The magnitude 7.0 earthquake which struck the Southern Island of New Zealand on Saturday, Sept. 4 miraculously caused no fatalities; however it did cause substantial damages. Catastrophe modeling firm AIR Worldwide has estimated that industry insured losses from quake will be between NZD 2.700 billion (US$2.0 billion) and NZD 6.0 billion (US$4.5 billion).
AIR indicated that “a more complete picture is emerging of the impacts of Saturday’s M7.0 earthquake that struck near Christchurch on New Zealand’s South Island. Damage in this city of about 350,000 is widespread, but generally moderate in severity. Unfortunately, gale force winds, which are forecast for Sunday, could pose additional stress on already weakened buildings. Aftershocks, too, are a concern; at least three have been of magnitude 5 or greater.”
The huge difference in loss of life between the earthquake that struck Haiti in January, the earthquake in Chile at the end of February, and the New Zealand quake underscores the importance of strict building codes and their enforcement. According to AIR, “while design requirements for new construction in New Zealand are quite stringent, Christchurch—the country’s oldest city—has many historical masonry buildings, which dominate the central business district. Few had undergone seismic retrofit and many were the target of strong ground motion caused by the earthquake, which is now estimated to have occurred at a depth of just 5 km [app. 3.1 miles and about 44 km [27.5 miles] from the city. The shallow focal depth will undoubtedly have exacerbated the damage.
“Christchurch’s central business district was heavily affected. Streets lined with buildings of unreinforced masonry or frame with masonry infill walls are now littered with fallen bricks and broken glass. Whole sections of walls fell away from buildings’ frames, and chimneys and parapets toppled. Officials in Christchurch have activated the Building Safety Evaluation process, roping off streets so buildings can be individually assessed. It is likely that many older masonry buildings—even those in which damage is not immediately apparent—will have sustained cracks that compromise structural integrity. Broken shop windows led to some looting and an overnight curfew was imposed, though it was said to be intended to protect people from falling debris.
“Significant damage to residential structures has also been reported, including some collapses in inland Canterbury nearer the epicenter. Much of the damage seems to have been the result of toppled chimneys smashing roofs and the contents beneath.”
According to AIR, Saturday’s earthquake is thought to have occurred on the “Porters Pass-Amberley Fault Zone (PPAFZ), which forms the southern part of the collision zone along the Pacific-Australia plate boundary. Scientists at New Zealand’s Institute of Geological and Nuclear Sciences (GNS Science), however, are now speculating that it occurred on a previously unknown fault. GNS Science is joining forces with several local and regional universities to deploy 40 portable instruments in the epicentral region that will record aftershocks; data will be used to better understand the rupture mechanism of the main shock and to ascertain whether seismic stress may have been transferred to neighboring faults.”
AIR added that its loss estimates are based on “insured physical damage to property (residential, commercial/ industrial), both structures and their contents and direct business interruption losses. They do not reflect losses to uninsured properties, losses to land, losses to automobiles, losses to infrastructure, indirect business interruption losses, loss adjustment expenses and losses from non-modeled perils, including fire-following and landslide.
In addition AIR explained that its estimates do not take into account “demand surge—the increase in costs of materials, services, and labor due to increased demand following a catastrophic event. Demand surge can be applied by AIR software users who want to account for this variable.”
Source: AIR Worldwide
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