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Earth Explorer is an online source of news, expertise and applied knowledge for resource explorers and earth scientists. Sponsored by Geosoft.


News & Views

News Archive

December 7, 2016

Geosoft introduces IP and resistivity inversion in VOXI Earth Modelling

Geosoft has added induced polarization and resistivity data inversion to its VOXI Earth Modelling 3D inversion software service. Geoscientists are now able to create detailed 3D models of conductivity and chargeability from IP and resistivity survey data with VOXI. The resulting models can assist in interpreting and targeting regions for mineral and environmental applications...

December 5, 2016

Mexico's Deepwater Round Exceeds Expectations

Some of the world's biggest oil companies showed up Dec. 5 and agreed to invest on the Mexican side of the Gulf of Mexico, proving that deepwater exploration still has a pulse despite challenging market conditions...

November 30, 2016

Magnetic inversion results for Ngamiland available for download

A regional-scale geophysical inversion of magnetic field data in the Ngamiland region of northwestern Botswana is now available for download from the Botswana Geoscience Portal, a partnership initiative of the Botswana Geoscience Institute, industry sponsors and Geosoft...

November 30, 2016

LIGO Resumes Search for Gravitational Waves

After a series of upgrades, the twin detectors of LIGO, the Laser Interferometer Gravitational-wave Observatory, have turned back on and resumed their search for ripples in the fabric of space and time known as gravitational waves. LIGO transitioned from their engineering test runs to full science observations at 8 a.m. Pacific Standard Time on November 30...

November 9, 2016

International Volcano Scientists Unite

For the first time, the United States will host the international Volcano Observatory Best Practices workshop, previously held only in Italy. The workshop will take place this month in Vancouver, Washington. It is designed specifically for volcano observatories around the world and their staff to exchange ideas and best practices with each other...

October 4, 2016

USGS Assesses Mineral Potential for Sagebrush Habitats in Six Western States

USGS has completed a comprehensive assessment and inventory of potential mineral resources covering approximately 10 million acres of Federal and adjacent lands in Idaho, Montana, Nevada, Oregon, Utah and Wyoming...

October 3, 2016

Uganda Targets Up to U.S.$100 Million for Mineral Exploration

Uganda is well endowed with mineral resources and, like many naturally-gifted African countries, is becoming keen on ensuring that these resources play a transformative role in its long-term structural transformation dream - the Vision 2040...

September 9, 2016

Small-Scale Fishers Get A Big Boost With First-Of-Its Kind Impact Investment Fund

Conservation organization Rare announces the Meloy Fund for Small-Scale Fisheries at Our Ocean Conference. The Global Environment Facility, one of the largest funders of conservation worldwide, will be investing $6 million into the fund...

September 1, 2016

Scientists take to the skies to track West African pollution

Scientists operating research aircraft over West Africa have detected organic materials in the atmosphere over a number of urban areas, contributing to concerns of the rise in pollution across the region...

August 17, 2016

New IGS Xplore prospectivity maps for Botswana

International Geoscience Services have released a series of base metal prospectivity maps for the Ngamiland District of northwestern Botswana using free geodata available on the recently-launched Botswana Geoscience Portal, hosted by Geosoft. The maps identify favorable areas for copper, zinc and lead mineralization using geological, geochemical and geophysical datasets downloaded directly from the portal.

August 11, 2016

NexGen Makes New High Grade Discovery

NexGen Energy reported the discovery of a new high grade zone of mineralization 4.7 km northeast of the Arrow Deposit as part of an on-going summer drilling program on its 100% owned, Rook I property, Athabasca Basin, Saskatchewan...

August 10, 2016

Rampion UXO Disposal to Take Place This Week

E.ON has confirmed that the two unexploded devices, detected along the Rampion offshore cable route will be safely disposed this week following the consultation with the Marine Management Organisation...

