Wanganui District Council Wanganui spreads along the lower reaches of the Whanganui River

Earthquakes

Hundreds of earthquakes occur in New Zealand each year. Many of them are so deep that only a few cause damage and injury. However, a severe earthquake could occur at any time. Photo: Inside a Whakatane supermarket after the 1987 Edgecumbe earthquake

Wanganui Earthquake History

Earthquake risk
Information on Wanganui's earthquake risk is available on this page (PDF, 83KB). It includes details of earthquake faults that may affect Wanganui, what you can expect to happen in the event of a large earthquake and what you should do if one occurs.

Earthquake-prone buildings
Wanganui District Council has prepared information to assist owners of potentially earthquake-prone buildings. You can read the information on this page (PDF, 49KB). The Council's Earthquake-Prone Buildings Policy is available here (PDF, 35KB).

What you can do to help yourself

Before an earthquake occurs:

  • Secure heavy furniture to the wall or floor.
  • Place heavy items on bottom shelves or on the floor.
  • Put strong catches on cupboards.
  • Check your chimney is secure.
  • Secure your hot water cylinder and header tank (if you have one).
  • Check that your household insurance covers earthquake damage.
  • Assemble your survival kit items and ensure everyone in your household knows where your kit is kept.
  • Join a Neighbourhood Support Group. Contact the Neighbourhood Support office on phone 348 0568 for more details. Your best help will be a friendly neighbour.

During an earthquake, if you are inside:

Drop Cover Hold

  • Stay inside. Take cover in the strongest part of the house away from windows.
  • Stay by an inside wall or in the smallest room.
  • If you are in bed, roll onto the floor away from any windows.
    Don't
    get under the bed. Stay close beside the bed, rolled up in your blankets/quilt.
  • If you are in a lift, stop it at the nearest floor and get out.

During an earthquake, if you are outside:

  • Stay outside. Move away from buildings, trees, streetlights and power lines.
  • Crouch down and cover your head.
  • Beware of flying glass or falling objects.
  • If you are driving, pull over and stop. Keep your seatbelt on and stay in the vehicle - it will provide some cover.

After an earthquake:

  • Listen to your radio for advice on what to do.
  • Put on strong footwear.
  • Check those around you and help them if necessary.
  • Make sure someone contacts help if there are medical needs.
  • The message that people in your area are all right is also important to Civil Defence.
  • Evacuate your building only if it is unsafe, but stay close by if you can until everyone is accounted for.
  • After a big earthquake expect aftershocks.
  • Don't go sightseeing - you'll hamper relief efforts.
  • Put out small fires and eliminate fire hazards.

More information on what to do after an earthquake (PDF, 144KB)

Safe places in an earthquake

Somewhere close to you, no more than a few steps or less than three metres away, to avoid injury from flying debris.

Under a strong table. Hold on to the table legs to keep it from moving away from you.

Next to an interior wall, away from windows that can shatter and cause injury and tall furniture that can fall on you. Protect your head and neck with your arms.

Keep in mind that in modern homes, doorways are no stronger than any other part of the structure and usually have doors that can swing and injure you.

 

Significant earthquakes for Wanganui

Date

Magnitude

Epicentre

Effect in Wanganui

1843

7.5

Wanganui

Extensive lateral spreading of the terrace margin to the Whanganui River. Putiki church demolished.

1848

7.1

Marlborough

Minor lateral spreading in the riverbed. Some wharf damage. The western bank of the Whanganui River (Taupo Quay) rose by one metre.

1855

8.2

Wairarapa

Extensive lateral spreading and fissuring of lower terrace along the Whanganui River, especially Taupo Quay. Extensive wharf damage. Most chimneys destroyed. Much broken crockery inside houses. Putiki's new brick church destroyed. The shock cracked the iron pan under the swamps of Gonville, allowing the water to drain completely away.

1868

7 - 7.5

Cape Turnagain

On October 19 there was a large shallow earthquake, magnitude 7.0-7.5, off Cape Turnagain; changes in river levels were reported at Wanganui and Waitara. These were possibly caused by a tsunami, but may have been the result of seiching (earthquake-generated waves).

1897

?

Waverley area

Loss of water supply. Subsidence/lateral spreading. Damage to wharves. Loss of chimneys in some areas. Minor ground cracking in Glasgow Street.

1934

7.6

Pahiatua

Extensive chimney damage in some areas. Two slips and fissuring of the riverbank at Aramoho. Break in water pipes at the foot of St John's Hill. Rutland Hotel damaged.

1991

6.5

Off Bulls coast

1000 chimneys damaged. 2140 claims to the Earthquake Commission.

