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South Island, New Zealand Earthquake in 2011: Crustal deformation detected by ALOS/PALSAR data

Crustal Deformation Observed by Synthetic Aperture Radar (SAR)

Released: Feb. 27, 2011, Last Updated: Mar. 1, 2011, Japanese version of this page

Crustal Deformation by InSAR

A M=6.3 (USGS) earthquake occurred in the South Island of New Zealand on February 21, 2011 (Local Time: 12:51 on February 22). An interferometric analysis of the data acquired by the Phased Array type L-band Synthetic Aperture Radar (PALSAR) onboard the Advanced Land Observing Satellite (ALOS) allows us to clarify spatial distribution of surface deformation associated with the earthquake.
  • An intensive deformation zone is located in the proximity of the city of Christchurch.
  • A maximum displacement (> 40 cm) close to the satellite is observed at 5~6 km southeast from the city of Christchurch.
  • A major displacement distributes over ~30 km range in the north-south orientation.
  • The observed surface displacement is large relatively for the magnitude (M6.3), maybe suggesting that the depth of fault rupture involved in this event is rather shallow.
  • A simple right-lateral slip of east-west-striking fault cannot account for the observed surface displacement. It suggests that complicated ruptures possibly proceeded.
  • This earthquake is located at the easternmost limit of the afterschocks of the M7.0 September 3, 2010 Earthquake (2010 Canterbury (Darfield) earthquake).
  • We further analyzed the SAR data of interseismic period between the 2010 and the 2011 events. The analysis result shows that a significant surface displacement (~4 cm: relative motion), which is consistent with a displacement distribution resulting from a right-lateral fault motion, is observed at the eastern part of the deformation area due to the 2010 event. The 2011 event is located on the eastward extension of the deformation area.

SOUTH ISLAND, NEW ZEALAND Earthquake

Date-Time February 22, 2011 12:51 (Local Time), February 22, 2011 08:51 (JST)
February 21, 2011 23:51 (UTC)
Hypocenter Location 43.600°S, 172.710°E Depth:5 km (USGS, as of February 26, 2011)
43.581°S, 172.702°E Depth:5 km (GeoNet, as of February 26, 2011)
Magnitude 6.3 (USGS, as of February 26, 2011)
Death Toll  113 (as of February 25, 2011)

Satellite and Sensor

PALSAR sensor onboard "Daichi" (ALOS) satellite launched by Japan Aerospace Exploration Agency on January 24, 2006

Contact

TOBITA Mikio : Head of Division
NISHIMURA Takuya : Chief Researcher
KOBAYASHI Tomokazu : Researcher

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