Hello Bob
Here is the data I keep losing in computer crashed.
The first half deals with information I have culled on the use of radar (ground penetrating and side looking) in identifying geological formations.
The second half are addresses well worth surfing for up to date geological information on the history of North America. Actually the first address is all you will need as it is a slide show. The others are high lights of what I thought were some of the more relevant slides. I lost a few on another crash but it doesn't really matter.
Enjoy the read.
I still have not located that ground penetrating radar image of the Arkansas kimberlite but I will keep trying. Have a good weekend.
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IPL@UBC Research Contributions: Papers In Press 1998
JOURNAL PAPERS:
Kopylova, M. Russell. J.K. & Cookenboo, H. (In Press: 01/98) [Data]
Upper-mantle stratigraphy of the Slave Craton, Canada: Insights into a new kimberlite province. Geology.
Russell. J.K. & Stasiuk, M.V. (Accepted: 02/98) pubs-4.html
Ground-penetrating radar mapping of volcanic deposits and the Late Bronze Age paleotopography, Thera, Greece. Geological Society London, Special Volume, Volcanoes, Earthquakes & Archeology.
GOVERNMENT PUBLICATIONS:
Duncan, R.A., Russell, J.K., Hastings,N.L. and Anderson, R.G. (1998)
Geology, mineralogy, geochemistry and physical properties of the mid-Cretaceous Emerald Lake pluton, southeastern Yukon; Geological Survey of Canada, Open File 3571.
Russell, J.K. and others (1998)
The ice cap of Hoodoo Mountain: Radar estimates of shape and thickness; in Current Research 1998-, Geological Survey of Canada
Back to Index
Honours Science and Engineering Bachelors Theses
1997-1998
 Byron Nodwell [B.Sc. Honours Geology]
Title: Detection of lava tubes with ground-penetrating radar.
 Maureen Crawford [B.Sc. Honours Geology]
Title: Mineralogical & petrographic analysis of pottery sherds
from Stymphalos, Greece: Identifying composition and provenance.
1996-1997
 Wendi Milner [B.A. Sc. Geophysics]
Title: Ground-penetrating radar responses of modern volcanic deposits.
1995-1996
 Kirstie Simpson [B.Sc. Honours Geology]
Title: The geology, geochemistry and geomorphology of Mathews Tuya: A subglacial volcano in northwestern British Columbia.
1994-1995
 Darwin Green [B.Sc. Honours Geology]
Title: Characterization of the Portland Canal Dyke Swarm, Stewart Area, NW British Columbia: Including Geochronology and thermal Regime.
1993-1994
 Tony Dubin [B.Sc. Honours Physics]
Title: Non-Arrhenian Models for Silicate Melt Viscosity.
 Bill Dynes [B.Sc. Honours Geology]
Title: A Preliminary Petrologic & Geothermometric Investigation of the Mantle Xenoliths entrained within the Ranch LAke Kimberlite, NWT, Canada.
 Jason Luty [B.A.Sc. Geological Engineering]
Title:Eruption Characteristics and Industrial Application Potential of the Bridge River Airfall Pumice Deposit, Mount Meager, Southwestern, B.C.
JKR's Courses | Course Web Sites | EOS Home ]
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Forward Modelling GPR Response Over Dry Volcanic Facies: Testing the Suitability of GPR Mapping at Santorini Volcano
By
Wendi Milner
Faculty of Applied Science
The University of British Columbia
April, 1997
Abstract
Ground Penetrating Radar (GPR) is a shallow geophysical tool that applies reflecting electromagnetic (EM) waves to imaging subsurface. GPR is ideal for mapping geology in areas of little topography and few outcrops. As such, this paper examines if the phases of Bronze Age eruption of Santorini Volcano that destroyed the Minoan culture and civilization (~1468 BP). Radar data and stratigraphic sections were recorded at a bench in Phira quarry, Santorini.
