MALÅ GPR Resource Center

 

Advances in Borehole Geophysics for Ground-Water Investigations

Borehole radar provides a method to detect fracture zones at distances as far as 30 meters or more from the borehole in electrically resistive rocks. Fracture zones with electrical properties that differ from the surrounding nonfractured rock are excellent radar reflectors. Borehole radar has been successfully applied in granite, gneiss, and other crystalline rocks as well as in limestone and dolomite. Radar measurements can be made in a single borehole (transmitter and receiver in same borehole) or by cross-hole tomography (transmitter and receiver in separate boreholes).

Link: Advances in Borehole Geophysics for Ground-Water Investigations
 

Analysis of Borehole-Radar Reflection Data from Machiasport

For this investigation, a MALÅ Geoscience RAMAC radar system was used. The radar tool was configured with a broadband electric-dipole transmitting antenna and a dual-loop directional-receiving antenna with a three-component directional magnetometer. Both transmitter and receiver have center frequencies of 60 MHz in air. The center points of the antennas were separated by a common-offset distance of 6.41 m. Radar measurements were made every 20 centimeters (cm) along the open portion of each logged borehole. A total of 64 complete scans were stacked (averaged) at each measurement location to enhance the signal quality.

Link: Analysis of Borehole-Radar Reflection Data from Machiasport
 

Array GPR Investigation of the Cathedral of Uppsala

We present an example of a so-called array GPR investigation outside the Cathedral of Uppsala, Sweden. The aim of the investigation was to reveal historically interesting features in surroundings where excavations are not allowed. In the investigation, 17 different GPR antennae of the same frequency were used to obtain measurements in 16 parallel profiles simultaneously. When several separate transmitter and receiver antennae are combined into one single antenna array unit, exactly positioned parallel profiles are obtained, resulting in a seamless high-resolution 3D picture of the subsurface. Processing the radar data into the resulting images involves several steps, such as aligning traces, removing static shifts and matching the mean response. Radar data are merged with geometry data from a total station (used to track the position of the antenna array) and then gridded and migrated. In the Uppsala case presented here, the resulting pictures in the form of time slices gave archaeologists very valuable help in understanding the subsurface and mapping historical anomalies. The findings indicate former paths and early medieval streets, among other features.

Link: Array GPR Investigation of the Cathedral of Uppsala
 

Borehole radar investigations for subsurface characterization

The borehole radar system used in the investigation comprised a MALÅ CUII control unit with 250 and 100 MHz dipole antennas. Specially designed 20 MHz antennas were also used in one investigation for additional penetration. This MALÅ borehole system can be used in boreholes up to depths of 2500 meters. The antennas have a diameter of 48 mm, giving a borehole diameter of at least 56 mm or larger.The borehole radar surveys were performed in the dipole reflection mode and cross-hole mode. In reflection mode the radar transmitter

Link: Borehole radar investigations for subsurface characterization
 

Borehole Radar Measurements Technical Note

The RAMAC borehole radar system with 22MHz and 60MHz antennas for dipole mode and a 60MHz directional receiver were used for a geological site investigation for the HST railway route through Belgium and geological investigation for a salt mine in Germany.

Link: Borehole Radar Measurements Technical Note
 

Borehole Radar Survey To Explore Limestone Cavities For The Construction Of A Highway Bridge

During excavation work for the construction of a highway bridge in a limestone area in Korea, several cavities were found, and construction work was stopped temporarily. Cavities under the bridge piers might seriously threaten the safety of the planned bridge, because they could lead to excessive subsidence and differential settlement of the pier foundations. In order to establish a method for reinforcement of the pier foundations, borehole radar reflection and tomography surveys were carried out, to locate cavities under the planned pier locations and to determine their sizes where they exist. The GPR survey was to investigate shallow cavities, and to understand the distribution of basement rock. A RAMAC GPR system made by Mala Geoscience was used, and we acquired two data sets per survey line, one with 50 MHz and one with 100 MHz antennas.

Link: Borehole radar survey to explore limestone cavities for the construction of a highway bridge
 

Brief Company Presentation

MALÅ Geoscience is today the world leader in tools for non-invasive, non-destructive sub-surface investigations based on Ground Penetrating Radar technology. The video highlights three Company characteristics: 1. MALÅ Geosience's versatile product range covers a multitude of applications 2. Long experience in taking end-user products to the world market 3. Pro-active solution-oriented company with a talented R&D team enabling new application areas.

Link: Brief Company Presentation
 
 

Company Presentation

This presentation gives an in-depth report of a growing company with a world-wide sales presence. The company success stems from a long tradition of cutting-edge R&D. The video describes major characteristics of the company, explores the product portfolio and technologies used but also the key end user argument -- Ease of Use. We will hear some customers giving their view of the company, mentioning the value of quality in customer support and training.

Link: Company Presentation
 
 

Comparing Geophysical Methods For Talus Slope Investigations In The Turtmann Valley (Swiss Alps)

Three geophysical methods, ground penetrating radar, 2D-resistivity and seismic refraction were applied to two landform complexes in a high-alpine valley in Switzerland to investigate their internal structure. Results of the different methods were analysed separately, before conclusions about sediment thickness and geomorphologic implications were drawn. The results from the three methods were compared to focus on the quality of the methods and their field utility, with respect to portability of equipment, required man-power and measurement time. In this study, ground penetrating radar and seismic refraction proved to be the most suitable with respect to the quality and resolution of the subsurface information and the level of field utility. The GPR measurements for this study were performed by using a RAMAC GPR (Malå Geosystems). Data were acquired along a profile of more than 1200m long.

