Evaluation of Seismic Potential in a Longwall Mine with Massive Sandstone Roof Under Deep Overburden: An Update

Details

• Personal Author:
  Beale J ; Khademian Z ; Klemetti, Ted M. ; Van Dyke M ; Wickline J
• Description:
  In 2016, a 3.7-ML magnitude event caused by mining activity occurred at a longwall mine in southwestern Virginia which was recorded by the United States Geological Survey (USGS) and felt by local residents. The event was the largest of its kind since a global mine design change by the operator was instituted in 2008 following three large events in 2005, 2006, and 2007 (3.4, 4.3, and 3.4 Moment Magnitude (Mw), respectively). Two of the three pre-2008 events (2005 and 2007) damaged ventilation controls in the mine which fueled a mine fire. In 2016, the mine's management requested researchers from the National Institute for Occupational Safety and Health (NIOSH) to access geological data and determine what parameters could possibly lead to events of a magnitude of 1.0 ML or greater. Evaluation of 2152 geological data points and modeling revealed three major geological factors in common with the majority of the 181 recorded +1.0 ML events from 2009 through 2016. Three levels of seismic potential were identified as follows: Low potential (1.0+ ML): overburden greater than 579 m; Moderate potential (1.5+ ML): overburden greater than 579.12 m and 6.1-12.2 m of sandstone within 15.24 m above the top of the Pocahontas 3 coal seam; Elevated potential (3.0+ ML): overburden greater than 579.12 m, 6.1-12.2 m of sandstone within 15.24 m above the coal seam, and caving height of less than 4.5 m above the coal seam. These three factors were used to create a seismic forecast map that produced an accuracy of 74-89% for 1.0 ML or greater events, 72% accuracy for 1.5 ML or greater events, and 100% accuracy for 3.0ML or greater events based on seismic history. The map was created to not only show how geological data can be combined to understand why a mining-related seismic event occurred in a particular area, but how the map could be used to forecast potential seismic areas in future mining. This paper is an update to report the accuracy forecasting large seismic events in areas mined since the map was originally published in 2017 and how the map has helped improve miner safety and health based on its implementation. New changes to the forecasting process include implementing a change to the moderate potential criteria to expand the sandstone thickness to 4.6-12.2 m and decreasing the location error from a 91-m buffer to a 10% (58 m) elevation error based on the first overburden thickness threshold of 579 m. Since the first seismic forecasting map was published, the map has correctly forecasted 54-71% of 115 total 1.0-1.4 ML events, 69-83% of 49 total 1.5-1.9 ML events, and 88% of 9 total 2.0 ML or above events in previously unmined areas. [Description provided by NIOSH]
• Subjects:
  Coal Geology Mining Occupational Health Safety
• Keywords:
  Author Keywords: Coal Coal Mines Ground Monitoring Ground Stability Longwall Longwall Mining Seismic Underground Mining
• Series:
  Mining Publications
• ISSN:
  2524-3462
• Document Type:
  Text
• Genre:
  Journal Article
• Place as Subject:
  OSHA Region 3 ; Pennsylvania ; Virginia ; West Virginia
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Division:
  PMRD - Pittsburgh Mining Research Division
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Volume:
  40
• Issue:
  5
• NIOSHTIC Number:
  nn:20068232
• Citation:
  Min Metall Explor 2023 Oct; 40(5):1523-1533
• Contact Point Address:
  Mark Van Dyke, CDC NIOSH, Pittsburgh Mining Research Division, Pittsburgh, PA, USA
• Email:
  mso2@cdc.gov
• Federal Fiscal Year:
  2024
• NORA Priority Area:
  Mining ; Oil and Gas Extraction
• Peer Reviewed:
  True
• Source Full Name:
  Mining, Metallurgy & Exploration
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:e337213371846a72cc62c77e568608d79818e3dc8f6c58a09307c55db3adc519fd74e55c1d88b8618a974a17750cbfccc942f803083c28db7a74ba8135631037
• Download URL:
  https://stacks.cdc.gov/view/cdc/215655/cdc_215655_DS1.pdf
• File Type:
  [PDF - 2.43 MB ]