The glacier is 200km (125 miles) away from Christchurch, near the west coast of the South Island, in Aoraki/Mount Cook National Park.
The ice was dislodged on Tuesday afternoon, just after the earthquake struck. The piece of ice was 1.2km (0.75 mile) long, 300m (330 yards) high and 75m (80 yards) wide. (Right: ice sheet with iceberg out to right of it)
The ice has broken up into icebergs now floating in the Tasman Lake, one of which is 250m long.
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. A group of tourists were on a boat in the lake at the time and were thumped by giant waves caused by the ice drop. The tourists were not in danger and were not injured.
"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. (Right: iceberg in Tasman Lake after quake)
He added the ice fall or 'calving' was expected, given the large amount of recent rain, the changing of the dynamics of the lake and the La Nina weather phenomenon, a factor in higher levels of rainfall.
"We have known for some weeks that an event was coming, what is just a complete curve ball, left field, is that it was the earthquake that set it off and caused the calving," Callesen stated. (Left: Tasman Lake)
Callesen added that icebergs now cover a quarter of the five km by two km Tasman Lake, which is about 200 km west of Christchurch on New Zealand's South Island.
Reuters,"NZ quake sends 30 million tons of ice loose from glacier",by Amy Pyett, accessed February 23, 2011
TNT Magazine, "Christchurch earthquake causes ice to fall off Tasman Glacier", accessed February 23, 2011