Reviewed by USGSNew Zealand15y ago
M4.3 earthquake 9 km WSW of Burnham, New Zealand
Friday, July 22, 2011, 19:45:39 UTC · 43.646°S, 172.207°E
A magnitude 4.3 earthquake struck 9 km WSW of Burnham, New Zealand on Friday, July 22, 2011, 19:45:39 UTC, at a depth of 11.1 km (shallow).
- Magnitude
- 4.3
- Light · ml
- Depth
- 11 km
- Shallow
- Felt reports
- 0
- Did You Feel It?
- Est. shaking
- —
- No ShakeMap
- PAGER alert
- None
- Not issued
- Tsunami
- No flag
- USGS feed
Outlined circle: this earthquakeDashed circle: 50 km aftershock search area
In context
How big was it, and why here?
Energy released
43 tons of TNT
That is about 1/354 of the Hiroshima bomb. A magnitude 5.0 releases about 11 times more energy.
Tectonic setting
117 km
from the nearest mapped plate boundary, between the Australian and Pacific plates. Earthquakes this far from a boundary happen on faults inside a plate, often less frequently but sometimes strongly.
Depth: shallow
11 km
Shallow earthquakes (under 70 km) produce the strongest surface shaking for their size, so they are the ones most likely to cause damage near the epicenter.
Did You Feel It?
Where it was felt
No “Did You Feel It?” reports have been published for this event yet. If you felt it, you can add your report on the USGS website.
I felt it — report to USGS ↗USGS PAGER estimate
Who was exposed to shaking
USGS publishes PAGER impact estimates for significant earthquakes, usually within an hour. No PAGER estimate is available for this event.
After the main event
Aftershocks within 50 km
USGS lists 4 M2.5+ earthquakes within 50 km in the following 30 days; the largest was M4.1 on August 19, 2011. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.
Regional history
Past M5+ earthquakes within 300 km
USGS lists 74 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 7.368 km S of Wakefield, New ZealandJune 16, 1929 · 200 km NE of this epicenter
- 7.138 km E of Westport, New ZealandMay 23, 1968 · 214 km N of this epicenter
- 7.030 km NW of Amberley, New ZealandMarch 9, 1929 · 76 km N of this epicenter
- 7.019 km NE of Methven, New ZealandSeptember 3, 2010 · 33 km NW of this epicenter
- 6.856 km NW of Oxford, New ZealandJune 18, 1994 · 88 km NW of this epicenter
- 6.535 km NNW of Methven, New ZealandJune 26, 1946 · 70 km NW of this epicenter
- 6.558 km SW of Wakefield, New ZealandJune 22, 1929 · 206 km N of this epicenter
- 6.471 km NNE of Amberley, New ZealandMay 22, 1948 · 139 km NE of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 15 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 209 recorded deaths. The most severe:
- 2011M6.1
Christchurch, Lyttelton
21 Feb 2011 · 39 km away
185 deaths$15 billion damagetsunami
- 1929M7.5
South Island
16 Jun 1929 · 211 km away
17 deathsModerate damage ($1–5M)tsunami
- 1968M7.1
South Island: Nw Coast
23 May 1968 · 217 km away
3 deaths$3 million damage
- 1848M6.0
Awatere River, Marlborough
18 Oct 1848 · 264 km away
3 deathstsunami
- 2011M6.0
South Island: Canterbury
13 Jun 2011 · 44 km away
1 death$3.0 billion damage
- 2010M7.0
Christchurch
3 Sep 2010 · 33 km away · intensity IX
$6.5 billion damage
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.