Link: Comparing Geophysical Methods For Talus Slope Investigations In The Turtmann Valley (Swiss Alps)
 

Crosshole Radar Tomography In An Alluvial Aquifer Near Boise Idaho

Ground penetrating radar (GPR) is often used to map stratigraphy in shallow aquifers. More recently, crosshole radar tomography is being used to characterize the spatial distribution of EM and hydrologic properties in the subsurface. A Mala Ramac Borehole radar system with 250 MHz antennas was used to acquire the data. The receiving antenna was held fixed in one well while the transmitting antenna was lowered in the other well. The transmitting antenna produced a signal at 0.05m intervals down the well. After this antenna reached the bottom depth the fixed receiving antenna was then lowered 0.2m, the transmitting antenna was raised to the top of the well, then lowered as before. The process was repeated until the receiving antenna had been lowered to the maximum depth. This geometry enables radar energy to repeatedly sample the space between the wells.

Link: Crosshole Radar Tomography In An Alluvial Aquifer Near Boise Idaho
 

Discrimination Mode Processing for EMI and GPR Sensors for Hand-Held Land Mine Detection

Signal processing algorithms for hand-held mine detectionsensors are described. The goals of the algorithms are to provide alarms to a human operator indicating the likelihood ofthe presence of a buried mine. Two modes of operations are considered:search mode and discrimination mode. Search mode generatesan initial detection at a suspected location and discriminationmode confirms that the suspected location contains a landmine. Search mode requires that the signal processing algorithmgenerate a detection confidence value immediately at the currentsample location and no delay in producing an alarm confidence istolerable. Search mode detection has a high false-alarm rate. Discriminationmode allows the operator to interrogate the entire suspectedlocation to eliminate false alarms. It does not require thatthe signal processing algorithm produce an alarm confidence immediatelyfor the current sample location, but rather allows thesystem to process all the data acquired over the region before producingan alarm. This paper proposes discrimination mode processingalgorithms for metal detectors (MDs), or electromagneticinduction sensors (EMIs), ground-penetrating radars (GPRs), andtheir fusion. The MD discrimination mode algorithm employs amodel-based approach and uses the target model parameters todiscriminate between mines and clutter objects. The GPR discriminationmode algorithm uses the consistency of detection as well asthe shape of the detection peaks over several sweeps to improve thediscrimination accuracy. The performances of the proposed algorithmswere examined on a dataset collected at a government testsite, and performance was compared with baseline techniques. Experimentalresults showed that the proposed method can reducethe probability of false alarm by as much as 70% at a 100% correctdetection rate and performed comparable to the best humanoperator on a blind test with data collected at approximately 1000locations.

Link: Discrimination Mode Processing for EMI and GPR Sensors for Hand-Held Land Mine Detection
 

Effects of Soil Physical Properties on GPR for Landmine Detection

Field experience has shown that soil conditions can have large effects on Ground Penetrating Radar (GPR) detection of landmines. We discuss available models for the prediction of the dielectric constant from soil physical properties including bulk density, soil texture, and water content. The soil dielectric constant determines the attenuation of the radar signal. The contrast between the dielectric constant of the soil and the landmine is critical in determining the strength of the reflection from the landmine. Field data show considerable spatial variability in soil water content over length scales from centimeters to kilometers. Even under the assumption that other soil properties are homogeneous, the spatial variability of soil water content can lead to large variations in the predicted dielectric constant and resulting GPR response.

Link: Effects of Soil Physical Properties on GPR for Landmine Detection
 

Efficient geological investigations using low frequency GPR

Geological knowledge from deep structures is most often needed when planning groundwater resources or out-takes of raw material for construction. In this case the use of low frequency radar systems can be both cost-effective and efficient way to obtain more knowledge of the subsurface conditions. By using a bi-static one-unit in-line antenna of 50 MHz these types of investigations have been made noticeably easier and can be handled by one operator, which cuts the costs. Several examples are given here of different types of geological investigations, down to a depth of approximately 20m.

Link: Efficient geological investigations using low frequency GPR
 

Enhancing Geotehcnical Information with Ground Penetrating Radar (GPR)

To learn how well ground penetrating radar (GPR) can supplement or replace conventional test borings a research project was initiated through New Hampshire’s State Planning and Research (SP&R) funding. The objective of the research was to determine if GPR could distinguish between and accurately determine the depth to different soil layers, bedrock, bedrock fractures, subsurface voids and river bottom profiles within different locations throughout New Hampshire. GPR profiles were obtained at locations between test borings or at locations where test borings could not be acquired because of time constraints or difficulties with drill rig access. To date, GPR has been used on a total of seventeen geotechnical projects as a supplement to the conventional test borings or as a sole source of subsurface information. This paper discusses the use of GPR on eight of these seventeen projects and includes projects where GPR was found to be very helpful, moderately helpful and projects were GPR was of little help. Included are the techniques employed for using GPR, and how the results were calibrated and verified.

Link: Enhancing Geotehcnical Information with Ground Penetrating Radar (GPR)
 

Evaluation of electrical methods, seismic refraction and ground-penetrating radar to identify clays below sands - Two case studies in SW Sweden

A clay layer below sand was investigated at two sites in southwestern Sweden. The objective was to test the effectiveness of four geophysical methods in mapping the upper and lower boundaries of buried clay. The Ramac GPR system from Malå Geoscience was used for the GPR survey. Unshielded antennae paced 2 m apart with a centre frequency of 50 MHz were used. All data were recorded with a sample frequency of 500 MHz.

