Earthuakes were prominent in news in 2016 and for good reason – not only was there on of the biggest recorded earthquakes in New Zealand history, there were a record number of earthquakes recorded.
Number of earthquakes:
- about 20,000 on average per year
- 29,000 recorded in 2011 (a bad year in Christchurch)
- 38,828 earthquakes recorded in 2016
This is a big jump but it’s not really surprising given the chain reaction across multiple faults in the North Canterbury shakes last year.
Most of those were recorded by sensitive instruments and wouldn’t have been felt, but there were still quite a few that shook enough to be noticed.
- 7.0 or more – 2 (7.8 and 7.1)
Geonet: 2016 in review: The Groundbreaker
The M.7.8 Kaikoura earthquake will not go into the global history book of earthquakes because of its magnitude; the Ring of Fire regularly gets that size and much larger earthquakes. What makes it unique is two things: how it ruptured across the faults through the North Canterbury and Marlborough Fault areas and the slow-slip earthquakes triggered by M7.8.
- 6.0-6.9 – 10
- 5.0-5.9 – 122
Geonet Facts and Stats:
| Frequency of New Zealand Earthquakes (1960 to 2015) | ||||
| Magnitude | Annual Average | Minimum | Maximum | “Rule of Thumb” |
| 4.0 – 4.9 | 451 | 184 | 1,343 | 1 per day |
| 5.0 – 5.9 | 51 | 19 | 127 | 4 per month |
| 6.0 – 6.9 | 2.7 | 0 | 9 | 5 per 2 years |
| 7.0 – 7.9 | 0.4 | 0 | 2 | 1 per 2.5 years |
| 8.0 or over | 0 | 0 | 0 | 1 per century* |
| * Based on geological investigations and historical record of earthquakes. | ||||
So there were significantly more than average in 2016.
There have been many images of the many fault lines, land slips and broken land.
The latest images were taken from planes by Land Information New Zealand (Linz) and the NZ Transport Agency (NZTA), and are here.
Stuff has some before and after slide views in Before and after the Kaikoura quake: images show colossal damage.
Pete George
/ 4th January 2017Meanwhile a bit further north:
M7.2 – 221km SW of Nadi, Fiji
2017-01-03 21:52:31 UTC
19.328°S 176.056°E
15.2 km depth
http://earthquake.usgs.gov/earthquakes/eventpage/us10007pj6#executive
Far enough offshore it won’t have caused too much damage, hopefully, but there’s a tsunami warning for Fiji (not for New Zealand).
Kitty Catkin
/ 4th January 2017I need glasses…..I thought that you said that there were 38,828 earthquakes last year….(faints at the mere thought)
Brown
/ 4th January 2017Our stats are over such a short period in the scheme of things there’s no reason to be excited – its just a number without enough context to draw long term conclusions from. For example, I wonder what 1855 or 1942 were like? We don’t know because we couldn’t measure as accurately then and the thousands of small ones we don’t notice through our backsides went unrecorded. Plate tectonics as we know it today only dates back to the 1960’s (although it germinated conceptually in 1915) so its a relatively new and exciting field which includes earthquakes.
NOEL
/ 4th January 2017Wasn’t really fazed on getting the survival gear together when quakes originated in Chile with heaps of time to move.
But the new slow slip hypothesis and its short arrival time has got me moving
Trouble is I will probably only be half way up the nearest hill when the tsunami arrives..