Microgravity method for detection of abandoned mines in New Jersey

Journal Article · Mon Mar 01 04:00:00 EST 1993 · Bulletin of the Association of Engineering Geologists; (United States)

DOI:https://doi.org/10.2113/gseegeosci.xxx.1.79· OSTI ID:6237347

Ghatge, S L ^[1]

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1. New Jersey Geological Survey, Trenton, NJ (United States)

The microgravity method has been used to detect two shallow, subsurface abandoned mines in northern New Jersey. Synthetic models simulated the expected gravity anomalies in the two areas. The first site, Lawrence Iron Mine, tested the applicability of microgravity for abandoned-mine detection. Two profile lines were laid out at right angles to the strike of the magnetite deposit in an amphibolite host rock. The broad gravity lows (magnitude 0.04 and 0.07 mGals) on the gravity profiles were modeled to show mine workings about 10 ft square and 5 ft deep that were filled with loose soil. Trenching confirmed the location of the buried mine. At the Schuyler Copper Mine, located in an urban area, data were collected along four parallel profile lines spaced 10 ft apart. An anomalous low (magnitude 0.03 mGals) on the gravity map was modeled and interpreted to be due to an empty vertical shaft. The shaft is more than 60 ft deep, about 12 ft long and 8 to 10 ft wide. It is capped by about 10 ft of unconsolidated material overlying sandstone bedrock. Drilling confirmed the results of the gravity model. The success of the method depended on the depth and size of the mine instrument accuracy, station spacing, station location and elevation control. Minimizing errors due to the instrument drift, station location and station elevation maximized the resolution of the technique.

• OSTI ID: 6237347
• Journal Information: Bulletin of the Association of Engineering Geologists; (United States), Journal Name: Bulletin of the Association of Engineering Geologists; (United States) Vol. 30:1; ISSN 0004-5691; ISSN AEGBBU
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
540250 -- Environment
Terrestrial-- Site Resource & Use Studies-- (1990-)
58 GEOSCIENCES
580000* -- Geosciences
ABANDONED SHAFTS
ABANDONED SITES
DATA ANALYSIS
DEVELOPED COUNTRIES
FEASIBILITY STUDIES
FIELD TESTS
GEOPHYSICAL SURVEYS
GRAVITY SURVEYS
HAZARDS
MINE SHAFTS
MINING
NEW JERSEY
NORTH AMERICA
SHAFT EXCAVATIONS
SURVEYS
TESTING
UNDERGROUND MINING
USA