The Bronze Age Minoan eruption was a Plinian type eruption (Sparks and Wilson, 1990; Kalogeropoulis and Paritsis, 1989) with a number of phases, each phase (Figure 3) forming a unit identifiable in the geologic record. The units exposed at Phira quarry include basement Pre-Bronze Age deposits, Phase 1 unconsolidated airfall, Phase 2 laminated surge deposits, and Phase 3 massive pyroclastic flow (Russell and Stasiuk, 1995).
The Pulse-EKKO 100 Sensors and Software GPR unit to collect CMP and common off-set profiles. Frequencies of antennas used in these surveys were 50 MHz and 100 MHz and transmitter voltages used were 400V and 1000V. The data collected with 1000 V transmitter and 50 MHz antennae provided the greatest depth penetration and was therefore used for lithologic interpretation. Each phase of the eruption was recognizable in the radar data. Lithologic contacts, including the Minoan living surface, were also identifiable.
Velocity analysis was performed by examining hyperbola tails, CMP data, and lithologic correlation. An average bench velocity is 0.10 m/ns plus or minus 0.01 m/ns. This corresponds to a 0.2 m error in depth interpretation.
In addition, synthetics were created via forward modeling which were compared to processed GPR data. Synthetics confirm that GPR may be used to locate and explore the Minoan living surface. Electrical parameters of the Minoan deposits were derived to be as follows. Between 0 m and 50 m, k' (dielectric constant) is between 6.0 and 7.4 (v between 0.12 and 0.11 m/ns). At 68 m, k' is 13.2 (v=0.08 m/ns). Basement k' between 8.1 and 8.4 (v between 0.11 and 0.10 m/ns).
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Characterization of Volcanic Deposits with Ground Penetrating Radar
AUTHORS: J. K. Russell & Mark V. Stasiuk
JOURNAL: Bulletin of Volcanology (1997)
Abstract
The determination of the distribution, thickness and character of surficial volcanic deposits is often complicated by a combination of poor exposure and rapid facies variations. Ground-Penetrating Radar (GPR) is a portable geophysical technique that allows relatively rapid data aquisition and can provide critical supplementary information. The potential of the technique for use in volcanology, in terms of depth of penetration and correspondance between received signal and deposit character, is shown using data collected from traverses over four well-exposed, Recent volcanic deposits in western Canada. The deposits comprise a dacite airfall pumice deposit 3.5 m thick, a basalt lava flow 3-6 m thick, a dacite pyroclastic flow deposit 15 m thick, and an internally stratified dacite pumice talus deposit 60 m thick. Data were collected via a pulseEKKO IV GPR system with a focussed signal of dominant frequency 100 MHz. Other conditions varied: i) station spacings were 0.5-2.0 m, ii) time windows were 512 or 2048 ns, iii) the number of stacks was 64-512. The results show that GPR is an effective means of delineating major stratigraphic contacts and hence thicknesses. Also resolved were more subtle internal features, such as fractures in the basalt lava and internal stratigraphy in the pyroclastic deposits. In addition, large blocks in the pyroclastic deposits are detectable as distinctive point diffractor patterns in the profiles, showing that the technique has potential for providing grainsize information. Also reported are laboratory measurements of the dielectric constants of small samples of the main rock types, basalt lava and dacite pumice, in order to compare with the bulk deposit dielectric constants inferred from the field data. The bulk dielectric constants are significantly different from the sample values, especially for the pyroclastic deposits. This indicates that the utility of GPR at any site can be improved by initial calibration at well-exposed locations.
FIGURES: Figures can be viewed with captions.
FTP: Complete copy can be obtained via e-mail russell@perseus.geology.ubc.ca
[ Publications Home | JKR's Home | Igneous Petrology Lab ]
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Side-Looking Airborne Radar
Table of Contents
 Background
 Extent of Coverage
 Acquisition
 Data Characteristics
 Spatial Resolution
 Spectral Range
 Data Organization
 Data Availability
 Procedures for Obtaining Data
 Products and Services
 Applications and Related Data Sets
 References
 Appendix
Background
In 1980, the U.S. Geological Survey (USGS) began the Side-Looking Airborne Radar (SLAR) program. SLAR is an electronic image-producing system that derives its name from the radar beam transmission being perpendicular to the path of the aircraft during data acquisition. The result is an obliquely illuminated view of the terrain that enhances subtle surface features. SLAR is an active sensor; the system provides its own source of illumination in the form of microwave energy. Consequently, imagery can be obtained either day or night. Since microwave energy penetrates most clouds, SLAR can be used to prepare image maps of cloud-covered areas.
