Surface Subsidence as an Effective Indicator of Methane Emissions From Underground Coal Mines

Abstract

Methane (CH ₄ ) emissions from underground coal mining remain a major and uncertain anthropogenic source. This study tests whether surface subsidence, a direct consequence of underground mining, can serve as an indicator of CH ₄ emissions. We use the Changzhi coal belt in Shanxi of China, a major emission hotspot, as a case study. Time‐series Interferometric Synthetic Aperture Radar analysis of Sentinel‐1 SAR data (November 2019 to October 2024) revealed persistent subsidence across the region. Over a similar period, hyperspectral images from four satellite platforms (March 2019 to October 2024) detected 568 CH ₄ plumes from 33 point sources. The two data sets showed strong spatial overlap. Annual subsidence volume was significantly negatively correlated with time‐averaged point‐source emissions ( r  = −0.65 to −0.53, p  < 0.01), indicating that subsidence, as a proxy for extracted coal volume, is a reliable indicator of cumulative emissions. Applying this hyperspectral‐calibrated relationship to areas with subsidence but no detected plumes yields total point‐source emissions of 0.288–0.508 Mt·a ⁻¹ , representing 13%–43% of regional inventory estimates. Hyperspectral satellites alone miss approximately 18%–32% of this total. Combining InSAR‐derived subsidence with hyperspectral plume observations thus provides a nearly all‐weather pathway for monitoring CH ₄ emissions from underground coal mining.