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The 2016 Kumamoto Earthquake: Crustal deformation around the faults

Crustal Deformation around the Faults Revealed by MAI analysis

Released: Apr. 28, 2016 Japanese version of this page

Features of Crustal Deformation

A large earthquake (M7.3) occurred in Kumamoto, Japan on April 16, 2016. We applied MAI (Multiple Aperture Interferometry) analysis using ALOS-2/PALSAR-2 data, and revealed the crustal deformation around the faults which the standard InSAR technique could not detect.
  • Along-track displacement (almost north-south direction) shows northward deformation (red) in the northern area of the Futagawa fault zone and southward deformation (blue) in the southern area. The amount of the deformation reaches about 1 m at a maximum. The observed deformation pattern is consistent with right-lateral fault deformation.
  • There are sudden changes of the direction of the deformation along the Futagawa fault zone. Surface ruptures are identified in some areas.
  • The changes of the direction of the deformation along the Futagawa fault zone are linearly seen from a junction with the Hinagu fault zone in the west to a few kilometers east of the west rim of Aso caldera in the east.
  • The gradient of the deformation is high along the Hinagu fault zone, which implies that fault motion also occurred in the northern part of the Hinagu fault zone.

NOTE: The MAI technique is still under investigation, and this is a preliminary result. The result is possibly updated with further elaborated analyses.

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Figure 1. Blue and red areas represent forward (almost southward) and backward (almost northward) horizontal deformation of the flight direction.

* We also confirmed that the result of the pixel offset method showed a corresponding crustal deformation.

The 2016 Kumamoto Earthquake (main shock)

Date-Time April 16, 2016 01:25 (JST)
April 15, 2016 16:25 (UTC)
Hypocenter
Location
32.7545°N, 130.7630°E, Depth: 12 km
(JMA, as of April 28, 2016)
Magnitude 7.3 (JMA, as of April 28, 2016)
Death Toll 49 (as of April 28, 2016)

Satellite

ALOS-2 (Advanced Land Observing Satellite 2) launched by Japan Aerospace Exploration Agency on May 24, 2014

Paper, Report, Presentation

In preparation

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Contact

YARAI Hiroshi : Head of Division
KOBAYASHI Tomokazu : Chief Researcher
MORISHITA Yu : Researcher
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