ICEBERG FLIPPED OVER, large section of ice that has broken off an ice shelf or glacier and drifted into the open ocean and tipped onto its underside. To be classified as an iceberg, the mass must protrude at least sixteen feet above sea level and cover an area of at least 5,382 square feet.
Icebergs are known for concealing around ninety percent of their bulk underwater. It is rare for icebergs to flip over because their roughly pyramidal shape gives them a great deal of stability. When an iceberg flips, it does so most often right at the moment of its birth, when it breaks off from the edge of a glacier (a process called “calving”) and drops into the ocean. Melting can also gradually imbalance an iceberg by redistributing its salt content, causing it to eventually split or flip over. Climate change is believed to be increasing the number of iceberg flips.
While the tip of an iceberg collects snow and dirt, its underside is smooth and glassy with a striking blue-green color and visible veins of water running through it. The color is due to the high density of the ice—the immense weight of an iceberg compresses the ice at the bottom, squeezing out air bubbles and packing it more densely.
The frequency of iceberg flips is difficult to record owing to the remoteness of the locations in which they occur. Icebergs can weigh hundreds of millions of tons, and a large iceberg flip will create enormous waves. Iceberg flips can be partially deduced from seismographic readings but need to be visually confirmed to distinguish them from other seismic events.