Abstract
Interferometric synthetic aperture radar (InSAR) measures surface
deformation from repeated passes of satellites or aircraft and has
become an important tool to study geophysical phenomena such as
earthquakes. However, InSAR data analysis is challenging due to
atmospheric water vapor that can mimic the effects of Earth deformation
and thus lead to wrong interpretations. We present preliminary results
on how to differentiate between tropospheric effects and surface
deformation from earthquakes using a convolutional neural network. As
earthquake training sets are sparse, our approach leverages transfer
learning techniques for tropospheric patterns from areas where
deformations are known to be mostly absent over short time periods, and
classifies specific areas of interferograms to reflect regions that are
dominated by deformation or tropospheric noise. The applicability of the
training set to a new area may depend on the similarity of the two
climates. Examples of tropospheric delays are shown from interferograms
constructed from Sentinel-1 data over part of southern California with
short temporal baselines, and examples of deformation are taken from
interferograms generated using Okada models. Our classifier is tested on
data from the 2018 Oaxaca earthquake in Mexico from Sentinel-1. This
work is a step towards using neural networks for a fine-granular
tile-based validation of interferograms and automatically removing
unwanted effects from InSAR signals, as well as towards enhancing the
agility of disaster response programs. The open source code is available
in the PyInSAR package on GitHub under the MIT license. We acknowledge
support from NASA AIST80NSSC17K0125 (PI Pankratius) and NSF ACI1442997
(PI Pankratius).