Link: Evaluation of electrical methods, seismic refraction and ground-penetrating radar to identify clays below sands - Two case studies in SW Sweden
 

Geophysical Borehole Logging of the Borehole PH1 in Olkiluoto, Eurajoki 2004

Suomen Malmi Oy conducted geophysical borehole logging surveys at pilot hole PH1 at the Olkiluoto site in April 2004. The survey is a part of Posiva Oy’s detailed investigation program for the final disposal of spent nuclear fuel. The methods applied are magnetic susceptibility, natural gamma radiation, gamma-gamma density, single point resistance, Wennerresistivity, borehole radar and full waveform sonic. The assignment included the field work of all the surveys as well as interpretation of the acoustic and borehole radar data. The report describes the field operation, equipment, processing procedures, interpretation results and shows the obtained results. The data as well as the interpretation results are delivered digitally in WellCAD and Excel format.

Link: Geophysical Borehole Logging of the Borehole PH1 in Olkiluoto, Eurajoki 2004
 

Geophysical Detection Of Graves – Basic Background And Case Histories From Historic Cemeteries

This presentation reviews the three most commonly applied geophysical techniques and presents several case histories documenting the detection of graves. The main physical basis for grave detection is that grave shafts represent a disruption to the natural layering of the ground. Disruptions to soil layers can often be detected with GPR. Grave shafts represent a mixing of the soil types excavated, so there is usually a physical contrast of the grave fill with natural soil. Graves are often manifested by magnetic lows because they disrupt the natural fabric of soil magnetization and are also often delineated by resistivity lows, primarily because grave fill is not as dense as natural soil and can therefore retain higher moisture content. The basic conclusion is that grave detection is difficult, but usually achievable, especially when multiple techniques are applied.

Link: Geophysical Detection Of Graves – Basic Background And Case Histories From Historic Cemeteries
 

Geophysics Comes of Age in North American Archaeology

For many years, geophysics has been a routine part of archaeological investigations outside North America, especially in Europe and Japan, largely because massive stone foundations and sarcophagi are easier to map than ephemeral prehistoric features commonly found in North America. Recent technological advances in geophysical hardware and software now allow detection of subtle anomalies over these archaeological features and can provide the archeologist with invaluable information, especially in the cultural resource management environment. This paper presents data from several prehistoric and historic sites demonstrating the merits of this technology under typical North American conditions.

Link: Geophysics Comes of Age in North American Archaeology
 

GPR Investigations to Reconstruct the Geometry of the Wooden Structures in Historical Buildings

GPR applications to historical buildings have been cautiously increasing in recent years. The investigation of the wooden structural elements in historical buildings is essential to plan the restoration works. We discuss three case histories where 2D and 3D GPR surveys were executed to solve problems posed by restorers. The first survey was carried out to locate the beams of a wooden floor in a two hundred years old house in Pescate (Italy). The second survey was carried out in a stone masonry house of the 19th century in Lecco (Italy) to investigate the beam-wall connection. The third survey was carried out in a five hundred years old church in Busto Arsizio (Italy) to detect all the wooden elements. In this case some beams were totally hidden inside the brick and stone walls. In the last years the GPR has been increasingly adopted and applied for non-destructive evaluation of the inner wall structure. The great advantages of this technique are that it is completely non-destructive, the measurements can be performed quickly, the surveyed area is large and the resolution of high frequency antenna is enough to discriminate these targets.

Link: GPR Investigations to Reconstruct the Geometry of the Wooden Structures in Historical Buildings
 

GPR Phase-Based Techniques for Profiling Rough Surfaces and Detecting Small, Low-Contrast Landmines Under Flat Ground

In this paper, we present a new technique whereby phase variation signatures are used to profile two-dimensional (2-D) rough surfaces and to discern shallowly buried, small, low-contrast landmines under a flat ground. The method has been tested using data measured over a composite surface containing two rough dielectric surface patches, and over a flat ground under which small, low-contrast antipersonnel (AP) landmines are shallowly buried. The results show that the phase-based technique is capable of profiling rough surfaces and of detecting small, low-contrast landmines with different internal structures buried underneath a flat ground.

Link: GPR Phase-Based Techniques for Profiling Rough Surfaces and Detecting Small, Low-Contrast Landmines Under Flat Ground
 

GPR Rough Terrain Antenna Applications in Mineral and Groundwater Prospecting

As the RTA concept allows for a truly continuous towed approach to surveying, individual readings may be acquired rapidly at significantly much finer station spacings than is practical with conventional GPR systems. In applications such as paleochannel mapping for alluvial gold and diamond deposits, this increase in profile resolution yields a more accurate and representative interpretation.

Link: GPR Rough Terrain Antenna Applications in Mineral and Groundwater Prospecting
 

GPR Survey of Historic Masonry Arch Bridges Ponte de San Antonio, Cerdedo, Galicia

Ground Penetrating Radar (GPR) has been in use for archaeological purposes for more than two decades. Nowadays it has evolved into a powerful non invasive method to detect underground anomalies. The great advantage compared to other geophysical prospection methods, as i.e. magnetics, is that the data displays information about the depth of the found anomaly as well and this with a much better resolution than seismics can offer. With the appropriate software and knowledge about the ground composition, the object can be displayed 3-dimensionally. Monitoring of Masonry Bridges with GPR is a relatively new subject in cultural heritage. Most of the work has been done so far in Great Britain, mainly to determine load-carrying capacity of 19th century railway bridges. GPR in cultural heritage focuses on the detection of defects and inhomogenities in the structure, and to find out more about its composition. The overall goal is to determine the state of conservation to provide information in aspect of conservation and restoration.