SLAR imagery is available from the USGS for selected project areas in the conterminous United States and Alaska.
Extent of Coverage
SLAR imagery is available for selected project areas in the conterminous United States and Alaska.
Acquisition
Side-Looking Airborne Radar (SLAR) images are acquired by transmitting a beam of microwave energy to the ground at an angle perpendicular to the aircraft's flight path. A portion of the energy that is reflected from the terrain is collected by the aircraft's radar receiver and is recorded as digital gray levels.
Data Characteristics
Spatial Resolution
Commercial SLAR systems produce images having a constant range and azimuth resolution of approximately 10 by 15 meters or better. However, resolution and deductibility are not synonymous; some objects smaller than one meter in size may be routinely detected because of their strong radar return. The look direction of a SLAR image (for example, west-looking) refers to the illumination direction. The choice of SLAR project design parameters such as look direction and beam angle is usually based on the topographic relief and trend of the area.
Spectral Range
Most commercially available SLAR systems operate in the X band frequency range of 12.0 to 8.0 gigahertz (GHz) or at wavelengths of 2.4 to 3.8 centimeters. Usually these systems transmit and receive a horizontally polarized signal (HH). Experimental radar systems, designed to aid in the development of satellite-borne units, operate in one or more frequency ranges and have vertical polarization capabilities as well.
Data Organization
SLAR project areas correspond to the coverage of one or more 1:250,000-scale topographic maps of the U.S. Geological Survey. Each 1:250,000-scale area is generally 1 by 2 degrees for the conterminous U.S. and 1 by 3 degrees for Alaska.
Data Availability
Procedures for Obtaining Data
To place orders and to obtain additional information regarding technical details and pricing schedules, contact: Customer Services, EROS Data Center
Online requests for these data can be placed via the USGS Global Land Information System (GLIS) interactive query system. The GLIS system contains metadata and online samples of Earth science data. With GLIS, you may review metadata, determine product availability, and place online requests for products.
Products and Services
SLAR images most often consist of image strips and 1:250,000-scale map-controlled mosaics. All Image strips and mosaics are available on high resolution film. The majority of image strips are also available on computer compatible tapes (CCT's); a limited number are distributed on compact disc read only memory (CD-ROM). SLAR Indexes on paper, film, or microfiche; mission flight logs and final project reports, and custom photographic products are also available. For more specific product information, see the APPENDIX at the end of this guide.
Applications and Related Data Sets
SLAR data are particularly useful when used with traditional earth science and other remotely sensed data. Scientists have effectively used SLAR data to map geologic features, explore for mineral and energy reserves, and identify potential environmental hazards.
References
U.S. Geological Survey, Earth Science Information Center, 1992, Side-looking Airborne Radar: Earth Science Information Center Factsheet, 2p.
U.S. Geological Survey, Earth Science Information Center, 1992, Side-lookingAirborne Radar (SLAR) Data on CD-ROM: Earth Science Information Center Product Announcement, 2 p.
U.S. Geological Survey, EROS Data Center, 1986, SLAR Side-looking Airborne Radar: National Mapping Program, p.1-4.
Appendix
 SLAR Film Products
 SLAR Digital Products
 Header Record
SLAR Film Products
Photographic strip images are available in 1:250,000 scale or 1:400,000 scale depending on the project.
Mosaics, produced from strip images, are a third generation photographic product and may have less resolution than the original strip imagery. In addition, shadow differences may occur across junction lines between adjoining strips. These differences may result in misinterpretation of apparent terrain relief. Mosaics are available in 1:250,000 scale, 1:100,000 scale or 1:50,000 scale depending on the project.
Users interested in acquiring SLAR products from the USGS can review the data by ordering SLAR Reference microfiche from the EROS Data Center. Most SLAR coverage areas are displayed on the microfiche.
