Locating the Scope and Depth of Coal Fires Based on Magnetic and Electrical Data.

Coal fires are a global environmental and social catastrophe, which deteriorate air quality, destroy the surface vegetation and soil, and pollute groundwater. The delineation of coal fire scope and the location of the fire source are indispensable for the efficient control of them. In this paper, three different geophysical methods, including magnetic method, self-potential method, and electrical resistivity tomography (ERT), are adopted to detect coal fires. Upward continuation is conducted with magnetic data and self-potential data to highlight the net anomaly due to coal fires and to suppress the noise from the background geomagnetic field and geoelectric field. The scope of the fires is delineated by magnetic and self-potential anomalies in 2D and is compared with the borehole temperature data. Furthermore, self-potential data is inverted by an iterative compaction constrained inversion algorithm with the assistance of resistivity data. The inverted fire source location, which is represented by the source current density, is consistent with field survey results. The findings are critical to determine the scope and source of underground coal fires. [ABSTRACT FROM AUTHOR]