Link: GPR Survey of Historic Masonry Arch Bridges Ponte de San Antonio, Cerdedo, Galicia
 

Ground Penetrating Radar Investigation of Ballast on the CN and CP Rail Lines near Ashcroft, British Columbia

This report details the work done to test the effectiveness of ground penetrating radar (GPR) as a tool to map variations in the thickness and quality of railway ballast and subgrade. The first part of the survey tested a section of Canadian Pacific Railway (CPR) track near Ashcroft, British Columbia using several antennas to determine which was most effective. A subsequent production survey on the CPR track focused on data collection with 250 and 500 MHz antennas, as these had been shown to be most effective. A third survey along Canadian National (CN) track near Ashcroft, B.C. collected data using only the 250 MHz antennas. AMCL used a system manufactured by Mala Geoscience that uses ground-coupled antennas. The frequencies chosen were 250-MHz, 500-MHz, and 800-MHz. The 250-MHz antennas were chosen as having the best penetration depth in a package that would fit between the rails. The 500 MHz and 800 MHz were chosen to test higher-resolution approaches.

Link: Ground Penetrating Radar Investigation of Ballast on the CN and CP Rail Lines near Ashcroft, British Columbia
 

Ground Penetrating Radar Study Of The Cheko Lake Area (Siberia)

We performed an integrated acoustic and GPR study of the Cheko Lake area (101o E, 62o N) during summer 1999. The GPR study aimed at imaging lake bottom and shallow sedimentary layers to plan coring of sediments coeval with the catastrophic 1908 explosion. The water of the Cheko Lake strongly attenuates radar waves. Therefore, the central and northern sectors of the lake (30 m average depth) were surveyed by means of acoustic techniques only. Integrated acoustic and GPR techniques were used in the shallow southern sector. More than 5 km of radar profiles were obtained in the lake, using 50 MHz and 100 MHz antennas. 150 metres of 200 MHz multi-fold profiles were obtained across the only accessible sectors on land. The GPR profiles processed to date successfully image discontinuities at depths greater than 700 cm. Comparison with acoustic results shows that GPR provides high resolution images of the depth range of interest (0-500 cm) which complement the information obtained from subbottom profilers and can be calibrated by the gravity cores.

Link: Ground Penetrating Radar Study Of The Cheko Lake Area (Siberia)
 

Helicopter-borne and ground-towed radar surveys of the Fourcade Glacier on King George Island, Antarctica

To determine subglacial topography and internal features of the Fourcade Glacier on King George Island in Antarctica, helicopter-borne and ground-towed ground-penetrating radar (GPR) data were recorded along four profiles in November 2006. Signature deconvolution, f-k migration velocity analysis, and finite-difference depth migration applied to the mixed-phase, single-channel, ground-towed data, were effective in increasing vertical resolution, obtaining the velocity function, and yielding clear depth images, respectively. For the helicopter-borne GPR, migration velocities were obtained as root-mean-squared velocities in a two-layer model of air and ice. The radar sections show rugged subglacial topography, englacial sliding surfaces, and localised scattering noise. The maximum depth to the basement is over 79 m in the subglacial valley adjacent to the south-eastern slope of the divide ridge between Fourcade and Moczydlowski Glaciers. In the ground- towed profile, we interpret a complicated conduit above possible basal water and other isolated cavities, which are a few metres wide. Near the terminus, the GPR profiles image sliding surfaces, fractures, and faults that will contribute to the tidewater calving mechanism forming icebergs in Potter Cove.

Link: Helicopter-borne and ground-towed radar surveys of the Fourcade Glacier
 

High Resolution GPR Imaging and Joint Characterization In Limestone

We focus on the application of Ground Penetrating Radar (GPR) to evaluate limestone characteristics of interest in environmental and engineering studies, and in particular: a) to image joints, bedding planes and cavities; b) to improve accuracy and resolution of the method; c) to evaluate joint/bedding planes characteristics which affect the radar response with particular reference to thickness, sedimentary infilling, water/clay content and spatial frequency. We used an ultra-wide band (UWB) system (RAMAC, Malå Geoscience) equipped with bow-tie shielded (250, 500MHz) and resistively loaded unshielded linear dipole antennas (50, 100, 200 and 400 MHz). A distance triggering device based on an electro-mechanical odometer was used to ensure constant 5 cm trace spacing. Average positioning accuracy was below 0.2%. Conventional single-fold methods were used in reconnaissance surveys at all test sites.

Link: High Resolution GPR Imaging and Joint Characterization In Limestone
 

High-Resolution Seismic And Ground Penetrating Radar–Geophysical Profiling Of A Thermokarst Lake In The Western Lena Delta, Northern Siberia

High-resolution seismic and ground-penetrating-radar (GPR) data have been acquired over Lake Nikolay in the western Lena Delta in order to study the uppermost basin fill and the bordering frozen margins. GPR (100 MHz antenna pair) measurements were completed on the frozen lake and its permafrost margins, while high-resolution seismic data were acquired from the lake during open-water conditions in summer using a 1.5–11.5 kHz Chirp profiler. The combined use of the two profiling systems allows stratigraphic profiling in both frozen and unfrozen parts of the lake. Shallow seismic reflection images of the uppermost 4 to 5 m of sediments are compared to GPR sections, which have approximately the same horizontal and vertical resolution. Short sediment cores aid calibrate the geophysical data.

Link: High-Resolution Seismic And Ground Penetrating Radar–Geophysical Profiling Of A Thermokarst Lake In The Western Lena Delta, Northern Siberia
 

Hydrogeologic Framework in Three Drainage Basins in the New Jersey Pinelands, 2004-06

During 2004-05, a hydrogeologic database was compiled using existing and new geophysical and lithologic data including suites of geophysical logs collected at 7 locations during the drilling of 21 wells and one deep boring within the three study areas. In addition, 27 miles of ground-penetrating radar (GPR) surface geophysical data were collected and analyzed to determine the depth and extent of shallow clays in the general vicinity of the streams. On the basis of these data, the Kirkwood-Cohansey aquifer system was divided into 7 layers to construct a hydrogeologic framework model for each study area.

