An Analysis Applying InSAR of Subsidence Caused by Nearby Mining-Induced Earthquakes

Abstract

Earthquake occurrence is usually unpredictable apart from sites in the vicinity of volcanoes. It is not easy to measure displacements caused by seismic phenomena using classical geodetic methods, which are based on point survey. Therefore, the surveying of ground movements caused by seismic events should be carried out continuously. Nowadays, remote sensing data and InSAR are often applied to monitor ground displacements in areas affected by seismicity. The effects of severe nearby mining-induced earthquakes have been discussed in the paper. The earthquakes occurred in 2017 and had a magnitude of 4.7 and 4.8. The distance between the epicenters of the mining-induced earthquakes was around 1.6 km. The aim of the investigation has been to analyze the spatio-temporal distribution of ground movements caused by the two tremors using the InSAR technique. Superposition of surface displacement has been studied in time and space. The main scientific aim has been to prove that in the areas where high-energy tremors occur, ground movements overlap. Due to proximity between the epicenters, the mining-induced earthquakes caused the formation of a large subsidence trough with the dimension of approximately 1.2 km × 4.2 km and total subsidence of ca. 116 mm. Two-time phases of subsidence were determined with temporal overlapping. The subsidence analysis has enhanced the cognition of the impact of mining-induced seismicity on the kinematics of surface changes. Moreover, the present work supports the thesis that InSAR is a valuable and adequately accurate technique to monitor ground displacements caused by mining induced earthquakes.

Analysis of the Geometry of Surface Deformations Caused by Induced Tremors in the Area of Underground Copper Mining

“…For example, (Malinowska et al, 2017) obtained the following values for the seismic event of 29 November 2016 (magnitude 4.5), vertical displacement of -80 mm, extent in the N-S direction 2.8 km and extent in the W-E direction 1.7 km, whereas (Milczarek 2019) determined the following values for the same tremor, vertical displacement of -80 mm, and extent of 2.7 km (in N-S direction) by 2.5 km (in W-E direction). Likewise, Hejmanowski et al 2019 analysed the 7 December 2017 and 26 December 2017 seismic events and the maximum displacement value obtained for the first tremor (−84 mm) is similar to the mean maximum displacement value in this study -83 mm, whereas the one for the latter tremor is greater (-116 mm) than our findings (-94 mm). The extents obtained are similar.…”

“…Numerous studies utilizing satellite radar interferometry for monitoring of surface deformations caused by hydraulic fracturing have been published, these include (Barba et al, 2016;Thorpe, 2017;Albano et al, 2017;Loesh and Sagan, 2018;Barnhart et al, 2018). In addition, similar research has been conducted in case of to hard coal mining (Krawczyk and Grzybek, 2018;Rudziński et al, 2019 ) and copper mining (Graniczny et al, 2017;Milczarek, 2019;Hejmanowski et al, 2019). Results of all of these studies indicate that various methods of satellite radar interferometry are suitable for detecting surface deformations caused by induced seismicity measured in the Line of Sight (LOS) of the satellite.…”

Tracking Deformation Processes at the Legnica Glogow Copper District (Poland) by Satellite InSAR—I: Room and Pillar Mine District

“…Despite this limitation, the sub-centimetric precision achieved by PSI analysis, allowed us to monitor the residual subsidence and to map the more moderate ground displacements surrounding several intense subsidence areas of limited sizes detected by the DInSAR classical approach. The latter therefore allowed us to identify the subsidence troughs that were previously recognized in the literature in LGCD and in other rooms and pillar mines [26,60]. In agreement with some authors (e.g., [28]), the results confirmed that the analysis of interferograms (Figures 5 and 6) represents an appropriate tool for detecting intense and fast terrain motions where the advanced multitemporal technique is no longer efficient.…”

“…Regarding mining-induced tremors (ii), an intense seismicity has been documented at LGCD (e.g., [24,25]): according to the local mining monitoring system and the national seismological survey carried out by the Institute of Geophysics in the Polish Academy of Sciences (IGF PAS), more than 2000 events with magnitudes between 0.9 and 3.5 are recorded yearly in this district [25]. The mining-induced earthquakes can cause the formation of large subsidence troughs occurring rapidly as a result of the release of seismic energy, with dimensions of a few square kilometers and total subsidence of the order of about 10 centimeters [26].…”

Induced Seismic Events—Distribution of Ground Surface Displacements Based on InSAR Methods and Mogi and Yang Models

“…In contrast to natural seismic events, source of induced tremors have an isotropic (non-double couple) character and a much lower force and affect areas which are several times smaller. To date, research on the application of SAR data to induced seismicity has focused mainly on the calculation of Line-of-Sight (LOS) displacements [15,26,27], and more sporadically on the calculations of vertical and horizontal displacements [28,29]. Our main goal was to verify whether synthetic aperture radar interferometry data allow for the calculations of the basic indicators (w-subsidence, T-trough slope, K-curvature, u-horizontal displacements, e-horizontal deformations) that describe a subsidence trough that has formed due to a mining tremor.…”