Earthquake Risk Assessment 1995 Wellington
Search in document libraryPurpose of the report to assess the potential impact of earthquakes on buildings, infrastructure, and population in Wellington City.
Geographic Area Covered
The report covers Study Area 1, Wellington City, including Miramar Peninsula, Rongotai, Kilbirnie, Lyall Bay, Newtown, Hataitai, Te Aro, Thorndon, Karori, Ngaio, Khandallah, Johnsonville, and Newlands.
Summary of the Report
This report evaluates the potential risks and impacts of earthquakes on Wellington City’s buildings, critical facilities, and population. It forms part of a broader strategy by the Wellington Regional Council to manage geological hazards. The study uses two earthquake scenarios: Scenario 1 involves a large distant earthquake with moderate shaking, while Scenario 2 considers a severe local earthquake on the Wellington Fault. The assessment includes ground shaking, liquefaction, slope failure, and fault rupture hazards.
The study area includes a mix of residential, commercial, and industrial zones. Building vulnerability varies based on construction type, age, and ground conditions. Residential buildings, mostly timber-framed, show lower vulnerability compared to commercial and industrial buildings, which include older and more varied construction types. Buildings on soft or reclaimed land are more susceptible to damage due to amplified shaking and liquefaction.
Estimated repair costs for Scenario 1 are $178 million in 1995 dollars, which equates to approximately $322 million in 2025. Scenario 2 estimates reach $2.25 billion in 1995 dollars, or approximately $4.08 billion in 2025. Residential damage costs are lower than commercial/industrial due to construction type and location. Casualty estimates for Scenario 1 include 11 fatalities and 168 injuries during daytime, while Scenario 2 could result in 346 fatalities and 2,850 injuries. Nighttime casualties are significantly lower due to occupancy patterns.
Critical facilities such as hospitals, police stations, and fire stations were assessed for damage probabilities. Some facilities show moderate to extensive risk, especially older buildings not upgraded to modern standards. Fire following earthquake is identified as a secondary hazard, particularly in densely built areas with limited access and flammable materials.
The following table lists the estimated probabilities of critical facilities in Wellington being in each damage state under Scenario 2. These estimates are based on the original earthquake risk assessment report and reflect the likelihood of structural damage ranging from none to complete.
Estimated Damage to Critical Facilities in Wellington City (Scenario 2)
|
Facility |
None |
Light |
Moderate |
Extensive |
Complete |
|
Wellington Central Police Station |
18% |
61% |
25.7% |
10% |
0% |
|
Wellington Hospital |
0–10% |
55% |
20–35% |
10–45% |
0% |
|
Wellington Ambulance |
10% |
61% |
18.7% |
8% |
0% |
|
Wellington City Civil Defence HQ |
0% |
55% |
16% |
10% |
18% |
|
Brooklyn Fire Station |
46% |
59.2% |
3% |
0% |
0% |
|
Kilbirnie Fire Station |
20–35% |
18.7% |
17% |
5% |
0% |
|
Newtown Fire Station |
0% |
44% |
11.6% |
5% |
0% |
|
Thorndon Fire Station |
10–45% |
61% |
34.1% |
8% |
0% |
|
Johnsonville Fire Station |
0% |
55% |
16% |
10% |
18% |
|
Khandallah Fire Station |
0–25% |
59.2% |
3% |
0% |
0% |
|
Newlands Fire Station |
20% |
35% |
10% |
5% |
0% |
|
Northland Fire Station |
0% |
44% |
11.6% |
5% |
0% |
The report concludes that Wellington City faces substantial risk from a severe local earthquake, especially in areas with soft soils and older buildings. Strategic planning, emergency preparedness, and infrastructure resilience are essential to mitigate potential impacts.