200,000 Tonnes of Silt and Sand .. picked up and hurled with NZ winds … EYE Report

Posted: Wed Mar 02 2011, 10:17 hrs Christchurch:
Article found HERE

Huge dust storms whip up across Christchurch, hampering rescue operations. (AP)

Strong winds whipped up huge dust clouds in earthquake-hit Christchurch on Wednesday, as officials defended the devastated city’s building standards.

Gusts of 70 kilometres per hour buffeted emergency crews in the ruins of New Zealand’s second largest city, hampering the search for bodies amid fears of masonry dislodging and trees toppling.

“The conditions have been difficult, the wind is picking up and it’s very dusty in the inner city, which is making the rescue efforts more difficult,” district police commander Dave Cliff told reporters.

The winds stirred up an estimated 200,000 tonnes of silt and sand, pushed up from the ground after the power of the February 22 quake loosened the bond between soil particles in a process called liquefaction.

Liquefaction is a phenomenon in which the strength and stiffness of a soil is reduced by earthquake shaking or other rapid loading. Liquefaction and related phenomena have been responsible for tremendous amounts of damage in historical earthquakes around the world.

Search and rescue teams donned respirators as they raked through the wreckage, while supplies of facemasks stockpiled around the country in case of an influenza pandemic — were rushed to Christchurch for residents.