Prof. Baoshan Wang
(University of Science and Technology of China)
Title
Migration of micro-earthquakes during cyclic operation of Underground Gas Storage and the Changdao earthquake swarm
Abstract
The distribution of earthquakes is controlled by the stress state and material properties. And the migration of earthquakes can be used to infer the changes in subsurface stress or medium properties. In this presentation, we will introduce two case studies of seismicity migrations related respectively to the Hutubi Underground Gas Storage (UGS) in Junggar Basin and the Changdao earthquake swarm occurred in the Bohai Sea. We first use the matched and filter technique to detect more events than the local catalog. And then we relocate the detected events using double difference method with waveform cross-correlation-based differential travel-times. Micro-earthquakes clearly migrate outward from the UGS during the cyclic operation, the migration may result from the stress transfer during multiple injection and extraction. The seismicity during Changdao earthquake swarm unilaterally migrated south-west accompanied by some bursts along several conjugate faults. We suggest that fluid diffusions are responsible for the earthquake migration in Changdao.
