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Mw 6.3 Christchurch Earthquake

Scientists at the EERC are currently processing strong-motion (SM) data from the Mw 6.3 earthquake on February 21 2011 at 23:51 GMT the epicentre of which was located about 10 km south-east of Christchurch City Centre in the South Island of New Zealand. The SM data obtained from the GeoNet website http://www.geonet.org.nz is being analyzed by Dr. Rajesh Rupakhety by using new methodologies and computer programs developed at the EERC.

Dr. Rupakhety has mapped the variation of PGA in the epicentral region (Figure 1: Map1) which indicates large peak ground accelerations (PGA), with a maximum vertical acceleration of 1.9g (g being acceleration of gravity) at the Pages Road Pumping Station in Christchurch (Figure 2: acc).

Preliminary results indicate strong evidence of ground motion amplification due to local soil conditions in the Christchurch area. Severe long-period pulses and significant permanent ground displacements, characteristic of near-fault earthquake ground motion, are observed at several stations near the epicentre.

A detailed investigation of the recorded and processed earthquake motion (co-seismic ground displacement, localized amplification of ground motion, characteristics of long-duration velocity pulses, etc.), and the corresponding structural response to the earthquake action is underway.

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