Impact of ionosphere on InSAR observation and coseismic slip inversion: Improved slip model for the 2010 Maule, Chile, earthquake

Satellite synthetic aperture radar (SAR) signals are affected by the Earth's ionosphere when the signals travel through the ionosphere. We first analyze the impact of ionospheric variation on the coseismic deformation results derived from interferometric SAR (InSAR) for the 2010 Maule, Chile, earthquake. We then jointly invert leveling, GPS and InSAR data for the coseismic slip distribution. The bias in the inverted slip distribution caused by the ionospheric variation is especially investigated. Our results show that mitigating the effect of ionospheric artifacts on long wavelengths, such as the L-band, InSAR data is critical to studying some strong earthquakes. It is therefore advisable at least as a precaution to check the level of significance of the ionospheric artifacts when studying strong earthquakes with InSAR, and when the artifacts are found to be significant, corrections for the artifacts should be applied. This research also indicates that megathrust rupturing occurred mainly at two asperities with peak slip magnitudes reaching 15.7 m and 9.8 m. More importantly, generally unlike the common existing understanding, our results show that the rupture reached the trench only in the northern segment of the trench (near 34.9 degrees S-35.4 degrees S).

Automated summary

The study shows that mitigating the impact of ionospheric artifacts on long wavelengths InSAR data is crucial for studying strong earthquakes. It is recommended to check the significance level of ionospheric artifacts when studying strong earthquakes with InSAR, and corrections should be applied if the artifacts are significant. Furthermore, the research indicates that megathrust rupturing mainly occurred at two high points with peak slip magnitudes of 15.7 meters and 9.8 meters, and contrary to common understanding, the rupture reached the trench only in the northern segment.