What to tell children about earthquakes

  • Find safe places in every room of your home and classroom. Look for safe places inside and outside of other buildings where you spend time. The shorter the distance you have to travel when the ground shakes, the safer you will be.
  • If you are indoors during an earthquake, drop, cover and hold on. Get under a desk, table or chair. Hold onto the legs and cover your eyes (broken glass). If there's no table or desk nearby, sit down against an interior wall. An interior wall is less likely to collapse. Pick a safe place where things will not fall on you, away from windows, bookcases or tall, heavy furniture. It is dangerous to run outside when an earthquake happens. Bricks, roofing and other material may fall during and immediately after earthquakes, injuring people near the building.
  • Wait in your safe place until the shaking stops, then check to see if you are hurt. You will be better able to help others if you take care of yourself first, then check the people around you. Move carefully and watch out for things that have fallen or broken, creating hazards. Be ready for additional earthquakes called 'aftershocks'.
  • If you must leave a building after the shaking stops, use the stairs, not the lift. Earthquakes can cause fire alarms and fire sprinklers to go off. You will not be certain whether or not there is a real fire. As a precaution, use the stairs.
  • If you are outside during an earthquake, stay outside. Move away from buildings, trees, streetlights and power poles. Kneel down and cover your head. Many injuries occur within three metres of the entrance to buildings. Bricks, roofing etc can fall from the building. Trees, streetlights and power lines may also fall, causing injury or damage.

Taken from 'Talking about Disasters' A Guide for Standard Messages.
Produced by the National Disaster Coalition, Washington, D.C. 1999
http://earthquake.usgs.gov/4kids/

Earthquake measurements

Earthquakes may have many intensities but only one magnitude.

Richter Scale (measurement 1 - 9)
This refers to the magnitude of an earthquake and is a measurement of the energy liberated at its source. This may be many kilometres underground.

Modified Mercalli Scale (measurement 1 - 12)
This is a scale of intensity and describes the degree of shaking at a particular point on the earth's surface.

Modified Mercalli Scale

  1. Only detected by seismograph.
  2. Felt by a few people at rest.
  3. Hanging objects swing, heavy truck-like vibrations.
  4. Windows rattle, sensation like a heavy truck striking the building, standing cars rock noticeably.
  5. Felt by most people, sleepers woken, some dishes and windows broken, a few instances of cracked plaster.
  6. Felt by all, trees sway, some heavy furniture moved, some panic, damage slight.
  7. Difficult to stand, walls crack, some chimneys broken, noticed by people driving cars, general alarm.
  8. Branches break, chimneys and weak buildings fall, heavy furniture overturned, some liquefaction, panic.
  9. Most buildings damaged, some move off their foundations, ground cracks appear, underground pipes break.
  10. Many buildings fall down, large landslides, badly cracked ground, landslides considerable on steep slopes and banks.
  11. Most buildings and bridges destroyed, wide cracks in ground, earth slumps and landslides in soft ground.
  12. Total destruction, waves seen on ground surface, cracks open and close, objects thrown up into the air.
Approximate recurrence intervals for strong earthquake shaking in Wanganui

Modified Mercalli Intensity

Average Return Period (years)

6

5

7

50

8

100 to 200
500 to 1000

Taken from the 1997 report on 'Assessment of liquefaction and related ground failure hazards in Wanganui City' by the Institute of Geological and Nuclear Sciences Ltd.

Car Guide

To ride out earthquakes and other emergencies
Although many phones may not work for several hours, know the people you will want to contact when you can get through in an emergency.
My key contacts (keep in car)
Family (out-of-district) contact name / phone number
___________________________________________________________

People authorised to pick up my children at school (with phone numbers)
___________________________________________________________

___________________________________________________________

___________________________________________________________
Other key people and phone numbers
___________________________________________________________

___________________________________________________________

After a disaster, if you are in your car -
DO be patient. DO slow down. If driving in an earthquake, pull over if shaking starts again.
DO turn on the radio, to the nearest operating radio station, for emergency bulletins.
DO proceed cautiously (if safe to do so).
DO obey "road closed" signs.
DO give way to repair and emergency vehicles.
DO NOT attempt to cross damaged roads.
DO NOT go near downed power lines.
DO NOT stop under underpasses or on bridges.
DO NOT drive through water.
DO NOT abandon your car, except if it is unsafe to stay with it. (If you must abandon it, you should not leave it in a traffic lane. If forced to abandon it in a traffic lane, you should leave your keys in it).


Related Links

Frequently Asked Questions

What should I do if there is a Civil Defence emergency?

Where is my nearest Civil Defence centre?

What do I need in my survival kit?

Contacts

Civil Defence Emergency Management:
Phone:
(06) 349-0515 (24 hrs)
Address:
Wanganui District Council,
101 Guyton Street, Wanganui
Email:
Civil Defence


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