Severe Tropical Cyclone Pam Makes Landfall on Vanuatu: AIR Report

A report from catastrophe modeling firm AIR Worldwide describes the movement of Tropical Cyclone Pam over the last two days. The storm in the South Pacific has intensified rapidly, and is now a Category 5 storm (on the BOM scale) – “one of the strongest tropical cyclones ever recorded in the area.”

AIR said the “eye of the storm will pass very close, or perhaps directly over, all six of the southernmost populated islands of Vanuatu today: Efate (including the capital of Port Vila), Erromango, Aniwa, Tanna, Futuna, and Aneityum. The islands will likely experience extreme devastation and perhaps the greatest disaster in their recorded history.

“The Republic of Vanuatu is a 1,300 km (810 miles) long archipelago about 1,200 miles northeast of Brisbane, Australia. It consists of about 82 small islands, of which 65 are inhabited. Vanuatu’s total land area is 12,190 square kilometers, and it has a population of more than 245,000.

“Given its location in the South Pacific, Vanuatu is prone to natural hazards, particularly earthquakes and tropical cyclones. A recent study AIR performed under the auspices of the World Bank and Asia Development Bank found that Vanuatu is expected to incur, on average, $48 million per year in losses due to these hazards.”

Dr. Richard Yablonsky, scientist at AIR Worldwide, commented: “Leading up to this morning, Eastern Time, Pam was a large, well-organized, and extremely powerful tropical cyclone with a distinct eye, coherent eyewall, and nearly symmetric structure. As Pam was approaching the southern islands of Vanuatu, it began moving over cooler water, which made Pam’s maximum intensity unsustainable.”

“This morning, Eastern Time, Pam’s track close to the eastern edge of the island of Efate means that Port Vila is about to enter the western eyewall, with strong winds. Storm surge in Port Vila could also be high, even though it is on the ‘back side’ of the circulation with limited fetch, because the water could pile up in Mele Bay as the center of Pam passes by to the east. Similar, but perhaps more extreme circumstances created the storm surge in Lake Pontchartrain on the ‘back side’ of Hurricane Katrina in 2005, which ultimately broke through the levees and flooded New Orleans.”

Fiji, just over 650 miles east of Port Vila, may also be impacted by bands of heavy rain, dangerous waves, and storm surge.

“Primary impacts from Pam in southern Vanuatu will be the damaging winds, flash flooding inland from rainfall, and major damage from storm surge early Saturday morning local time,” Dr. Yablonsky continued. “Pam’s impacts could exceed severe tropical cyclones Uma (1987) and Ivy (2004), as well as the unnamed tropical cyclone in 1951, which killed around 100 people and may be considered Vanuatu’s worst natural disaster to date.”

By AIR’s estimations “approximately half of the total building exposure consists of single-story timber frames and traditional buildings, one third are single-story masonry/reinforced concrete buildings and about 7 percent are categorized as uninhabitable or of poor construction. With respect to occupancy type, about 90 percent of the entire exposure is residential and only 3 percent of the buildings are public, the rest being categorized as commercial, industrial, etc.

“Timber and traditional buildings are highly vulnerable to wind damage and could experience significant damage during a large intensity event. The balance of Vanuatu’s building stock comprises primarily masonry and reinforced concrete buildings, which typically experience much less damage during tropical cyclones as they are much more resilient to wind damage.”

AIR said that it “estimates that the replacement value of all the assets in Vanuatu is $3.3 billion, about 86.5 percent of which represents buildings and 12.5 percent of which represents infrastructure assets, including major ports, airports, power plants, bridges, and roads.

“The province with the highest building replacement cost density is Shefa, which also includes the nation’s capital city Port Vila, where more than 10 percent of the nation’s population is concentrated. The islands are mountainous and forested, and less than 10 percent of the land is available for agriculture. Nevertheless, more than 78,000 hectares are used for major crops, such as coconut, palm oil, taro, and vanilla.”

Dr. Yablonsky concluded: “Even if Pam does not make landfall, it will pass close enough to the islands for its hurricane force winds, which extend 40 miles from the center, to cause serious damage. After passing Vanuatu, Pam should weaken significantly, but it could bring at least tropical storm force winds and high surf to New Zealand on Sunday.”

Source: AIR Worldwide