Christchurch Earthquakes 2010-11

The Christchurch Earthquakes of 2010-11

• A series of earthquakes occurred in and around Christchurch, New Zealand, and the Canterbury Plains region from September 2010 to December 2011.
• The principal event, also known as the Darfield earthquake, struck on September 4, 2010, with a magnitude of 7.0-7.1.
• The epicentre was located 25 miles west of Christchurch, near the town of Darfield, and the focus was 6 miles beneath the surface.
• The earthquake was caused by right-lateral movement along a previously unknown regional strike-slip fault, later named the Greendale Fault.

The Aftershocks

• Thousands of smaller aftershocks occurred in the months that followed the principal event.
• The severest aftershock occurred on February 22, 2011, with a magnitude of 6.3.
• The February 22 aftershock was generated by oblique thrust faulting along a different, undiscovered fault.
• The focus of the aftershock was relatively shallow, only 3 miles beneath the surface of Heathcote Valley, a suburb of Christchurch.

Damage and Casualties

• The February 22 aftershock resulted in substantial shaking, surface cracking, and liquefaction in the city and surrounding area.
• More than 180 people died in the quake, many of whom were killed outright as structures collapsed and debris fell in the streets.
• The Canterbury Television (CTV) building in the city centre was razed almost entirely, with an estimated 100 or more people inside at the time of the quake.

Other Events

• Two large tremors struck the Christchurch metropolitan area on June 13, 2011, with moment magnitudes of 5.6 and 6.3.
• The June 13 events were located farther east of the known extent of the Greendale Fault and appeared to have been generated by strike-slip faulting.
• A series of shallow marine tremors ranging from magnitude 4.0 to 6.0 shook the Christchurch area on December 23, 2011.