Controls on plate motion by oscillating tidal stress: Evidence from deep tremors in western Japan

• Published in: Geophysical research letters Vol. 41; no. 11; pp. 3842 - 3850
• Main Authors: Ide, Satoshi, Tanaka, Yoshiyuki
• Format: Journal Article
• Language: English
• Published: Washington Blackwell Publishing Ltd 16.06.2014; John Wiley & Sons, Inc
• Subjects: Clusters; Correlation; deep tremor; Earthquake prediction; Earthquakes; Forecasting; Friction; large earthquakes; Nonlinearity; Oscillating; Periodicity; Plate motion; Plate tectonics; Plates (tectonics); Probabilistic methods; Probability theory; Records; Rheological properties; Rheology; Seasonal variations; Seasonality; Seismic activity; Seismic phenomena; Seismicity; Shear; Slip; Stress; Stresses; Temporal variations; tidal stress; Tides; Tremors
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1002/2014GL060035

Deep tremors are considered to be shear slip on the plate interface and are often sensitive to tidal stress. Here we demonstrate that a small cluster of tremors is extremely well correlated with tide levels observed at nearby stations in western Japan. The correlation is interpreted as representing a nonlinear relationship between stress and slip, which is similar to the rate‐dependent friction law. An empirical relationship and observed tide records explain the temporal changes in tremor activity over 9 years. The combination of the nonlinear fault rheology and oscillating tidal stress may control temporal changes in plate motion and earthquake occurrence. Remarkably, the background seismicity is similar to the predicted tremor rate obtained from tidal observations over the past 50 years. This mechanism may also explain the seasonality and decadal‐scale weak periodicity of large earthquakes and is likely to be helpful in probabilistic forecasting of future seismicity. Key Points A new catalog of tectonic tremors at the deep plate interface Strong evidence that oscillating tidal stress promotes deep plate motion Periodicity and seasonality of large earthquakes may also be explained