Natural Hazards

Tsunami

Tsunami Risk in Taranaki

New Zealand’s coastline is exposed to tsunami risk due to its location on the edge of the Pacific Ocean and surrounding seas. A tsunami is a temporary change in sea level caused by undersea earthquakes, landslides, or volcanic eruptions, resulting in a series of waves and unusual coastal currents. These waves can travel quickly and cause serious flooding and damage when they reach land.

Who is most at risk?

• Communities close to the coast are most at risk, especially those in low-lying areas.
• Areas close to where rivers and streams meet the sea can also be more vulnerable, as tsunami waves can travel inland along these waterways.
• People in beach settlements and coastal towns should be especially aware of evacuation routes and warning systems.

Evacuation maps are available for the Taranaki region to help people understand which areas may need to evacuate in a tsunami. As these maps have been created using relatively coarse seafloor and land mapping data, they should be used to indicate areas of risk across Taranaki. They are not suitable for providing a detailed property-level understanding of risk.

These maps are included in the following reports and are also available on the Taranaki Emergency Management website here.

Earthquake

Earthquake Risk in Taranaki

New Zealand is situated on the boundary of two active tectonic plates, and as a result experiences many earthquakes which can happen anywhere, including in Taranaki. Earthquakes are caused by sudden movements in the earth’s crust and can lead to strong ground shaking, damage to buildings and infrastructure, and in some cases, tsunami, landslides or liquefaction.

Who is most at risk?

• All parts of Taranaki are exposed to earthquake risk, but areas near known faults may experience stronger shaking.
• Soft soil areas, such as river valleys and reclaimed land, are more likely to experience amplified shaking, liquefaction and suffer damage.
• Coastal communities may also be at risk from tsunami waves if an offshore fault ruptures.
• Infrastructure near fault zones, such as roads, rail lines, and pipelines, may be vulnerable to ground movement or liquefaction.
• Landslides may be triggered on steep land.

Ground shaking hazard maps are available for some identified faults in the Taranaki region. These maps help highlight areas where earthquake shaking may be stronger or where the ground may respond unpredictably, such as amplifying the shaking or being prone to liquefaction. However, because these maps are based on broad geological data, they are best used to understand general patterns of risk across the region. They are not suitable for providing a detailed property-level understanding of risk.

Some of these maps are included in the technical reports below. There are also maps for known active faults available through the GNS Active Faults Database, which can be accessed online here. It is important to note that not all known faults are shown on these maps, and there may be additional faults that have not yet been identified through geological investigations.

Volcanic

Volcanic Risk in Taranaki

Taranaki Maunga is an active volcano with a long history of eruptions. The last known eruption occurred in 1790, and scientists estimate there is a 30-50% chance of another eruption in some form within the next 50 years. Volcanic activity can occur with little warning and may affect communities across the region.

Volcanic eruptions are highly variable and produce many hazard risks. Volcanic risks close to the vent include thrown rocks, hot and toxic gasses and lava. Further from the vent risks include large hot ash and gas flows (pyroclastic density currents), ash that accumulates on the ground and covers all surfaces, and ash that is washed down rivers during rain events as mudflows (lahars). Ashfall may extend hundreds of kilometres downwind, with heavy ash falling closer to the vent and gradually becoming finer. Debris avalanches are very rare – at least 14 in the last 200,000 years – but may occur where parts of volcano fall off, and in the largest of events may extend as far as the Taranaki coastline.

Eruptions at Taranaki tend to happen in cycles. The Maunga will be active for a period, followed by a quiet phase with no volcanic activity. We are currently in one of these quiet periods. Looking at past evidence, Taranaki has experienced both short and long quiet phases. Scientists cannot yet tell whether the current quiet period is short or long.

The longer the quiet period continues, the more likely it is that we are in a long quiet phase. This means the likelihood of an eruption may be decreasing over time.

Who is most at risk?

• Communities near the mountain are most at risk from hazards like lahars (volcanic mudflows), pyroclastic flows, and ash fall.
• Coastal towns and river valleys may be affected by lahars, which can travel quickly down waterways.
• Infrastructure such as roads, bridges, power lines, and water supplies may be damaged by ash, debris, or flooding.
• Farms and livestock may be impacted by ash fall, which can contaminate water and make pasture inedible.

Evacuation zones and volcanic hazard maps have been developed to help guide emergency planning and land use decisions. These maps are available in the Mt Taranaki Volcanic Unrest Response Plan below. As these maps have been created using historic geologic data, they should be used to indicate areas of risk across Taranaki. They are not suitable for providing a detailed property-level understanding of volcanic risk.