August 9, 2016

Diamonds In The Rough: E&Ps Find New Reserves In Mature Basins

The oil industry’s history demonstrates clearly that new plays and prospects have long been found in mature basins that were thought to be well on the way to being squeezed dry. Through the acquisition of new data, developing new concepts and coming up with fresh interpretations, long-producing basins around the world from the North Sea to Malaysia have continued to reveal new riches...

August 8, 2016

Northern Shield Identifies High Quality VTEM Targets at Séquoi

Northern Shield Resources announced the results of the interpretation and modelling of the VTEM survey from the Séquoi Property in the Labrador Trough of Quebec . Séquoi is owned 100% by Northern Shield and is being explored for Noril'sk style Ni-Cu-PGE massive sulphides. After geophysical modelling and interpretation of the VTEM data from Séquoi, six VTEM anomalies of significant interest have been identified...

August 3, 2016

Rio Tinto tailors big data drive to copper

Rio Tinto will put the weight of an exploration big data push and its newly-formed Growth and Innovation group behind its desire to identify a "tier 1" copper asset. Speaking at the annual Diggers & Dealers conference in Kalgoorlie, Growth and Innovation group executive Stephen McIntosh said Australia was "overdue for a tier 1" mineral discovery of any type...

August 1, 2016

Tetra Tech Awarded $200 Million Navy CLEAN Contract

Tetra Tech announced that it has been awarded a $200 million, single-award contract by Naval Facilities Engineering Command (NAVFAC) Atlantic. Through the Comprehensive Long-term Environmental Action Navy (CLEAN) contract, Tetra Tech will provide environmental engineering support services to installations within the NAVFAC Atlantic Area of Responsibility...

May 3, 2016

NATO Science for Peace and Security (SPS), MODUM Partners announce "Young Scientist Summer School on Sea Dumped Chemical Weapons"

This international project cooperates closely with CHEMSEA (Search and Assessment of Chemical Weapons) Project for and sharing and knowledge transfer...

April 12, 2016

Monday mad rush for gold stocks

Renewed optimism about the outlook for gold saw investors pile back into gold stocks, pushing many stock to 52-week highs in heavy volumes...

April 11, 2016

Medgold Resources: Continues to Expand the Boticas Gold Project, Portugal; Proposes $200,000 Private Placement

Medgold Resources is pleased to announce new assay results from contiguous rock-chip sampling from the Limarinho South zone at its Boticas gold project in Portugal, which include a highlight of 6.0m @ 5.7 g/t Au...

April 8, 2016

De-carbonizing our energy sector

Nuclear energy currently provides around 11 percent of the world's electricity. China, the European Union, the United States, India, Russia, South Korea, and other nations’ have major existing fleets...

April 1, 2016

Follow-Up Drilling Results Indicate Wide Gold Zones at Hendricks Gold Discovery

Gascoyne Resources Limited announced that it has received the final assay results from the 10,000 metre aircore exploration drilling programme...

March 26, 2016

The Oil Market Is Finally Hitting Its Breaking Point

After a significant reduction in investments over the past two years, oil companies can no longer overcome the production declines from legacy wells...

March 15, 2016

N-Sea Expands into the French Offshore Wind Industry

Subsea IMR provider, N-Sea, has signed a letter of intent with CERES Recherches & Expertise Sous-Marine and TechSub Industrie Environement, to provide subsea survey, installation and remediation services to the French offshore wind industry...

March 9, 2016

PDAC 2016 Convention Exceeds 22,000 Attendees

Optimism and opportunity abounded at the PDAC 2016 Convention of The Prospectors & Developers Association of Canada in spite of recent industry challenges...

March 3, 2016

6 Alpha Launches EOD Contracting Division

6 Alpha Associates, a specialist risk consultancy practice, with expertise in the assessment and management of unexploded ordnance, has launched a dedicated explosive ordnance disposal division...

Treading delicate waters

by Virginia Heffernan on AUGUST 8, 2016 Technology

Tetra Tech's hovercraft-based electromagnetic system was used to detect likely munitions in the Caribbean, where shallow coral reefs had been excluded from a broader geophysical survey because of the potential for damaging the coral.

