Strain Accumulation and Release Rate in Canada: Implications for Long‐Term Crustal Deformation and Earthquake Hazards

Abstract

To advance the understanding of crustal deformation and earthquake hazards in Canada, we analyze seismic and geodetic data sets and robustly estimate the crust strain accumulation and release rate by earthquakes. We find that less than 20% of the accumulated strain is released by earthquakes across the study area providing evidence for large‐scale aseismic deformation. We attribute this to glacial isostatic adjustment (GIA) in eastern Canada, where predictions from the GIA model account for most of the observed discrepancy between the seismic and the geodetic moment rates. In western Canada, only a small percentage (<20%) of the discrepancy can be attributed to GIA‐related deformation. We suspect that this may reflect the inaccuracy of the GIA model to account for heterogeneity in Earth structure or indicate that the present‐day effect of GIA in western Canada is limited due to the fast response of the upper mantle to the deglaciation of the Cordillera Ice Sheet. At locations of previously identified seismic source zones, we speculate that the unreleased strain is been stored cumulatively in the crust and will be released as earthquakes in the future. The Gutenberg‐Richter model predicts, however, that the recurrence interval can vary significantly in Canada, ranging from decades near plate boundary zones in the west to thousands of years in the stable continental interior. Our attempt to quantify the GIA‐induced deformation provides the necessary first step for the integration of geodetic strain rates in seismic hazard analysis in Canada.

Three Mw ≥ 4.7 Earthquakes Within the Changning (China) Shale Gas Field Ruptured Shallow Faults Intersecting With Hydraulic Fracturing Wells

“…Although there may be additional reasons for the high level of HF-induced seismicity in Sichuan Basin, our reasoning is asserted by the following observations: (1) The regional tectonic environments in central US and western Canada with HF-induced seismicity (e.g., Kreemer et al, 2014;Ojo et al, 2021) do not include a zone of high strain accumulation manifest in GPS velocity gradients. (2) In the Sichuan Basin there is a correspondence between the seismicity rates and the distances from the southeastern margin of the Tibetan Plateau: The Changning and Jiaoshiba fields are nearest and furthest away, respectively, and are characterized with the highest and lowest levels of induced seismicity despite the annual yield of the Jiaoshiba field being larger than the Changning field.…”

Ionospheric Total Electron Content (TEC) Anomalies as Earthquake Precursors: Unveiling the Geophysical Connection Leading to the 2023 Moroccan 6.8 Mw Earthquake

“…The findings extracted from the closest station to the epicenter, RABT, provide compelling evidence of significant anomalies closely associated with the 6.8 Mw earthquake. In our quest to pinpoint the exact timing of peak anomalies, we employed Equations ( 4) and (5). The PPA was determined to occur on 2 September 2023 at 13.7 UTC, exhibiting a substantial difference of 10.449 TECU.…”

“…Understanding the intricate processes leading to an earthquake is crucial for early warning systems and disaster preparedness. Traditional earthquake prediction methods primarily rely on monitoring geological and seismological parameters, such as ground deformation [1][2][3], strain accumulation [4,5], lineament analysis [6,7], and seismic activity [8]. However, recent advances in the field of ionospheric science have opened new avenues for earthquake forecasting, offering complementary insights into the complex processes that precede seismic events.…”