Link: Hydrogeologic Framework in Three Drainage Basins in the New Jersey Pinelands, 2004-06
 

Inside a Mound: Applied Geophysics in Archaeological Prospecting at the Kings’ Mounds, Gamla Uppsala, Sweden

A combined geophysical prospection with slingram, gradiometer and ground-penetrating radar is described. The prospection is carried out at the Eastern Mound and the Thing Mound, Gamla Uppsala, Middle Sweden in an attempt to detect the internal structure of the mounds. At the Eastern Mound we were able to identify the fossil ground surface, a centre cairn, a possible older grave under the mound and a few other anomalies, some of them most possibly depending on historical activities and some more likely on prehistoric, human activities. The Thing Mound was found being of geological origin and only prepared to become a grave. The project shows that a combined use of several geophysical methods improves and simplifies the interpretation.

Link: Inside a Mound: Applied Geophysics in Archaeological Prospecting at the Kings’ Mounds, Gamla Uppsala, Sweden
 

Looking inside Turtle Mountain: Mapping fractures with GPR

This report describes the processing and analysis of geophysical data acquired in May and July, 2004, at the summit of Turtle Mountain, Crownest Pass, Alberta. Here, we discuss the ground penetrating radar (GPR) data only. The results of the seismic survey may be presented in a future report. Four GPR data sets were acquired at different locations at the summit of Turtle Mountain.

Link: Looking inside Turtle Mountain: Mapping fractures with GPR
 

MALÅ 3D Vision

MALÅ 3D Vision is a Windows® based software program for the processing and visualization of MALÅ Ground Penetrating Radar (GPR) data.

Link: Download PDF
 

MALA 3DVision

This manual is written for the end user of MALA 3DVision and explains how to set up and configure the product, as well as providing detailed instruction on its use. Basic theory for Ground Penetration Radar is outlined to help the operator understand the underlining technology. References for thorough discussions of this topic and applications for the technology are also presented. Known issues and limitations, precautions, best practices and tips are also presented so that the most efficient and productive use can be achieved.

Link: View online manual
 

MALÅ Bolehole Antennas

The MALÅ Borehole Antennas are powerful antennas, often used to obtain information at greater depths than is obtainable with surface GPR. MALÅ Geoscience manufactures the only commercially available borehole GPR system that can perform surveys deeper than 30 meters, due to the use of fiber optic cables for communication. In fact, the MALÅ Borehole Systems have been used successfully to depths in excess of 2500 m.

Link: Download PDF
 

MALÅ CX12 System

The MALÅ CX12 Concrete Imaging System is an easy to use, Ground Penetrating Radar (GPR) system designed for the non-destructive investigation and imaging of concrete and other structure.

Link: Download PDF
 

MALÅ Easy Locator HDR

This manual is written for the end user of MALA Easy Locator HDR and explains how to set up and configure the product, as well as providing detailed instruction on its use. Basic theory for Ground Penetration Radar is outlined to help the operator understand the underlining technology. References for thorough discussions of this topic and applications for the technology are also presented. Known issues and limitations, precautions, best practices and tips are also presented so that the most efficient and productive use can be achieved.

Link: View online manual
 

MALÅ Easy Locator System

The MALÅ Easy Locator is an easy to use, entry level Ground Penetrating Radar (GPR) system designed to meet your utility locating needs. The MALÅ Easy Locator is the tool of choice for those who need to quickly and easily identify the presence of buried utility infrastructure, both metallic and non-metallic.

Link: Download PDF
 

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MALÅ GPR Technology Explained

What is GPR and EM? This short presentation introduces the technologies used by MALÅ Geoscience in their GPR product range.

Link: MALÅ GPR Technology Explained
 
 

MALÅ GroundExplorer

The powerful MALÅ HDR technology provides the user with unmatched versatility and performance. Integration, ease of use and flexible configurations are a few of the features in the MALÅ GroundExplorer. Add to this the superior data quality, the resolution, and performance in MALÅ GroundExplorer over conventional GPR.

Link: Download Pdf-file
 

MALÅ GroundVision Software

MALÅ GrondVisionTM software is a data acquisition software designed by MALÅ Geoscience dedicated to MALÅ GPR Systems in single or multi-channel mode. The software is available as MALÅ GroundVision and MALÅ GroundVision 2.

Link: Download PDF
 

MALÅ HF Antennas

The MALÅ High Frequency (HF) Antenna series offers the best imaging solution with the highest resolution available. These antennas are primarily used for high precision measurements and surveys, such as Non-Destructive Testing (NDT), imaging of concrete and other structure, forensics, road surveys, layer thickness or other applications requiring high resolution measurements and images within the near surface shallow depths.

Link: Download PDF
 

MALÅ MIRA System

Traditional use of the GPR technology involves both single and multi-channel systems in many types of applications e.g. utility mapping, archaeological investigations, forensic investigations etc. When deploying ordinary GPR systems, the results suffer from lack of real 3D capabilities i.e. the line spacing in the surveys will, for practical reasons, be too large, meaning that information loss are inevitable. Also, reliable positioning of detected target cannot be made easy, neither in the data acquisition process nor in the reporting phase of a typical project. The MALÅ MIRA Systems are the first commercial systems designed to overcome these limitations.

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MALÅ MIRA System in Action

The MALÅ MIRA System were applied on the site of the ancient viking town of Birka. The purpose of the project was to map the burials and to give a more detail overview of the site. The site totally covered 30 000 m2. The MALÅ MIRA System surveyed the area with a grid spacing of 8 x 8 [cm] and with a survey speed of: 2500m2/hour.

