New Zealand

	Earthquake

New Zealand Earthquake

New Zealand is situated in the South Pacific Ocean at the intersection of the Pacific and Indian tectonic plates. The convergence of these crustal masses has raised and split New Zealand, shaping the landmass into two separate islands. Active volcanoes and frequent earthquakes are constant reminders of the impact of the Earth’s forces on New Zealand.

The country’s tectonic diversity results in numerous earthquakes, shallow and deep, on land and offshore. On average, New Zealand experiences one magnitude (M) 6 earthquake per year, one M7 or greater earthquake per decade, and one M8 or greater earthquake per century.

Major events that occurred in New Zealand over the last century include the 1931 Hawke’s Bay and 1929 Murchison earthquakes. The Murchison Earthquake triggered numerous landslides, and the Hawke’s Bay event spawned fires that caused massive damage as they swept through Napier.

The Wellington region is particularly vulnerable to earthquakes due to poor soil quality and high concentrations of exposure. The worst earthquake to occur in the Wellington area was the 1885 rupture of the Wairarapa Fault. This M8.3 event resulted in 12.2 meters (40 feet) of horizontal displacement and 2.7 meters (9 feet) of vertical displacement along the fault, which drained swamps at the mouth of the Hutt Valley. A repeat of this event is considered to be one of the worst-case scenarios for the Wellington region.

Since 1996, the RMS® New Zealand Earthquake Model has been utilized by insurers, reinsurers, and capital markets constituents to evaluate and transfer earthquake risk in New Zealand. In 2007, a full model upgrade was performed to incorporate the latest advances in earthquake methodologies.

Model Highlights

	Model developed in consultation with New Zealand’s Institute of Geological and Nuclear Sciences (GNS) and National Institute of Water and Atmospheric Research (NIWA)
	Stochastic database of earthquake events including over 16,000 simulated earthquakes; source model includes 346 mapped faults; incorporates magnitude uncertainty and time-dependence
	High-resolution hazard modeling using the RMS variable resolution grid (VRG); includes databases for soil type and liquefaction susceptibility
	RMS third-generation earthquake modeling incorporating spectral response approach to building damage calculations
	Vulnerability functions capture the unique behaviour of the New Zealand building stock including regional variations with building inventory data in case of unknown primary characteristics
	Broad suite of secondary modifiers to help refine building damage assessment
	Analysis output at the 2006 postcode vintage
	Secondary perils: Fire Following Earthquake (FFEQ), tsunami accumulation footprints

Geographic Scope

All of New Zealand

Exposure Data Resolution

Data input supported at the following levels of resolution: coordinate, postcode, city, territorial local authority (TLA, county equivalent), and CRESTA zone

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