Sunday, November 13, 2016

Accumulating links and interpretation for earthquake M7.8 - 53km NNE of Amberley, New Zealand

I am accumulating some links and thoughts with respect to today's earthquake M7.8 - 53km NNE of Amberley, New Zealand. I hope that the damage won't be too severe and I am sending positive energy to the people there. Magnitude and depth were increasing as the seismologists reviewed the seismograms. It was felt widely across New Zealand (Felt reports:

>15,000 felt reports as of 17:14 UTC

Here is a sketch of the NZ tectonic setting (from

March 6, 2017 update:
GNS updates including offshore faulting from high resolution bathymetry

Jan. 1-4 updates:
GNS field work blog
New Zealand Geographic article
Before and after images

Dec. 5 updates:
Kekerengu Fault field work blog

Nov. 28 updates:
Kekerengu Fault and prior trenching (GNS)

Nov. 27 updates:
Repeat satellite imagery showing big shift! (Chris Milliner)
Geospatial Information Authority of Japan interesting differencing
EarthJay blog post

Nov. 25 updates:
Farm track ruptured by fault drone video
The Kekerengu Fault rupture pictures from Julian's Rock and Ice Blog

Nov. 23 updates:
NPR report with some of the amazing drone videos and other commentary
Temblor site with some of the amazing drone videos and other commentary

Nov. 21 updates:
Amazing drone video of the Kekerengu Fault rupture
Kaikora coastal uplift
Skateboarders making the most of the rupture....
Rob Langridge GNS Science talks earthquakes with JR

Nov. 19 updates:

GeoNET: viewing the earthquake from space
GeoNET: measuring the earthquake with GPS
Fagereng, Complex Earthquake Raises Complex Questions (EOS)
Trembling Earth blog entry 2

Nov. 17 updates:
Evolving magnitudes on quakestories
Preliminary landslide mapping

Nov. 15 and 16 updates:
GNS Blog
Trembling Earth blog entry 1
COMET for interferogram and interpretation
Kaikoura district faults report by GNS
Temblor interpretation
Commentary in Spinoff--GNS scientists interviewed
Science commentary
Duffy and Quigley commentary in the Conversation
Tsunami damage Banks Peninsula
Digital Globe images of surface rupture from Ryan Gold (USGS)
Preliminary Sentinel-1 interferogram
Yahoo News Seafloor uplift article

Nov. 14 updates:
Geonet what we know so far
Geonet update
IRIS Recent Earthquake Teachable moment
IRIS Special Event Site: South Island, New Zealand
Surface rupture, landslides, damage:

Nov. 13 Interpretion: The magnitude and depth (as long as it does not get much deeper) could be consistent with a rupture on the Hope Fault. The location and to some degree the focal mechanism would be more consistent with one of the thrust faults further to the west. As information has flowed in, I get a sense that the rupture was deeper and mostly underneath the main crustal faults and approaching the subduction interface below.

Reports are coming in that there is a tsunami that was generated and has hit the coast with heights of a few meters in places.

Interesting to see aftershocks aligned along the faults to the northeast. USGS tectonic summary suggested some slip along the megathrust. I wonder if it is in a sort of accretionary complex above the megathrust and transitioning into to the shearing plate boundary (hence the depth and steeper dip and oblique slip focal mechanism). USGS finite fault and source time function show deeper slip almost 100 km northeast (and 60 seconds) from the hypocenter (making this a complex earthquake). Peak slip is ~ 4m (oblique) at about 25 km down dip distance from the surface along a 38 degree to the NW dipping surface. See also IRIS backprojection results. But that is necessarily a simple model. The Cape Campbell GPS station moved 2 m E, 1 m N, and 1 m up apparently (scroll down) and that would imply shallower or greater or more complex slip than the simple inversion implies. It makes me wonder what surface rupture will look like. USGS finite fault source now indicates strong ground motions and likely seafloor uplift zone (Kaikora to almost Wellington; see the image below).

Here is a mashup of GNS faults with the USGS location, shaking estimates, additional earthquakes, and focal mechanism as of 16:23 UTC:

Links (some coming from twitter feed)

News links:

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