Fig. 1.

(A) Location of Lake 028 and Lake 031 (red outlines). Sentinel-2 image from 2018-07-07 overlaid with the MEaSUREs 2017 velocity dataset (28) and contour lines from ArcticDEM (29) (Inset is location of Store Glacier in Greenland). (B) Lake 028 on 2018-07-07, $\sim$5 h prior to the onset of drainage, with instrument locations highlighted. (C) Lake 028 on the 2018-07-08 $\sim$4 h after peak drainage, with $\sim$1-km-long fracture marked with solid red line, and moulins marked as gray dots. Dashed red line marks the location of the healed 2017 crevasse in 2018. (D) Bed of fully drained Lake 028 on 2017-07-26, with maximum observed lake margin (from 2017-06-26) outlined with short-dashed black line. Location of the main drainage fracture (red line) is marked, and moulins marked as gray dots.