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Insar and Optical Constraints on Fault Slipduring the 2010–2011 New Zealand EarthquakeSequenceWilliam D. Barnhart, Michael J. Willis, Rowena B. Lohman, and Andrew K. MelkonianWilliam D. Barnhart, Michael J. Willis, Rowena B. Lohman, andAndrew K. MelkonianCornell UniversityEOnline material: Images of InSAR data, model residuals; tablesincluding offsets and resampled InSAR dataINTRODUCTIONOur study used space-based interferometric synthetic apertureradar (InSAR) and feature tracking on sub-meter-resolutionoptical imagery pairs to characterize surface deformationresulting from the 4 September 2010 Mw 7.1 Darfield,22 February 2011 Mw 6.3 Christchurch, and 13 June 2011Christchurch earthquakes (dates in local time), each of whichoccurred in the Canterbury region of the South Island ofNew Zealand. A rapid, coordinated international emergencyresponse is often required when strong-motion earthquakes hiturban areas. Unfortunately in these cases relief workers oftenhave little information about the location or the extent of damage.Remote sensing can rapidly provide maps of certain keyvariables (i.e., building damage, potential loading of nearbyfaults, etc.) to relief workers on the ground. These maps cancover broad areas on time scales that are only limited by therevisit time of the satellite or aircraft. Critically, imagery typessuch as satellite-based synthetic aperture radar (SAR) have longrepeat times of up to 46 days at present, although the existenceof overlapping tracks and multiple satellite platforms effectivelyreduces the repeat time somewhat. Here we demonstratethe impact of commercial optical imagery that can be acquiredwithin hours to days after an earthquake, with the goal of supportingrelief efforts in future earthquakes on a more rapidtimescale than can be achieved with SAR imagery alone. Wedemonstrate that these sub-meter-resolution scenes are feasibletools for deriving near-fault surface displacements for use infault slip inversions, even in areas of heavy agricultural activity.The Darfield and Christchurch earthquakes present anopportunity to observe postseismic deformation related to multiplemoderate (