Canterbury & Christchurch Earthquakes 2013

Seismic activity in Canterbury and Christchurch New Zealand has acquired a renewed uptick, commencing January 2013.
[For prior documentation of quake events impacting the region, since the initial event of September 4 2010, please refer to posts such as Christchurch Shakes Again and Again. and the end of 2012 summary.]

This post operates like a timeline - scroll to end for latest updates
January 2013 data shows date time, magnitude, depth and location of a strong event.
Jan 19 2013 @ 9.15 pm M4.62, 11.8 kms deep, 380m from 265 Selwyn Rd Rolleston

This magnitude does not fall in the Top 100 range for the region (min Mag 4.74)
but there has not been one of similar size since April 12 2012 M4.60 in the east at New Brighton. Between April 12 2012 and prior to this 2013 event of M4.42, only 4 aftershocks have exceeded M4.6, all in the middle months of 2012, and the last being:

July 6 2012 M4.88  12.62kms deep, 130m from 246 Brookside Rd Rolleston Canterbury

What these two events have in common is their location in the region of  the eastern surface rupturing of the initiating Greendale Fault of September 2010.

On Jan 19 2013 further aftershocks were at 9.48pm (M2.38) - in the region of the first
On Jan 20 2013 two aftershocks ( M3.59, M3.05 occurred in the morning - 7.09, 7.17 am. Both of these were in the region of the western end of the Greendale fault.

A gradual quietening of activity in recent months has lulled locals into less expectation of jolts but local seismologist Mark Chadwick expects aftershocks in the range of M3.
Relatively shallow rumblings have reawakened.

   Updates are added to this 2013 log, as entries below, where necessary

Data from Canterbury Quakelive

January 28 2013
Quakelive provides an intriguing data graphic re the time of day since Sept 4 2010 of quakes in Chch-Canterbury M3+. 
In overall frequency, 2pm is the top ranked time of day for the earth to move in the overall region of Canterbury in this current swag of seismic sequences.
2pm also has a sizeable chunk of the M4+ events - but not the most M5+ - that honour goes to 4am - and its neighbour 5am gets special mention for its top spot in the M4+ category

                                            CLICK to enlarge
As for the Top 5 since Sept 4 2010:

The time frames  around 4am, and 1-3pm also figure significantly

Visit their site for daily updates

January 30 2013
In a surprising development, (due to location) two aftershocks (?)  have occurred this afternoon, south of Akaroa on the seafloor - around latitude 43.53S - M3.79 and M3.11 in close succession

In the Top 100 events (M4.74 is current holder of the 100th position), the aftershock on Oct 8 2011 at 4.17 pm, M4.81, depth 7.18kms is the furtherest south event -  being in Richfield Road, Port Levy, which is 43.40S latitude

February 5 2013
This screenshot shows the latest 25 quakes across the region, largely forming a latitudinal band, with a spread from west to east & into seafloor zones
                                         click to enlarge                       source: Quakemap
The energy graphs on both Quakemap and Quakelive can be read as showing renewed vigour in this phase, occurring since late January 2013

Feb 10 2013
Clustering around New Moon, an area south east of Rolleston is showing a string of quakes up to M3.8, adding vigour to the energy output of this long sequence
                                                                source: Quakemap

Feb 13 2013
The noted focus around Rolleston continues in this snapshot from Quakemap showing the region of most of the prior 25 quakes. 6 of that 25 are in the range M3.3-M3.9 and 3 of this group are in the zone of most activity across the region, circled in image below;

February 22 2013
The two-year anniversary is commemorated in respect of the 2nd and most destructive event in the sequences since Sept 4 2010 - The Press reports
Almost as if in response, the largest shake since Feb 10 occurs in Pegasus Bay - 5 tonnes of energy at 9kms deep, at 2.54 am - yes the current sequence still contains considerable energy, being in a sustained up phase for the past month according to the energy graphs such as Quakemap
Quakelive graphic
Death of a Cathedral - a drone camera filmed inside the Christchurch Cathedral this week, upsetting and frustrating the Bishop Victoria Matthews, who says legal wrangles over the fate of the building are leading it to "die without dignity" with ongoing aftershocks and environmental effects. -
report and video
Interesting that the Christian perspective is so different from the Buddhist when it comes to change, transformation and death.  The acceptance of these three fundamentals of life is so central to Buddhist philosophy yet so problematic in a Christian framework.

A late night M3.9 quake in Pegasus Bay is the largest in the region since 19 January 2013 - this being 9 tonnes, 7.7kms deep around 11pm. Further confirmation of renewed energy in this sequence.

This Quakelive graphic shows that from mid July 2012-mid January 2013 there were repeated lulls in regional activity. since then, continual higher energy events up to M4.6 (Jan 19 2013)

For some perspective:
The initial rural Darfield, Canterbury quake of M7.1 on Sept 4 2010 released 671 kilotonnes of energy 
The next highest quake M6.3 -damaging central Christchurch released 49 kilotonnes
It takes at least a M5.2 to release a kilotonne.
It is currently around a 50/50 or even split in the top 25 quakes as to geolocation - west versus central and east to seafloor.
Clearly the much lower energy releases have extreme destructive potential, and anything over M7 is catastrophic if in an urban density.  

February 25 2013
Three of the largest quakes (M3.2-M3.9, from 8-12kms deep) in recent days have all occurred in Pegasus Bay showing renewed activation there.

March 13 2013
Quake energy across the region has declined since March 4 
Central city Red Zone footage taken recently shows the extent of the CBD still stuck in a time warp
The Press reports: 
The central city remains off-limits to residents.
The red zone, renamed the 'rebuild zone' by politicians, is expected to be reopened by June, although many areas will remain fenced off.

April 2013
The most recent 25 events March 27-April 9 -from M1.9 to M3.0
Coloured dots show variable depths. Though intensity & frequency have declined, recent activity is diverse across the region -north-south-east-west as shown on this clickable graphic from Quakemap

July 2013
After a lull mid May-mid June 2013, quake activity produced more energy in July, with more events over M3
July 29 2013
North Canterbury event felt in Christchurch
A M4.8 event , 9kms deep 20kms n/w of Culverden - south of Hanmer Springs -at 4.37pm confirms a new emphasis in the west and north of Christchurch - with more connection to faults associated with the major Alpine Fault - a specialty subject of Canterbury researcher Tom Robinson -video

PRESS news report July 29

August 2 2013
An uptick is evident in seismic energy output in the Canterbury region in the same time frame as significant quake activity is sustained in the Cook Strait region since July 19
M4.4 Swannanoa area around 4 am on this day
Last 100 quake snapshot from Quakelive shows widespread activity for events M3+ over the past 10 months

Update August 16 2013
This day saw a sudden resumption of high level seismic activity centred in Marlborough, with a M6.6 shake and strong aftershocks. This activity is consistent with the August -High Risk forecast published in June - which indicates further caution is recommended in the latter period of this month. Christchurch/Canterbury may well be registering resonant effects.
August report

update August 22 2013
Seismicity in the larger zone of Canterbury and northwards now figures prominently since the southward drift of quakes from the Seddon Sequence which began in July 2013.

This map segment from Geonet shows a background pattern over the past year with colour coding from grey to blue, green orange in increasing intensity - and does not include the Seddon quakes

September-October 2013
A largely unremarkable period with declining activity prevailing, many lull periods

November 2013
A pattern of very minimal activity interspersed with random higher events is continuing
November 18 M4.6 -via Quakelive
Monday 18 Nov 11.36pm M4.6 in suburban Christchurch, 137 tonnes, being the largest event in the region since October 1st 2013 M4.7 -  a seafloor event off New Brighton
This graphic section from Quakemap shows the pattern over the past year
No events over M5
November 18 2013 is the M4.6 event at extreme far right -and is the 3rd of this level in 12 months.



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