A systematic study of earthquake detectability using Sentinel-1 Interferometric Wide-Swath data

This is a Preprint and has not been peer reviewed. The published version of this Preprint is available: https://doi.org/10.1093/gji/ggy426. This is version 1 of this Preprint.

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Authors

Gareth Funning , Astrid Garcia

Abstract

The Sentinel-1 mission comprises two synthetic aperture radar satellites, each with a 12 day orbital repeat, orbiting 6 days apart within a narrow tube. The mission design promises the ability to respond quickly to earthquakes with InSAR, and to facilitate production of interferograms with good interferometric correlation globally. We report on our efforts to study global seismicity using Sentinel-1 Interferometric Wide-Swath data between April 2015 and December 2016. We select 35 potentially detectable terrestrial earthquakes in the range 5.5 ≤ Mw ≤ 7.8 on the basis of their locations, depths and magnitudes, and process the first post-event interferogram with the shortest possible time-span for each using the ISCE software. We evaluate each interferogram for earthquake deformation signals by visual inspection.

We can identify deformation signals attributable to earthquakes in 18 of these interferograms (51%); a further six interferograms (17%) have ambiguous interferometric phase affected by tropospheric noise. 11 events (31%) could not be identified from their interferograms. The majority of these failed detections were due to interferogram decorrelation, particularly apparent for earthquakes that occurred between 15°N and 15°S, where climate conditions promote dense vegetation. The majority of the ambiguous interferograms are affected by tropospheric noise, suggesting that techniques to mitigate such noise could improve detection performance. The largest event we do not detect with Sentinel-1 data is a Mw7.0 earthquake that occurred in Vanuatu in April 2016; we also fail to detect the 2016 Mw6.2 Kurayoshi earthquake in one out of two possible 24-day interferograms. We propose these as upper and lower estimates on the magnitude of completeness for earthquakes studied with Sentinel-1 data; to lower the magnitude of completeness we suggest that more frequent (e.g. six day) recurrence may be necessary in low latitude areas.

DOI

https://doi.org/10.31223/osf.io/9wg8s

Subjects

Earth Sciences, Geophysics and Seismology, Other Earth Sciences, Physical Sciences and Mathematics

Keywords

InSAR, Sentinel-1, Earthquakes, detection, interferometric correlation, Space geodesy

Dates

Published: 2017-11-01 17:20

License

Academic Free License (AFL) 3.0

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