When a hurricane strikes land, the storm surge can be more deadly than the storm’s violent wind. Tropical cyclones – called hurricanes in the Atlantic, typhoons in the Pacific, and cyclones in Australia and India – have killed over 1 million people in the past hundred years. The majority of those deaths are attributed to the surge component of the storm.
Typhoon Haiyan hit the Philippine Islands city of Tacloban on November 11, 2013, with a wind speed of 195 mph (315 km/h), the strongest landfall speed ever recorded. Over 5,000 died and the city was leveled. The savage wind took its toll, but it was the 20 ft. (6.6m) wall of ocean water surging more than a mile (1.6 km) inland that took most of the lives.
When Superstorm Sandy came ashore in New Jersey and New York in late October, 2012, the wind speed was only 115 mph (185 km/h), but the storm was so massive it pushed a 14 ft. (4.4m) storm surge far inland, killing more than 100 and wiping out or badly damaging thousands of homes. Reconstruction costs have reached $70 billion.
In August, 2005, Hurricane Katrina, a Category 3 with a wind speed of120 mph (192 km/h) struck New Orleans and Gulf Coast cities in Louisiana, Mississippi, and Alabama. Although the wind did some damage, the storm surge with waves as high as 28 ft. (7.5m) wiped out shoreline communities, and breached New Orleans’ levees, flooding the city, and causing most of the 1,800 deaths.
Some of the most destructive storm surges have occurred in Bangladesh and India. The northern end of the Bay of Bengal is funnel shaped, and storm surges become tidal bores that sweep many miles inland. The Bhola cyclone in 1970 produced a storm surge of 35 ft. (11m), taking 500,000 lives in Bangladesh. The largest storm surges ever recorded took place in India in 1839 when a 40 ft. (12.2m) surge killed 300,000; and in Bathurst Bay, Queensland, Australia, where a 42 ft (12.8m) surge killed 400 in 1899. It was reported at the time that dolphins and fish were found atop the cliffs surrounding the bay.
A storm surge is created by the storm’s high wind piling the ocean’s surface higher than ordinary sea level. Low pressure at the center of the weather system has a lifting effect and aids in the buildup of the sea and the energy of the surge.
People living near the shoreline in tropical storm-prone areas should be prepared not only to protect property against the high wind, but also be aware of storm surge danger, and prepared to evacuate before the storm makes landfall.