On 14th November 2016, the northeastern South Island of New Zealand was struck by a major Mw 7.8 earthquake. Field observations, in conjunction with InSAR, GPS, and seismology reveal this to be one of the most complex earthquakes ever recorded. The rupture propagated northward for more than 170 km along both mapped and unmapped faults, before continuing offshore at its northeastern extent. Geodetic and field observations reveal surface ruptures along at least 12 major faults, including possible slip along the southern Hikurangi subduction interface, extensive uplift along much of the coastline and widespread anelastic deformation including the ~8 m uplift of a fault-bounded block. This complex earthquake defies many conventional assumptions about the degree to which earthquake ruptures are controlled by fault segmentation, and should motivate re-thinking of these issues in seismic hazard models.One Sentence Summary: Major earthquake rips through evolving fault zone, defying conventional wisdom regarding the degree of fault segmentation during earthquake ruptures.

Optical Offsets 7To determine the co-seismic horizontal displacement field due to the Gorkha earthquake, we use optical 8 image correlation to measure the displacement of pixels between pre-and post-earthquake satellite im-9 ages. We are able to resolve sub-pixel displacements of less than 1/15th of the Landsat8 pixel resolu-10 tion (i.e. < 1 m) using the COSI-Corr software package images, which helps to increase the signal-to-noise ratio, (4) the deformation field is resolved perpendicular to 16 the look angle (i.e. the horizontal plane for nadir images), thereby providing measurements complementary 17to InSAR (which is sensitive to vertical displacements), (5) the nadir look angle is insensitive to topographic 18 residuals produced during orthorectification of the satellite images (such residuals are produced when a lower 19 resolution digital elevation model, DEM, is used during the orthorectification process), and (5) Landsat8 20 images are freely available from the USGS as an orthorectified product -see 5 for additional details. 21Landsat8 images are typically acquired at 10am each morning. Consequently, the illumination charac-22 teristics (i.e. shadows) vary in every image acquired throughout the year according to the position of the 23 sun. Because shadows produce sharp edges in satellite images, they strongly influence the correlation. There-24 fore, to reduce the effect of differing shadows biasing the displacement field, we correlate Landsat8 images 25 acquired at a similar time of year, thereby yielding images with similar illumination characteristics (i.e. sun 26 azimuth and elevation). In addition to having similar illumination characteristics, we also require images with 27 minimal cloud cover. From the Landsat8 archive, we found two suitable images from the (pre-earthquake) 2813th May 2014 (sun azimuth: 109• , sun elevation: 68

The interseismic strain across the Altyn Tagh Fault at 85°E has been measured using 59 interferograms from 26 ERS‐1/2 SAR acquisitions on a single track for the period 1993–2000. Using an atmospheric delay correction that scales linearly with height, we estimate the left‐lateral strike‐slip motion to be 11 ±1σ 5 mm/yr, assuming no relative vertical motion and a 15 km fault locking depth. This is in agreement with sparse GPS measurements. The atmospheric delay corrections agree well with coarse contemporaneous modelled weather data, reinforcing the importance of correcting for atmospheric delays in InSAR studies of interseismic strain accumulation, particularly in areas of high topographic relief that strongly correlate with the expected tectonic signal. We also find that, in addition to the tropospheric water vapour ‘wet’ delay, the hydrostatic ‘dry’ delay makes a significant contribution to the signal.