SLAR Digital Products
Digital files allow for more detailed interpretation than photographic copies. The dynamic range of an 8-bit per pixel digital file is 15 times greater that that of photographic emulsions.
A SLAR CCT is an unlabeled or an ANSI Standard labeled tape having fixed-length records. The SLAR CCT file consists of data for one image strip (frame) of the project area. The first record in a CCT file is the ASCII header record (a detailed description is given under Header Record Format). The length of the header record is the same length as the image data records in the file. After each file on a CCT, a SINGLE tape mark indicates the end of the file; two tape marks indicate the end of volume. The image is in raw byte(8-bit) format.
A SLAR CD-ROM disc holds digital files of SLAR data strips for an entire 1-degree by 2-degree map area. The label files (*.LBL) in the images subdirectory are IMDISP-executable label files containing the required file information and path names to the data files themselves. The data files (*.DAT) are 8-bit binary files with the exception of the first block (line) of data, which is the standard SLAR ASCII header record (a detailed description is given under Header Record Format). Generally, the file naming convention is the 4-digit project area, 2-digit roll number, and 2-digit photographic frame number followed by the LBL or DAT extension.
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A Primer on Side-looking Airborne Radar
[From the README.TXT file on the demo CD]
Side-looking airborne radar (SLAR) images are so different from other types of remotely sensed data, in both mode of acquisition and techniques for interpretation, that a short explanation of important concepts and the use of this technology in the earth sciences will aid potential users.
SLAR is an electronic image-producing system that derives its name from the fact that the radar beam is transmitted perpendicular to the ground track of the aircraft acquiring the data. The result is an obliquely illuminated plan (or vertical) view of the terrain, a view that enhances subtle surface features and facilitates geologic interpretation. This enhancing characteristic is one of the reasons why SLAR imagery is so useful to earth resource scientists and managers involved in mineral and energy exploration, earth hazards studies, and diverse other geologic, hydrologic, cartographic, and engineering applications.
Another important property of SLAR is that it is an active system that provides its own source of illumination in the form of microwave energy; thus imagery can be obtained either day or night. Since SLAR penetrates most clouds, it can be used to prepare image-base maps of perpetually cloud-covered areas of the world where collecting conventional aerial photographs is impractical, such as over the rain forests of Brazil or along the Aleutian Arc of Alaska. Precise topographic mapping is more difficult to accomplish with SLAR than with aerial photographs because of the unique geometry and the coarser resolution. At present, accuracies of 30 meters in X, Y, and Z can be achieved, but only when specific criteria are met during data acquisition.
Since the radar signal is transmitted at a small depression angle below the horizontal plane in which the aircraft is flying, the signal strikes the terrain at a rather flat angle, and the surficial expression of the geologic structure may thus be enhanced. The topographic expression of some surface features, such as subtle faults and folds, may be more clearly seen on the radar image than on conventional aerial photographs or satellite images. For example, a depression angle ranging from approximately 10 to 40 degrees across the imaged swath is used for many earthscience applications. The change in depression angle across the imaged swath (a swath having a width of approximately 40 km is used by some commercially available systems) results in features nearer the flightline having shorter radar shadows than features of equal elevation farther from the flightline. Since SLAR is an active system, when a radar beam strikes a sufficiently elevated terrain feature, a radar shadow is cast by the feature; this is an area of no data return. The gradual change of shadow length across the range perpendicular to the flight path (and parallel to the width of the image swath) has resulted in the convention of designating the halves of the radar swath either near range, that half of the radar swath nearest the flightline; or far range, that half of the swath farthest from the flightline. Azimuth is the term used to describe the direction of the radar image parallel to the flightline, or the bearing of the flightline itself.
The SLAR products generally used for analysis are image strips and mosaics. SLAR images, whether photographic or digital, are the graphic representations of the SLAR data. Usually, the strips are much longer in azimuth than in range, since it is more efficient to fly long continuous flightlines. Photographic copies of the strips are generally regarded as better than photomosaics for interpretation for three reasons: they are at least one photographic generation closer to the original than subsequent products such as image mosaics; they can be viewed stereoscopically to give a three-dimensional impression; and strips are not usually as cosmetically altered to produce a pleasing composite image as mosaics. Digital files retain much more of the recorded dynamic range of the data than do photographic copies. For example, photographic images are generally limited to a dynamic range of about 15 db by the performance of the photographic emulsion; whereas an 8-bit-per-pixel digital file has an available dynamic range of 30-40 db.
