Combining geomechanical modeling with physics-based seismicity models to assess the trigger probabilities of the Mw 5.5 2017 Pohang earthquake
Abstract
The hypocenter of the 15 November 2017, Mw 5.5 earthquake was close to an Enhanced Geothermal Systems site, where high pressure hydraulic injections had been performed during the previous two years and only two month before the event. The earthquake rupture was complex indicating the simultaneous activation of two different fault systems. Although first studies of the earthquake indicate that the event was possibly triggered or induced by hydraulic stimulations, a probability of such a scenario has not been given so far.
We adapt a probabilistic discrimination method previously developed for significant earthquakes close to depleted gas and oil fields for the problem of multiple hydraulic stimulation experiments. The method combines physics based seismicity models with hydro-geo-mechanical modeling of porous stress changes during and after fluid injections. It results in an estimate of the trigger probability for an observed event, where uncertainties of the geo-mechanical models and of seismological parameters are considered in a Bayesian approach. The applications to the Pohang earthquake is complex because different injection, bleed-off and shut-in phases were performed. We use the example to demonstrate the potential, strength and limits of the assessment method for future applications and risk assessments prior to injection experiments. H.H. has been supported by European Commission Horizon2020 project691728 DESTRESS- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.S23B0518D
- Keywords:
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- 7209 Earthquake dynamics;
- SEISMOLOGYDE: 7223 Earthquake interaction;
- forecasting;
- and prediction;
- SEISMOLOGYDE: 7230 Seismicity and tectonics;
- SEISMOLOGYDE: 8168 Stresses: general;
- TECTONOPHYSICS