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Observation Results of ALOS/PALSAR Relating to the Magnitude 8.8 Earthquake in Chile, 2010 (1)

On February 27, 2010 (UTC), a magnitude 8.8 earthquake occurred off the coast of middle Chile, in the South America. The Japan Aerospace Exploration Agency (JAXA) performed an emergency observation on March 2 using the Phased Array Type L-band Synthetic Aperture Radar (PALSAR) installed on the Advanced Land Observing Satellite (ALOS) to determine the state of damage caused by the earthquake. In this report, we conducted differential interferometric SAR (DInSAR) analysis to detect crustal deformation associated with the earthquake using the data acquired on January 15, 2010.

The blue rectangle indicates observation areas shown in Figure 2, and the red star represents the epicenter.
Fig.1: An overall view of the observation area
Fig.1: An overall view of the observation area (We refer to SRTM3 as terrain data.)
(Click to view enlarged image)
Figure 2 left is an interferogram generated from PALSAR data acquired before and after the earthquake using the DInSAR technique. A color pattern illustrates changes of satellite-ground distance for the period. Figure 2 right is a PALSAR amplitude image acquired after the earthquake indicating an observation field of 250 km from south to north. In the interferogram, there are so many color fringes up to 28 cycles. It is interpreted that ground movement towards to the satellite around northwestern coastal area relative to the southeastern inland area are about 3m. Considering a mechanism of this earthquake, the color pattern indicates an uplift or westward displacement.
図2: (左)PALSAR差分干渉画像(地殻変動図)
Fig.2: PALSAR interferogram showing deformation map
(Click to view enlarged image)
図2: (右)地震後のPALSAR強度画像
Fig.2: PALSAR amplitude image
(Click to view enlarged image)

JAXA plans to continue ALOS observations of the afflicted area in Chile.

* The color changes from red, blue, green, yellow and back to red indicate an shortening of the satellite-ground distance, and one color cycle = 11.8cm.