http://msnbcmedia.msn.com/j/MSNBC/Components/Slideshows/_production/ss-110221-new-zealand-quake/ss-110221-nz-quake-10.ss_full.jpg

Christchurch cathedral

Magnitude 6.3 - SOUTH ISLAND OF NEW ZEALAND

http://msnbcmedia.msn.com/j/MSNBC/Components/Slideshows/_production/ss-110221-new-zealand-quake/ss-110221-nz-quake-10.ss_full.jpg

Christchurch cathedral

Reasons for high levels of loss:

1)Location of the earthquake2)Peak ground accelerations3)Nature of the buildings4)Ground conditions5)Time of dayhttp://blogs.agu.org/landslideblog/2011/02/23/on-the-causes-of-the-high-levels-of-loss-in-the-christchurch-earthquake/

http://earthquake.usgs.gov/earthquakes/eqarchives/poster/2011/20110221.php

Canterbury M7.2 earthquake Sept. 4 2010 M6.3 aftershock Feb. 21, 2011

All aftershocks since Sept. 4 2010 (red are deep; star is Feb 21, 2011 event)

http://www.christchurchquakemap.co.nz/week

http://earthquake.usgs.gov/earthquakes/eqarchives/poster/2011/20110221.php

http://www.geonet.org.nz http://www.geonet.org.nz

Shaking intensity in the city was much greater for this earthquake than the magnitude 7.1 earthquake from last September, or any of the aftershocks. The highest shaking was recorded at Pages Road Pumping Station at 188 %g, with readings of 127 %g at Heathcote Valley Primary School and 107 %g at Hulverstone Road Pumping Station.

This is due to the proximity of the epicentre to the city and the shallow depth. The earthquake has a reverse faulting mechanism.

http://www.geonet.org.nz/news/feb-2011-christchurch-badly-damaged-by-magnitude-6-3-earthquake.html

Nature of the buildings: good earthquake building safety regulation, but old ones are hard to retrofit and this was very strong shaking even for newish buildings

http://www.nzherald.co.nz/christchurch-earthquake-photos

http://media.nzherald.co.nz/webcontent/image/jpg/20119/st6201.jpg

Ground conditions and liquefaction

http://blogs.agu.org/landslideblog/files/2011/02/11_02-New-Zealand-damage.jpg

Time of day: people are out and about at 11 am

http://www.stuff.co.nz/4688231/Large-quake-strikes-Christchurch

Important implications for the effects of M6 earthquakes in places like the US mid continent where some think that there would be only modest damage from such events.

 http://www.guardian.co.uk/world/gallery/2011/feb/22/new-zealand-earthquake-in-picture