Link: MALÅ MIRA System in Action
 
 

MALA Object Mapper

This manual is written for the end user of MALA Object Mapper and explains how to set up and configure the product, as well as providing detailed instruction on its use. Basic theory for Ground Penetration Radar is outlined to help the operator understand the underlining technology. References for thorough discussions of this topic and applications for the technology are also presented. Known issues and limitations, precautions, best practices and tips are also presented so that the most efficient and productive use can be achieved.

Link: View online manual
 

MALÅ Object Mapper Software

MALÅ Object Mapper software is a visualization software designed by MALÅ Geoscience dedicated for MALÅ GPR data. The software is best used with Object Mapper projects created with the MALÅ XV Monitor or the MALÅ CX System. MALÅ Object Mapper is developed to easily handle and interpret radar profiles acquired with the MALÅ XV Monitor or MALÅ CX System, where a number of radar profiles are linked to a common baseline.

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MALÅ Geoscience Corporate Headquarters in Malå, Sweden.

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MALÅ ProEx System

The MALÅ Professional Explorer (ProEx™) System is a modular, full-range Ground Penetrating Radar (GPR) system designed to meet the needs of the advanced professional user. At the heart of this system is the MALÅ ProEx Control Unit. Designed on a completely new technical platform, the MALÅ ProEx is the most versatile control unit in the MALÅ Geoscience range and replaces the World famous RAMAC/GPR CUII as the new high-end full range system.

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MALÅ ProEx System in Action

A MALÅ ProEx System is a versatile full range GPR system with features that no other GPR system can match. The MALÅ ProEx System is fully compatible with the broad range of MALÅ GPR Antennas and offer a flexible and versatile approach for GPR surveying, effeciently and in real-time.

Link: MALÅ ProEx System in Action
 
 

MALÅ RoadCart

The MALÅ RoadCart is a dedicated cart designed for high speed road measurements utilizing one or two shielded GPR antennas. The MALÅ RoadCart was designed in cooperation with experienced road investigation specialists to ensure safe and optimal performance at high speeds.

Link: Download PDF
 

MALÅ Roadway Mapper Software

The MALÅ Roadway Mapper software allows the user to define points of reference, based on GPS positioning, for selecting sections of road that are of specific interest for post-processing based on data already collected with the MALÅ ProEx RoadCart system.

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MALÅ RTA Antennas

MALÅ Rough Terrain Antenna (RTA) series changes the face of low-frequency Ground Penetrating Radar (GPR)surveying. The unique in-line, all-in-one, antenna design provides improved performance for deeper penetration. The flexible “snake” like design allows the antenna to be maneuvered easily and efficiently through the densest or most uneven of terrain without affecting ground contact, providing optimum results in the most difficult of environments.

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MALÅ Separable Shielded Antennas

MALÅ Separable Shielded Antennas offer the ability to separate transmitter antenna from receiver antenna. It is a feature which enables a user to study material parameters or perform special surveys, such as tomographic surveys. These antennas also lend themselves to optimise the antenna separation and vary polarisation patterns in order to better distinguish/characterize targets. Furthermore, a user may freely configure a multi-channel/multi-frequency array-type of system.

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MALÅ Shielded Antennas

MALÅ Shielded Antennas are designed for use in urban areas or sites with a lot of background noise. A MALÅ Shielded Antenna consists of both transmitter and receiver antenna elements in a single housing. The design ensures that the transmitted radar energy is only emitted from the bottom of the antenna housing, where it is in contact with the ground and protects the receiver element from external signals (noise) from directions other than the bottom of the housing, where it is located.

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MALÅ Unshielded Antennas

The MALÅ Unshielded Antennas consist of antennas with separate transmitter and receiver elements and electronics, allowing them to be operated in several modes for different survey techniques, such as reflection profiling, velocity profiling such as; common mid-point (CMP), or wide angle reflection and refraction (WARR), and also cross-scanning (tomography).

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MALÅ X3M System Animation

The MALÅ X3M System is the most compact GPR system on the market. It includes an integrated control unit, fitted directly on a shielded antenna and powered externally. The built-in electronic design makes the complete system a low weight and very compact system, easy to transport, assemble and operate. The convenience of this flexible and modular design means that a MALÅ X3M System can be quickly and easily configured for use across a wide range of mid-range applications.

Link: MALÅ X3M System Animation
 
 

MALÅ XV Monitor

The MALÅ XV Monitor is a dedicated data acquisition platform with a unique user interface designed for the MALÅ GPR systems. Traditionally, GPR systems have been operated from a notebook PC, however, MALÅ Geoscience has taken the initiative to introduce a powerful and dedicated tool that replaces this traditional approach and thereby offers several significant advantages.

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News: Archaeologists unearth Neolithic henge at Stonehenge

Archaeologists have discovered a second henge at Stonehenge, described as the most exciting find there in 50 years.

Link: BBC News
 
 

News: Ground penetrating radar work begins on potential Columbus cemetery site

Cultural resources Brockington and Associates have begun performing ground penetrating radar (GPR) work at the potential site of Columbus's original Black cemetery.

Link: WLTZ News
 

News: MALA GPR X3M assists Australian detectives in forensic search

Australian detectives use MALA X3M ground penetrating radar system to search for the remains of a man who went missing in March 2000.

Link: Sydney Morning Herald
 

News: Roman fort at Brancaster - MALA MIRA Ground Penetrating Radar data in motion

Exclusively for British Archaeology magazine (Mar/Apr 2013/129), Jimmy Adcock, archaeological geophysicist at GSB Prospection, describes the extraordinary data from MALA MIRA ground penetrating radar survey of Roman fort at Brancaster.

