The 6.3 magnitude earthquake that struck New Zealand on Tuesday, killing at least 75 people in Christchurch, also shook loose 30 million tons of ice from the nation’s longest glacier, sending boulders of ice into a nearby lake.

Tour boat operators in the area said parts of the Tasman Glacier calved into the Tasman Lake immediately after the quake, breaking into smaller icebergs and causing 3.5 meter-high (11-foot) waves.

“It was approximately 30 million tons of ice, it’s just a massive, massive, massive scale,” said Denis Callesen, the General Manager of Tourism at Aoraki Mount Cook Alpine Village.