Ice calving, also known as glacier calving or iceberg calving, is the breaking off of chunks of ice at the edge of a glacier. It is a form of ice ablation or ice disruption. It is the sudden release and breaking away of a mass of ice from a glacier, iceberg, ice front, ice shelf, or crevasse. The ice that breaks away can be classified as an iceberg, but may also be a growler, bergy bit, or a crevasse wall breakaway.
Calving of glaciers is often preceded by a loud cracking or booming sound before blocks of ice up to 60m (200') high break loose and crash into the water. The entry of the ice into the water causes large, and often hazardous waves. The waves formed in locations like Johns Hopkins Glacier can be so large that boats cannot approach closer than 3km (2 miles). These events have become major tourist attractions in locations such as Alaska.
Many glaciers terminate at oceans or freshwater lakes which results naturally with the calving of large numbers of icebergs. Calving of Greenland's glaciers produce 12,000 to 15,000 icebergs each year alone.
Calving of ice shelves is usually preceded by a rift. These events are not often observed.
Etymologically, calving is cognatic with calving as in birthing a calf.
Hubbard Glacier is a glacier located in eastern Alaska and part of Canada.
The longest source for Hubbard Glacier originates 122 kilometres (76 mi) from its snout and is located at about at about 61°00′N140°09′W / 61.000°N 140.150°W / 61.000; -140.150, approximately 8 kilometres (5 mi) west of Mount Walsh with an altitude around 11,000 feet (3,400 m). A shorter tributary glacier begins at the easternmost summit on the Mount Logan ridge at about 18,300 feet (5,600 m) at about 60°35′0″N140°22′40″W / 60.58333°N 140.37778°W / 60.58333; -140.37778.
Before it reaches the sea, Hubbard is joined by the Valerie Glacier to the west, which, through forward surges of its own ice, has contributed to the advance of the ice flow that experts believe will eventually dam the Russell Fiord from Disenchantment Bay waters.