SLAR mosaics provide a synoptic view of the terrain, but both the resolution and information content are slightly degraded in mosaic preparation. In addition, on mosaics, differences in length of shadow from terrain features, produced by the changes in depression angle across the range of the image swath, occur across mosaic junction lines between adjoining strips. These differences in length of shadow, as well as possible variations in the radar returns from similar features in near and far range, can result in misinterpretation of terrain and surface characteristics.
Positive photographic transparencies of image strips are generally considered superior to photographic paper for interpretation because the film has a greater density range and therefore contains more information. Digital files generally contain an even greater dynamic range of information. Because image strips generally have an overlap of 60 percent, both near- and far-range mosaics can be prepared by laying the respective halves of adjacent SLAR image strips side by side. These two SLAR presentations complement each other since the near-range data have less radar shadowing while the far-range data have more surface enhancement.
The look direction of a radar image refers to the illumination direction; for example, west looking means the radar beam was transmitted to the west. The choices of mission design parameters such as look direction and depression angle are usually based on an analysis of the geologic structure of the area. The parameters are then chosen to assure optimum data acquisition for the goals of the study. For example, linear structures such as faults that are parallel or nearly parallel to the range, or look, direction may not be easily detected since little radar shadow is present and enhancement is minimized.
In analyzing radar imagery, the image is oriented with the shadows on the side of the feature toward the viewer. "Shadows stab stomach" is the old adage used by radar interpreters. This practice assists in interpreting hills as hills and valleys as valleys.
Most commercially available SLAR systems operate in the X-band at frequencies of 8-12.5 GHz and wavelengths of 3.75- 2.4 cm. Usually these systems transmit and receive horizontally polarized signals (HH). Experimental radar systems, prototypes for the next generation of orbital imaging radars, are designed to acquire multifrequency and multipolarized data. Operating frequencies, other than X-band, include Cband at 4-8 GHz (7.5-3.75 cm), L-band at 1-2 GHz (30-15 cm), and P-band at 0.22-0.39 GHz (135-77 cm).
SLAR is a somewhat generic term for two distinctly different radar antenna technologies: real-aperture radar, also known as "brute force" radar; and synthetic-aperture radar (SAR), also known as coherent radar.
In a real-aperture system, a fan-shaped beam is transmitted, reflected by the surface, received, processed, and recorded as a line on the image. Because the angle of the transmitted radar beam is constant (for example, 0.45 degrees), the width of the beam is narrower in the near range than in the far range, and thus the azimuth resolution (parallel to the flightline) is better in the near range than in the far range. Resolution in the range direction (perpendicular to the flightline) is constant. Using our previous example, portions of the data in the near range would have a resolution of approximately 30x75 m in range and azimuth respectively, while portions of the far range would have a resolution of approximately 30x150 m.
Synthetic-aperture radar has constant range and azimuth resolutions through the image. This constancy is accomplished primarily by using more detailed information processing of the returned signal, thus simulating a longer antenna. A longer antenna produces a narrower radar beam, improving the resolution. Presently available synthetic aperture systems have nominal resolutions of 10x10 m or better.
It must be noted that resolution and detectability are not the same thing with radar; objects of less than 1 m size may be routinely detected because of the strong radar return of some features. Bright radar returns may be caused by such things as corner-reflector geometry, electrical resonance effects, or electronic interference.
SLAR data are particularly valuable when used in conjunction with traditional earth-science data, as well as with other remotely sensed data. Scientists from private industry, government, and university have effectively used SLAR all over the world to detect and map previously undiscovered geologic features that have contributed to the discovery of new mineral and energy reserves.
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Updated on 24 NOV 1995 D.L. Gustafson
GIS section home page
dlg@rivers.oscs.montana.edu
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