SUBSIDENCE DETECTION USING 
INTEGRATED MULTI TEMPORAL AIRBORNE IMAGERY 
R. D. Eyers *, J. P. Mills 
School of Civil Engineering & Geosciences, University of Newcastle, Newcastle upon Tyne, NE1 7RU, UK 
richard.eyers@ncl.ac.uk, j.p.mills@ncl.ac.uk 
Commission VII, WG VII/5 
KEY WORDS: Change Detection, Hazard, Hyper Spectral, Integration, Multi Temporal, Photography, Surface 
ABSTRACT: 
Multi temporal aerial photography and airborne hyper spectral imagery have been integrated for the detection and monitoring of coal 
mining subsidence hazards. Digital elevation models derived from successive epochs of aerial photography provide estimates of 
topographic change which may be indicative of the collapse of abandoned underground mine workings in the study area. Ground 
disturbed by subsidence can also be identified in hyper spectral imagery from soil moisture anomalies or vegetation stress. 
Archive photography originally acquired for topographic mapping over the last forty years was scanned and processed in a digital 
photogrammetric workstation. Since uncertainties in surface stability preclude the use of conventional ground control points for 
controlling historic photogrammetric models, each model was processed only to relative orientation stage. A control surface, created 
from a photogrammetric model comprising present-day imagery with contemporary ground control, was used in conjunction with a 
surface matching algorithm to provide the absolute orientation for each archive model. Subsidence features were then identified by 
subtracting the control DEM from each of the archive DEMs. 
Three epochs of airborne hyper spectral CASI and ATM imagery were acquired for the study area during a twelve month period. 
In the vegetated areas the Red Edge Position (REP) and parameters of the chlorophyll absorption feature were mapped. In the areas 
identified as exposed soil the thermal band of the ATM imagery is enhanced to show soil moisture variations. The results of the 
photogrammetric and hyper spectral processing were integrated to produce a subsidence hazard map of the study area. 
1. INTRODUCTION 
The collapse of workings in abandoned coal mines in the North 
East of England results in subsidence of the ground surface, 
disrupting agriculture and causing damage to buildings and 
infrastructure. Airborne remote sensing offers the potential to 
monitor the ground above abandoned mine workings and 
identify potential subsidence hazards. Subsidence may have a 
direct topographic expression due to underground collapse and 
an indirect spectral expression, due to the affect of the 
subsidence on surface hydrology and indirect affect on 
vegetation. Techniques from photogrammetry and hyper 
spectral image processing have been utilised to process airborne 
imagery acquired for an area of active subsidence in the 
Durham coalfield at Houghton-le-Spring. This area has been 
extensively undermined using both longwall and pillar and stall 
mining techniques, both of which can results in subsidence 
(Bell et al, 2000). The last coal mine in the area closed in 
1981. This paper discusses the application of airborne remote 
sensing in subsidence research and reviews progress that has 
been made in this area. 
1.1 Subsidence above abandoned coal mines 
The use of pillar and stall mining technique in the seams of the 
Durham coalfield has left a legacy of instability and subsidence. 
The potential for unstable ground conditions above abandoned 
  
* Corresponding author. 
pillar and stall workings is well documented, though the area 
has not received much attention (Taylor, 2002). This is distinct 
from the planned subsidence that occurs during longwall 
mining, with residual subsidence occurring within a year of the 
cessation of mining activities (Goulty, 1998). 
The deterioration of pillar and stall workings is difficult to 
quantify and a direct consequence of this is that subsidence may 
occur at any time. Gray and Bruhn (1982) stated that future 
subsidence above old workings cannot be ruled out even if 
subsidence has not been recognised within 50 to 100 years of 
the cessation of mining. 
1.2 Surface expression of subsidence 
Depressions form on the ground surface as a direct consequence 
of subsidence. Surface depressions or troughs can occur due to 
pillar crushing or failure (Taylor, 2002), the dimensions of 
which depend on a variety of factors including the depth of the 
workings and the overlying geology. In the Durham coalfield 
two distinct mechanisms of failure may be observed (Figure 1). 
In areas of exposed Carboniferous coal measures subsidence 
results in bowl-shaped depressions, the extent of which depends 
on the depth of the worked seam and the degree of collapse. A 
second mechanism of failure is observed in a significant part of 
the coalfields that is overlain by Permian magnesian limestone. 
In these areas subsidence is expressed as linear fissuring and the 
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