Coastal Hazards

Coastal Hazards in Taranaki

Taranaki’s coastline is exposed to a range of coastal hazards, particularly erosion and the long-term effects of sea-level rise. These hazards can damage property, infrastructure, and natural environments, and may worsen over time due to climate change.

Coastal erosion in Taranaki is driven by wave action, storm surge, sediment loss, and human activities such as dune flattening and vegetation removal.

Sea-level rise is expected to increase the risk of coastal erosion and flooding, especially in low-lying areas.

Who is most at risk?

• Beachfront properties and low-lying coastal areas are most exposed to erosion and flooding.
• Cliffed coastlines, such as those at Onaero and Bell Block, are vulnerable to collapse and retreat.
• Areas with historical shingle extraction or poorly designed seawalls may experience accelerated erosion.
• Communities near river mouths may face increased erosion and flooding as sea levels rise.

Climate change will likely lead to more frequent and severe coastal inundation events.

National sea level rise hazard maps are available on the NIWA Coastal Flood Layers Viewer here and Aotearoa’s coastal change dataset is available on the Coastal Change website here. These maps are valuable for regional planning and general hazard awareness, but they are not suitable for assessing risk at the individual property level.

Wind and Tornado

Wind and Tornado Hazards in Taranaki

Taranaki is exposed to strong winds and occasional tornadoes due to its location and terrain. Taranaki Maunga plays a major role in shaping local wind patterns, creating orographic winds, airflows that are influenced by the mountain’s shape and elevation. These winds can be especially strong at higher altitudes but also affect surrounding lowland areas.

Wind Hazards

• Gale force winds are common across the region.
• Cyclones and thunderstorms can bring short bursts of extremely strong winds.

Tornado Hazards

• Taranaki experiences about one tornado per year, with more severe events occurring every few years.
• Tornadoes can cause damage to homes, vehicles, and vegetation, and may be accompanied by heavy rain, hail, and lightning.

Who is most at risk?

• Exposed coastal and inland areas, especially near the mountain, are more likely to experience strong gusts.
• Most tornadoes occur in the New Plymouth District, often forming offshore as waterspouts and moving inland.
• New Plymouth experiences more thunderstorm days per year than other parts of the region.
• New Plymouth, Bell Block, Inglewood, and Waitara have all recorded damaging wind and tornado events.
• While the New Plymouth district is most at risk, damaging wind events can also occur in other areas across the region.
• Infrastructure, such as power lines, buildings, and trees, are all vulnerable to wind damage.

Climate change may increase the frequency and intensity of extreme wind events.

Historical reports are available for the region below and provide useful insights into where damage has occurred in the past. These reports can help identify areas that may be more exposed to wind and tornado hazards. However, due to the unpredictable and localised nature of tornadoes and the far-reaching impacts of storms, these reports should not be used to assess risk at the individual property level.

Landslide

Landslide Hazards in Taranaki

Landslides occur when soil, rock, or debris moves down a slope, often triggered by heavy or prolonged rainfall, earthquakes, or human activity. In Taranaki, landslides are a natural hazard due to the region’s steep terrain, volcanic soils, and high rainfall.

Landslide risk increases after long periods of rain or during intense storms. Earthquakes can also trigger landslides, especially in areas with saturated soils. Climate change may increase the frequency of heavy rainfall events, raising the likelihood of future landslides.

Who is most at risk?

• Properties located on or below steep slopes, especially in hill country and near riverbanks.
• Areas with unstable or easily erodible soils, such as volcanic ash or weathered rock, are more prone to movement.
• Roads, rail lines, and pipelines that cross steep terrain may be vulnerable to disruption.
• Landslides can also occur in urban areas where vegetation has been removed or drainage is poor.

The presence of historical landslides can be used to indicate areas that are prone to landslide risk. Where historical landslides have been identified they are available on the Geological and Nuclear Science website here. These maps are not suitable for providing a detailed property-level understanding of risk

Drought

Drought Hazards in Taranaki

Droughts occur when there is a prolonged period of below-average rainfall, often accompanied by elevated temperatures, leading to water shortages and intensified dry conditions. Taranaki is vulnerable to drought, particularly during El Niño weather patterns, which can reduce rainfall across the region.

Droughts can affect crop yields, livestock health, and water availability for households and businesses. They may also increase the risk of wildfires and reduce stream flows, impacting ecosystems and water quality.

Who is most at risk?

• Farmers and rural communities that rely on rainfall for pasture growth and water supply.
• Areas with limited access to groundwater or stored water may experience shortages more quickly.
• Urban areas may face water restrictions during extended dry periods.

Climate change is expected to increase the frequency and severity of droughts in New Zealand, including in Taranaki.