Induced Earthquakes from Long-Term Gas Extraction in Groningen, the Netherlands: Statistical Analysis and Prognosis for Acceptable-Risk Regulation

Effect of linguistic framing and information provision on attitudes towards induced seismicity and seismicity regulation

Shale gas is an expanding energy source worldwide, yet ‘fracking’ remains controversial. Amongst public concerns is induced seismicity (tremors). The UK had the most stringent induced seismicity regulations in the world, prior to instating a moratorium on shale gas development. The Government cited induced seismicity as the key rationale for its November 2019 English moratorium. Yet, little is known about how the public perceives induced seismicity, whether they support regulatory change, or how framing and information provision affect perceptions. Across three waves of a longitudinal experimental UK survey (N = 2777; 1858; 1439), we tested whether framing of induced seismicity influences support for changing regulations. The surveys compared (1) quantitative versus qualitative framings, (2) information provision about regulatory limits in other countries and (3) seismicity from other industries, and (4) framing a seismic event as an ‘earthquake’ or something else. We find low support for changing current policy, and that framing and information provision made little difference to this. The one strong influence on perceptions of seismic events came from the type of activity causing the event; shale gas extraction clearly led to the most negative reactions. We discuss implications for future UK policy on shale gas and geothermal energy in an evolving energy landscape.

Immediate and long-term health impact of exposure to gas-mining induced earthquakes and related environmental stressors

BACKGROUND

Little is known about the public health impact of chronic exposure to physical and social stressors in the human environment. Objective of this study was to investigate the immediate and long-term health effects of living in an environment with gas-mining induced earthquakes and related stressors in the Netherlands.

METHODS

Data on psychological, somatic and social problems recorded routinely in electronic health records by general practitioners during a 6-year period (2010-2015) were combined with socioeconomic status and seismicity data. To assess immediate health effects of exposure to ML≥1.5 earthquakes, relative risk ratios were calculated for patients in the week of an earthquake and the week afterwards, and compared to the week before the earthquake. To analyse long-term health effects, relative risks of different groups, adjusted for age, sex and socioeconomic status, were computed per year and compared.

RESULTS

Apart from an increase in suicidality, few immediate health changes were found in an earthquake week or week afterwards. Generally, the prevalence of health problems was higher in the mining province in the first years, but dropped to levels equal to or even below the control group in subsequent years, with lower relative risks observed in more frequently exposed patients.

CONCLUSIONS

From a public health perspective, the findings are fascinating. Contrary to our expectation, health problems presented in general practice in the earthquake province decreased during the study period. More frequently exposed populations reported fewer health issues to general practitioners, which might point at health adaptation to chronic exposure to stressors.

Application of a Small Baseline Subset Time Series Method with Atmospheric Correction in Monitoring Results of Mining Activity on Ground Surface and in Detecting Induced Seismic Events

The article presents the results of applying a Small Baseline Subset (SBAS) method to the monitoring of the influence of underground mining exploitation on terrain surface. Calculations were performed on the basis of two large SAR data sets. Calculations of time series additionally employed the Tymofyeyeva and Fialko empirical method for estimating atmospheric delay. A series of test calculations allowed verifying the potential of the method. The SBAS calculations were based on theoretical data prepared with the use of the Mogi model. This approach allowed simulating both underground mining exploitation and induced tremors. The results indicate that the model is useful in detecting sudden ground surface deformations. In such a situation, the image of a tremor can be observed in the atmospheric component. The actual data used in the analysis covered a region of underground copper ore extraction in southwest Poland. The calculations were based on SAR data obtained from the Sentinel 1A/B satellites, for the period between the end of 2014 and May 2018, from paths 22 and 73. In both cases, the total number of images exceeded 120. They served to calculate over 420 interferograms for each set. The results of ground surface displacements allowed precise identification of areas affected by underground mining activity. Over the acquisition period of six days, sufficient amount of SAR data was obtained to precisely monitor surface changes in the analyzed area. The employed empirical atmospheric delay reduction method was demonstrated to enable the detection of sudden ground surface changes due to mining tremors. This feature makes the method useful in detecting induced seismic events in areas characterized by intensive mining activity. It allows determining tremor locations in cases when acquisition dates are greater than the optimal value of 6–12 days (in the case of Sentinel 1A/B).