Link: British Archaeology - Roman fort at Brancaster
 
 

News: The GPR that discovered the second henge at Stonehedge

The story behind how MALÅ's MIRA GPR system helped archaeologists located a second henge. In Swedish. Read the English version http://tinyurl.com/second-henge

Link: SVT News
 

Pilot Study of the New Multichannel GPR System Mira For Large Scale, High-Resolution Archaeological Prospection at the Site of the Viking Town Birka in Sweden

In May 2008 the GPR manufacturer Malå Geoscience AB in collaboration with the archaeological prospection unit of the Swedish National Heritage Board conducted a large scale archaeological prospection pilot study with the recently launched Malå Imaging Radar Arrays (MIRA). Purpose of this project was to test the performance of the GPR and corresponding agricultural land use. Below the uppermost plough layer of approximately 35cm thickness a cultural layer of up to 2 metres thickness in central parts of the town, containing Viking age structures, can be expected to extend across an area of 15 to 20 hectares, the so called Black Earth of Birka.

Link: Pilot Study of the New Multichannel GPR System Mira For Large Scale, High-Resolution Archaeological Prospection at the Site of the Viking Town Birka in Sweden
 

Prediction of soil effects on GPR Signatures

In previous work we have shown that GPR signatures are affected by soil texture and soil water content. In this contribution we will use a three dimensional electromagnetic model and a hydrological soil model to explore in more detail the relationships between GPR signatures, soil physical conditions and GPR detection performance. First, we will use the HYDRUS2D hydrological model to calculate a soil water content distribution around a land-mine. This model has been verified against measured soil water distributions in previous work. Next, we will use existing pedotransfer functions (e.g. Topp, Peplinski, Dobson, Ulaby) to convert the predicted soil water contents around the land-mines as well as known soil textures and bulk densities into soil parameters relevant to the electromagnetic behaviour of the soil medium. This will enable a mapping between the hydrological model and the electromagnetic GPR model. Using existing and new laboratory and field measurements from the land-mine test facilities at TNO-FEL we will make a first attempt to verify our modelling approach for the prediction of GPR signatures in field soils. Finally a detection algorithm is used to evaluate the GPR detection performance with respect to changing environmental soil conditions.

Link: Prediction of soil effects on GPR Signatures
 

Scharffenbergbotnen (Dronning Maud Land, Antarctica) Blue-Ice Area Dynamics

Ground-penetrating radar (GPR) surveys in Scharffenbergbotnen valley, Dronning Maud Land, Antarctica, complement earlier, relatively sparse data on the ice-flow dynamics and mass-balance distribution of the area. The negative net surface mass balance in the valley appears to be balanced by the inflow. The flow regime in Scharffenbergbotnen defines four separate mass-balance areas, and about 60 times more ice enters the valley from the northwestern entrance than via the narrow western gate. We formalize and compare three methods of determining both the surface age gradient of the blue ice and the dip angles of isochrones in the firn/blue-ice transition zone: observed and dated radar internal reflections, a geometrical model of isochrones, and output from a flowline model. The geometrical analysis provides generally applicable relationships between ice surface velocity and surface age gradient or isochrone dip angle. The GPR survey with precise global positioning system (GPS) was made using a 50MHz Mala˚ Geoscience pulse radar. The objective of the survey was to track and date radar isochrones to map the mass balance in the valley, to determine the surface age gradient of the blue ice and to study the dip angles of the isochrones at the firn/blueice transition zone.

Link: Scharffenbergbotnen (Dronning Maud Land, Antarctica) Blue-Ice Area Dynamics
 

Setting up a GPR System for Road Evaluation

In this paper, we describe the steps required in order to adapt and complete a GPR system applied to road evaluation. Following some previous studies about the characteristics of the transmitted signal, we have directed our efforts towards both the design of an adapted vehicle and the integration of GPR data, together with other sources of information (GPS and video)

Link: Setting up a GPR System for Road Evaluation
 

Simple Method for Estimation of Water Content of Road Subbase using GPR

In this paper the possibility to measure moisture content in roadbeds using multi-channel GPR is described. GPR is a continuous and non-destructive method and its capabilities of providing information on soil and water content is well documented in the past. Most of these earlier described methods involve several time consuming measurements with a variety of antenna settings. A multi-channel radar system can however make more efficient measurements through the use of independently controlled transmitters and receivers in the antenna array. The purpose with this study is twofold. First, confirming previous results applied to roadbeds, and secondly, to find ways to apply this in a cost-efficient manner using multi-channel GPR equipment. This paper shows the preliminary results from the first part of this study. The Swedish National Road Administration (SNRA), Sweden, has funded this study. The system used for the field measurements was a RAMAC/GPR MC16, manufactured by MALÅ GeoScience AB. The system was equipped with an array of 4 identical antennas (4 transmitter and 4 receivers). Since the system allows the user to control each transmitter and receiver independently, a maximum of 16 channels of data can be recorded simultaneously.

Link: Simple Method for Estimation of Water Content of Road Subbase using GPR
 

Sinkhole Detection in Florida using GPR And CPT

This report details the work done to test the effectiveness of ground penetrating radar (GPR) as a tool to map variations in the thickness and quality of railway ballast and subgrade. The first part of the survey tested a section of Canadian Pacific Railway (CPR) track near Ashcroft, British Columbia using several antennas to determine which was most effective. A subsequent production survey on the CPR track focused on data collection with 250 and 500 MHz antennas, as these had been shown to be most effective. A third survey along Canadian National (CN) track near Ashcroft, B.C. collected data using only the 250 MHz antennas. AMCL used a system manufactured by Mala Geoscience that uses ground-coupled antennas. The frequencies chosen were 250-MHz, 500-MHz, and 800-MHz. The 250-MHz antennas were chosen as having the best penetration depth in a package that would fit between the rails. The 500 MHz and 800 MHz were chosen to test higher-resolution approaches.

