August 21, 2003 Tsunami: South Island, New Zealand
A tsunami caused by a magnitude 7.2 earthquake and a landslide began at South Island, New Zealand on August 21, 2003 at 12:12:49 UTC. The water rose as high as 4 meters. Its effects were recorded at 3 places in at least 2 countries.
Where the waves reached
The source (white) and every runup with a place, colored by the water height recorded there. A ring is a runup NCEI marks doubtful.
- Under 1 m
- 1 to 3 m
- 3 to 10 m
- 10 to 30 m
- 30 m and more
- Height not recorded
Travel times
How long the first wave took to reach each part of the ocean, one line for each hour up to 24, estimated from the source and the depth of the sea.
The travel times are computed in your browser, which needs JavaScript.
- 1 to 4 hours
- 5 to 6 hours
- 7 to 14 hours
- 15 hours and more
Computed in your browser the way NOAA’s own travel time maps are: the wave travels at the square root of gravity times the depth, over NOAA’s ETOPO1 depths averaged to a 10 arc-minute grid. Checked against NOAA NCEI’s maps for 21 tsunamis over the first 24 hours, these lines fall within 10 minutes of NCEI’s at half the points compared and within 52 minutes at 9 in 10. They give when the first wave could arrive, not how high it is; bays, harbors and island chains finer than the grid can see it later. Not for use in a warning: see tsunami.gov.
The tsunami
- Date
- August 21, 2003, 12:12:49 UTC
- Source
- South Island, New Zealand
- Cause
- Earthquake and landslide
- Earthquake
- Magnitude 7.2, 28 km deep
- Maximum water height
- 4 m (13.1 ft)
- Runups recorded
- 3
- Waters
- Ocean
- How certain
- Definite tsunami
- Source location
- 45.104° S, 167.144° E
The toll
- Injuries
- Few (about 1 to 50) with the earthquake or eruption that caused it
- Damage
- Limited (under about $1 million)
Where the literature gives no number, NCEI records a description on a scale of 1 to 4, printed here in its words. Damage is in millions of US dollars of the year of the event, not adjusted for inflation.
What the record says
NCEI’s account, from the sources it cites.
A small tsunami with a maximum wave height (peak-to-trough) of 30 cm was recorded at Jackson Bay in Westland. A seiche of 15 cm was observed at Port Kembla, Australia. (from reference #1053)
Fortunately, because of the remote location, the earthquake resulted in few injuries and relatively minor damage to property. However the earthquake triggered many landslides on the steep slopes that typify Fiordland. The fall of one landslide into Charles Sound caused a small local tsunami that reached a maximum of 4-5 m above high tide mark on the opposite shore. A small tsunami was also generated on the Tasman Sea coast, which was recorded on tide gauges at Jackson Bay (300 mm peak-to-trough) 190 km northeast of the epicentre, and at Port Kembla (170 mm peak-to-trough) on the east coast of Australia. Spectrogram analyses are used to demonstrate that the observed tide-gauge signals are best explained by the excitation of local resonances by the trans-Tasman tsunam […] Evidence has been found for two tsunami generated in response to the earthquake. One tsunami was generated by a substantial rock slide into Charles Sound, this tsunami was confined to a small area, yet reached heights of 4-5 m, and caused damage to vegetation and a wharf. The second tsunami was of relatively small amplitude, but is believed to have propagated widely around the Tasman Sea. (reference #3808)
Every runup
Nearest the source first. Heights are above sea level at the time; a tide gauge reads half the wave’s full height.
| Where | Country | Km from source | Water height, m | Inland, m | Measured by | First wave, UTC | Deaths |
|---|---|---|---|---|---|---|---|
| Charles Sound | New Zealand | 4 | 4 | Eyewitness observation of water height | |||
| Jackson Bay | New Zealand | 172 | 0.15 | Tide gauge (half the maximum wave height) | day 21, 14:13 | ||
| Port Kembla | Australia | 1,818 | 0.07 | Tide gauge (half the maximum wave height) | day 21, 15:39 |
More
Every tsunami in 2003The 2000sTsunamis of New ZealandThe earthquakeThis day in weather historyAlerts in force
Sources
Tsunami events and runups from NOAA’s National Centers for Environmental Information, Global Historical Hazard Database, cited as NCEI/WDS, doi:10.7289/V5PN93H7. Public domain. Read 2026-09-24. NCEI tsunami event 2953.