Tetra Tech's hovercraft-based electromagnetic system was used to detect likely munitions in the Caribbean, where shallow coral reefs had been excluded from a broader geophysical survey because of the potential for damaging the coral.

An example of the data collected with the TEMA-Lite (Tetra Tech towed electromagnetic array) system used on the hovercraft.

An example of the data collected with the TEMA-Lite (Tetra Tech towed electromagnetic array) system used on the hovercraft.

Tetra Tech uses hovercraft-based EM system to detect munitions around coral reefs

A hovercraft-based electromagnetic (EM) system has detected likely munitions at a location in the Caribbean previously used for target practice by the U.S. Navy. The area covers more than 200 acres of shallow coral reefs that had been excluded from a broader geophysical survey because of the potential for damaging the coral.

By using a hovercraft and a near zero draft sensor array, Tetra Tech was able to survey the vulnerable areas previously inaccessible except by more expensive and less sensitive helicopter based geophysical systems.

“We designed the system so it could be used in very shallow water where you can’t touch the bottom,” says Richard Funk, principal geophysicist for Tetra Tech’s Marine Mapping Group. “We can hover just a few inches over the coral and not damage it.”

The survey represents Phase 2 of a remedial investigation and feasibility study on one of several former defense sites in the Caribbean. The entire 1,030-acre site served as an impact range for aerial bombs, rockets, missiles, mortars and naval projectiles from 1903 until 1975.

Despite the challenges of wind, waves, hypersalinity and heat, Tetra Tech’s crew was able to collect accurate data because of the maneuverability of the hovercraft designed by Indiana-based Neoteric Hovercraft. Neoteric’s vehicle is the only model on the market with a reverse thrust system that allows the pilot to finely control the hovercraft while the sensors do their job.

“We had to be flexible, changing our plans based on wind direction and we were constantly having to maintain the system to keep everything running properly in a marine environment,” says Funk. “But it worked because the hovercraft was able to stand still on cushion.”

The team managed electromagnetic noise from the engine by placing the EM sensors at the front of the hovercraft. Other customizations included mounts for GPS antennas, detector batteries, and data collection consoles, computers and displays.

Following the successful deployment in the Caribbean, the team has other projects pending that will use the hovercraft-based system, not only for unexploded ordnance (UXO) detection, but for other purposes such as bathymetry, side-scan sonar, and sediment sampling, as well as laser mapping in wetlands and other delicate upland areas.

The Tetra Tech towed electromagnetic array (TEMA) system is an in-house design based on decades of Munitions and Explosives of Concern (MEC/UXO) detection and remediation experience. The system has two deployment configurations, each covering a 3-metre swath: the TEMA MK3, which is dynamically flown through the water column in depths from 3 to 100 metres; and TEMA-Lite (the system used on the hovercraft), which floats and can be pushed in extremely shallow water or towed on a sled mount to depths of about 40 metres.

The EM system is more effective than a magnetometer in developed areas because it is less susceptible to interference and signal masking from nearby piers and other large metallic structures. It also can detect both ferrous and non-ferrous metals, unlike a magnetometer.

Both TEMA configurations use the high power variant of Geonics EM61MK2 EM sensor, increasing detection ranges by 45-80% over the standard EM61MK2. On the TEMA-MK3 a fibre optic multiplexer streams high definition video live to the surface, allowing the crew to differentiate between visible debris and munitions. The multiplexor also sends data from the EM units, altimeters and heading and tilt sensors and still photos from a custom digital single-lens reflex (DSLR) underwater camera housing.

Funk and his team process the auxiliary sensor measurement data such as GPS locations using hydrographic survey software, and merge it with the EM data using Tetra Tech-developed software. The merged data are then imported into Geosoft Oasis montaj for processing, target detection and further analysis with the montaj UXO software extensions.

“Geosoft is the industry standard, so it’s easy for all the geophysicists in the company to share our data,” says Funk.


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