of Lg waves) and Q_c; (attenuation determined from the temporal decay of seismic coda waves) are made for the crust of Virginia and its environs. The results are presented in the form Q_(Lg,C)(f) = Q₀f^N, where Q₀ = Q_(Lg,C)(1 Hz) and N represents the frequency dependence. The study area is located in the Appalachian region of Virginia and eastern Tennessee, containing three areas of regionally high seismicity: the central Virginia, Giles County, and eastern Tennessee seismic zones. The attenuation of the Lg phase was studied using vertical component digital recordings from Virginia Tech Seismological Observatory network stations. The seismic sources were ten regional surface mine explosions and six regional earthquakes. It was determined that Q_(Lg,C) can be represented by Q₀ = 186, σ_logQ₀ = 0.05, and N = 1.1 ± 0.1 for the frequency band 1-4 Hz. A site effect corrected estimate of Q_(Lg,C) was also determined for the study area. This was accomplished using a spectral ratio method in which station site effects and instrument responses are canceled out. For the frequency band 1-10 Hz the site independent apparent quality factor can be represented by Q₀=155, σ_logQ₀ = 0.1, and N=1.2±0.2. Station site factors were estimated using a mean residual technique. The decay of seismic coda waves across the Giles County, Virginia seismic network was studied to estimate Q_c for western Virginia. A relatively new spectral method was used. The seismic sources were four local earthquakes. For the frequency band 1-10 Hz, the results can be represented by Q₀= 111, σ_logQ₀ = 0.07, and N = 1.3 ± 0.07 . These values agree with a limited number of results obtained using a bandpass, time domain method which showed Q₀ = 132, N = 1.3. The results obtained for the Virginia area differ significantly in the 1 - 3 Hz range from those reported in most previous studies of the eastern United States. Previous studies have generally shown 800 ≤ Q₀ ≤ 1000 and 0.3≤ N≤0.5, but many of those results are for much larger regions and determined using different analysis techniques. Several reasons that could account for the different results include 1) estimates of attenuation may be affected by incorrect geometrical spreading models, 2) the size of the study area may affect the estimates, and 3) estimates of Q_(Lg,C) made for broad regions may be biased by zones of differing tectonic activity. Of these factors, only the effects of changing geometrical spreading coefficients and scattering models (related to study area) can be quantified. Neither of these affect the results by more than a factor of two. The high frequency dependence values (N≃1.1) are probably influenced by the lack of definition of higher frequency (≃10 Hz) data at the path distances studied. Future studies should employ more extensive data sets covering a larger geographic area. At greater distances, the attenuation of higher frequency waves may be more easily observable. The large frequency dependence values are probably indicative of an area where scattering dominates over anelastic attenuation. The folded and thrusted Appalachian provinces may, indeed, be such a region of high scattering. Such a mechanism may also help to explain southeastern United States meizoseismal areas that are small relative to the total felt areas. Large frequency dependence results for Q_Lg and Q_c are relevant with respect to seismic hazard. We do not believe the results are overly biased by station site effects or varying source effects and if they hold for magnitudes greater than those studied here (m < 4.2) , they indicate a greater potential for damage by higher frequency waves to engineering structures in Virginia and its environs than previously assumed. / Master of Science

The National Science Foundation has announced a plan to establish a Deep Underground Science and Engineering Laboratory (DUSEL) for interdisciplinary research in physics, geosciences, biosciences and engineering. The proposed laboratory will extend to a depth of about 2200 meters and will consist of research facilities for long term study. To date, eight sites in North America have been proposed to host DUSEL. One of these sites, known as Kimballton, is located near Butt Mountain in Giles County in southwestern Virginia. Two seismic lines were acquired along the top of Butt Mountain in June of 2004 to support the ongoing integrated site characterization effort by the Kimballton Science Team. Both lines, approximately 3 km in length, are standard multifold seismic reflection data aimed at imaging faults, thrust sheets, and repeated sections of Paleozoic rocks in the vicinity of the proposed Kimballton site. Crooked line geometry, irregular geophone spacing, ground roll, and poor impedance contrasts between juxtapositioned rock units were challenges in processing the data. Non-standard processing techniques included the use of travel time tomography to accurately constrain near surface velocities, the use of 2D median filters to remove ground roll, and stacking only offsets exceeding 500 m. Interpretation of seismic data supports a triplicated stratigraphic section caused by the stacking of the the St. Clair and Narrows thrust sheets. The St. Clair and Narrows faults are interpreted as shear zones within ductile units of the Martinsburg Formation. 3D travel time tomography was used to build a near surface velocity model of Lines 1 and 2 for the purposes of imaging near surface structure and constraining the extent of topographic lineaments, which are interpreted as bedrock joint systems. Interpretation of the velocity models suggests that the broadly folded strata of the Butt Mountain synclinorium dip gently to the east along the hinge surface. The surface extrapolation of the Lookout Rock fault and the intersection of topographic lineaments with the seismic lines are expressed as low velocity zones that extend to depths of 150 m. This may be related to accelerated weathering along jointed rock surfaces. Results of this study have already been incorporated into the NSF proposal submitted by the Kimballton Science Team (http://www.phys.vt.edu/~kimballton/s2p/b2.pdf). / Master of Science