Link: Sinkhole Detection in Florida using GPR And CPT
 

Studies Of Englacial Water In Storglaciaren Using Gpr - Year Two

This report describes the activities and preliminary findings of the second year of our project on Storglaciaren during the summer of 2002. Ice penetrating radar studies were used together with borehole video and other down-hole experiments to investigate englacial water flow. The radar surveys together with the borehole experiments suggest a new model for englacial drainage, wherein crevasse-like features are the main conveyors of water and form a fracture-like network consisting of numerous pathways, rather than the traditional view of a few melt-enlarged conduits in ice.

Link: Studies Of Englacial Water In Storglaciaren Using Ground Penetrating Radar
 

The Tulsa Race Riot of 1921: A Geophysical Study to Locate a Mass Grave

Geophysical studies at Oaklawn Cemetery have revealed two areas of subsurface features not correlated with surface features. One area contains one or more ferrous metal objects at a depth of at least 1 m. While it is possible that these ferrous objects could be indirectly associated with the Tulsa Race Riot (e.g., burial of weapons or shovels), their presence could predate the cemetery. Area 2 is a more promising location for a mass grave. The EMI quadrature and 500-MHz center-frequency GPR data are consistent with a previous excavation. Based on this information, a recommendation has been presented to the Tulsa Race Riot Commission that confirmatory excavation be performed. Radar studies were performed at two separate times with four different antenna pairs. All used the Mala Geoscience RAMAC system.

Link: The Tulsa Race Riot of 1921: A Geophysical Study to Locate a Mass Grave
 

Three-dimensional imaging of a deep marine channellevee/ overbank sandstone behind outcrop with EMI and GPR

A Mala GeoScience RAMAC/GPR system with 100-MHz center frequency antennae was used to collect the GPR data. Ten lines were collected, each separated by 1m. Each line started at the western boundary of the area and extended east for 70m. Each consecutive line was 1m north of the previous line and walked in the same direction. The antennae were rigidly fixed 1-m apart and oriented perpendicular to the collection line. This configuration is considered a collocated multimonostatic collection geometry. Collection of the GPR data along 10 lines produced 10 two-dimensional data sets. The regular spacing of the lines also allowed the data to form a 3D volume. Processing each of the 10 lines was performed with a 2D imaging algorithm based on geophysical diffraction tomography.

Link: Three-dimensional imaging of a deep marine channellevee/ overbank sandstone behind outcrop with EMI and GPR
 

Use Of Vertical-Radar Profiling To Estimate Porosity At Two New England Sites And Comparison With Neutron Log Porosity

Vertical-radar profiles (VRPs) and neutron porosity logs were acquired at two sites in New England – Haddam Meadows State Park in Connecticut and Massachusetts Military Reservation on Cape Cod. Both sites include boreholes drilled to depths of 30 to 50 meters into unconsolidated fluvial or glacial sediments. The VRP data are inverted using Tikhanov regularization to obtain interval radar propagation velocities. Of the two sites, the radar velocities at Haddam Meadows State Park show more variability with depth because this site consists of poorly sorted fluvial sediments, whereas the radar velocities at Cape Cod show much less variability because this site consists of well-sorted glacial sediments. In the field, VRP data are acquired using a Malå Geoscience1 RAMAC/GPR system with 100 MHz borehole antennas. The radar system employs fiber optic cables to connect the antennas with the control unit and thus eliminate cross talk and standing electromagnetic (EM) waves in the borehole.

Link: Sites And Comparison With Neutron Log Porosity
 

Using Ground Penetrating Radar for Assessing Highway Pavement Thickness

Surface distress is a fairly good indicator of rehabilitation needs but it does not directly relate to remaining life estimates. Mechanistic pavement design requires that strains be calculated utilizing more or less complex modeling. Over the years many devices measuring surface deflections under a given load have been developed. The device by choice for assessing strains due to load is the falling weight deflectometer (FWD). It creates an impulse load on the pavement surface. The data are commonly used in models for backcalculation of elastic moduli and strains. More complex modeling would involve finite element or dynamic element methods. The FWD method has proven to be an excellent tool for overlay design. For this purpose its simplicity and straightforwardness are well documented. However, to successfully backcalculate layer stiffness adequate layer thickness is needed. Thus there is a strong need for assessing layer data at testing points. Using Ground Penetrating Radar (GPR) it is possible to achieve data without coring. The present paper is a part of an ongoing bearing capacity study carried out by a regional road administration in central Sweden. Its objective is to optimize testing for equipment and methods used and presently available. In addition to evaluate the results from the study, the present paper discusses some other applications for GPR that may evolve from it.

Link: Using Ground Penetrating Radar for Assessing Highway Pavement Thickness
 

Velocity Analysis in the GPR Method for Loose-Zones Detection in the River Embankments

Determination of continuous distribution of the loose zones in the river embankment between points of geotechnical investigations is a very important matter for the embankment stability during the flooding. Presently, only non-invasive, geophysical methods can deliver such information. On the basis of numerous tests carried out by the Department of Geophysics at AGH University of Science and Technology in Cracow, the following conclusion may be drawn: zero-offset, reflection GPR profiling very seldom gives positive results at the detection of the loose-zones in the levee. Therefore, another concept of the loose-zones detection, using the GPR method, is presented in this paper. This technique is based on the modified CMP profiling, which allows to prepare a velocity map. Such a map may be used for evaluating of degree of the embankment disintegration.

Link: Velocity Analysis in the GPR Method for Loose-Zones Detection in the River Embankments