Hawke's Bay is one of New Zealand's most seismically active regions. Several large and damaging earthquakes have been recorded in the last 160 years. Most notably, the 1931 earthquake claimed many lives, reshaped the region's landscape, transformed our cities and towns and left an indelible scar on the community's living memory.
Every year, Hawke's Bay experiences many smaller earthquakes. Another large earthquake could occur at any time.
New Zealand lies along the boundary of the Australian and Pacific Plates. In the North Island, these two plates meet in a subduction zone, where the Pacific Plate plunges beneath the Australian Plate.
The plates don't move past each other easily and stresses build up, causing earthquakes when faults suddenly rupture to relieve the built-up pressure. Some faults are deep beneath the earth's surface while others are visible as surface fault lines. The magnitude of an earthquake depends on the size and nature of the fault that ruptures and the amount of slip that occurs. The plates are constantly moving and earthquakes occur all the time, although most are too small to be felt by people. Sometimes, however, a large fault rupture produces a big earthquake. Large earthquakes can be very damaging to life and property and constitute a major hazard to people living in earthquake-prone areas.
Hawke's Bay's Tectonic Setting
Hawke's Bay is located on the Australian Plate, about 150km west of the Hikurangi Trough, which marks the subduction boundary between the Pacific and Australian Plates. At this latitude, the two plates are converging obliquely at about 42mm/yr. The interface between the two plates is a large fault that dips about 6° to the west near the Hikurangi Trough and steepens to about 25° below Hawke's Bay.
Hawke's Bay's location above the subduction interface means it is within a zone of high deformation and consequently many earthquakes.
Previous Impacts in Hawke's Bay
Most of Hawke's Bay's moderate to large earthquakes have been on shallow faults, less than 45km deep. However, a few, such as the June 1921 Hawke's Bay earthquake, were caused by rupture at greater depths.
What to do?
Most people in Hawke's Bay will survive a large earthquake with little loss, but some will be severely affected. Actions you take now can significantly reduce damage to your home and business and help you survive.
Before an earthquake
- Develop a Household Emergency Plan and prepare an Emergency Survival Kit so you can cope with being on your own for three or more days.
- Identify safe places in your home, school or workplace. A safe place is:
- under a strong table; remember to hold onto the table legs
- next to an interior wall close by.
- A safe place should be no more than a few steps or two metres away to avoid injury from flying debris - so identify a place in each room of your home.
- Secure heavy items of furniture to the floor or wall. Visit www.eq-iq.org.nz to find out how to 'quake safe' your home.
- Seek qualified advice to ensure your house is secured to its foundations. Also check that renovations comply with the New Zealand Building Code.
During an earthquake
Falling objects and collapsing structures cause injuries and deaths during earthquakes. Knowing how to protect yourself when the shaking starts may save your life.
- If you are inside a building, move to a safe place. Drop to the floor and shelter under a strong table or desk. Cover your head and face to protect them from broken glass and falling objects. Hold onto the table or desk and be prepared to move with it. Hold your position until the shaking stops. This is called the 'DROP, COVER and HOLD' procedure.
- DO NOT run outside during the shaking or use the stairways or lifts. Many people are killed just outside buildings by collapsing walls, falling bricks and other debris.
- If you are outside, get into the open away from buildings, streetlights and power lines. The greatest danger exists directly outside buildings, at exits, and alongside exterior walls. Ground movement during an earthquake is seldom the direct cause of death or injury. Most earthquake-related casualties result from collapsing walls, flying glass and falling objects.
- If you are driving, pull over and stop. If safety permits, avoid stopping near or under buildings, trees, overpasses and utility wires. Stay in your car and wait for the shaking to stop.
- If you are at the beach or near the coast, move to higher ground as soon as the shaking stops in case tsunami follows the 'quake.
After an earthquake
- Expect to feel aftershocks, some of which may be very strong.
- Help those around you if you can.
- If you are in a damaged building, try to get outside and find a safe, open place after the shaking stops.
- If you are trapped under debris, don't light a match, move about or kick up dust. Cover your mouth with a handkerchief or clothing. Tap on a pipe or wall so rescuers can locate you. Shout only as a last resort. Shouting can cause you to inhale dangerous amounts of dust.
- Extinguish any fires and wood burners or open fires immediately.
- Inspect utilities.
- Check for gas leaks. If you smell gas, open windows and quickly leave the building. Turn off the gas at the outside main valve if you can do so safely and call the gas company from a neighbour's home. If you turn off the gas for any reason, a professional must turn it back on.
- Look for electrical system damage. If you see sparks or evidence of electrical system damage, turn off the electricity at the main fuse box if it is safe to do so. If you have to step in water to get to the fuse box, call an electrician for advice first.
- Check for sewage and water lines damage. If you suspect sewage lines are damaged, avoid using the toilets and call a plumber. If water pipes are damaged, contact the Council and avoid using water from the tap.
- Listen to the radio for information and advice. If power is off and you don't have a battery-operated radio, you could use a vehicle radio
- If your property is damaged, take notes and photographs for insurance purposes.
For more information on earthquakes and earthquake preparedness go to: