Physics

Geology

Foreshock

Mathematics

Episodic tremor and slip

Astronomy

Seismometer

Magnitude (astronomy)

Aftershock

Seismology

Slip (aerodynamics)

Interferometric synthetic aperture radar

Geometry

Subduction

Tectonics

Synthetic aperture radar

Moment magnitude scale

Remote sensing

Thermodynamics

Scaling

Scientific Reports

For tectonic earthquakes, slip rate spans a continuum from creep to supershear earthquakes, where slow slip events (SSEs) are important in releasing stress without radiating damaging seismic energy. Industrial-scale subsurface fluid injection has caused induced earthquakes, but the role of SSEs in fault activation is currently unclear. Ground-deformation observations, measured by satellite radar, show that SSEs up to magnitude 5.0 occurred during hydraulic fracturing (HF) operations in northwestern Canada, corroborated by reported deformation of the steel well casing. Although the magnitude 5.0 SSE exceeded the magnitude of the largest induced earthquake in this region (magnitude 4.55), it was undetected by seismograph networks. The observed SSEs occurred within a buried thrust belt and their magnitude and duration are consistent with scaling behavior of SSEs in unbounded natural systems, e.g. slab interfaces in subduction zones.

InSAR data reveal that the largest hydraulic fracturing-induced earthquake in Canada, to date, is a slow-slip event