The largest ice calving event of a glacier caught on tape was the size of Lower Manhattan
A ice calving event means an event where a part of a glacier breaks off. The Jakobshavg Glacier in Greenland experienced a very large calving event which the photographer James Balog caught on tape. The event lasted for 75 minutes and it took out a piece of the glacier the size of Lower Manhattan. The calving face (the height of the ice face) was over 100 m tall. The whole event took 75 minutes. It was the largest ever filmed.
Here's a video of the beginning of the event. You should listen to it with high-quality earphones.