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 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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