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Observation Results of ALOS/PALSAR Relating to the Magnitude 7.0 Earthquake in Haiti (2)

On January 12, 2010 (UTC), a magnitude 7.0 earthquake occurred in the Republic of Haiti, in the Caribbean. The Japan Aerospace Exploration Agency (JAXA) performed an emergency observation on January 25 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 compare PALSAR amplitude images taken before and after the earthquake to detect collapsed buildings in inhabited areas including the capital city of Port-au-Prince and conduct differential interferometric SAR (DInSAR) analysis to detect crustal deformation associated with the earthquake using the data acquired on March 9, 2009.

The red and blue rectangles indicate observation areas shown in Figure 2 and Figure 5, 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)

1. Detection of Damaged Area

Reddish or bluish areas in this image indicate change of backscatter for the period, so there is a possibility that some kind of surface change occurred in these areas.

If the radar backscattering weakens after the earthquake, the red-colored image acquired before the earthquake are enhanced in the composite image. Therefore, reddish parts of an inhabited area may correspond to collapses of buildings.
Fig. 2
Fig. 2: A color composite image generated from PALSAR amplitude images acquired before (red: 2009/3/9) and after (green & blue: 2010/1/25) the earthquake
(Click to view enlarged image)
Figure 3 shows Port-au-Prince, the capital, where heavy damages have been reported. In this figure and Figure 4, there are many reddish dots or areas in the color composite images. These suggest that many buildings collapsed in the city of Port-au-Prince and an inhabited area about 7 km north of the city.
Fig. 3
Fig. 3: An enlarged amplitude image around Port-au-Prince (left) and a color composite image (right) enclosed by the red rectangle in Figure 2
(Click to view enlarged image)
Fig. 4
Fig. 4: An enlarged amplitude image around the north of Port-au-Prince (left) and a color composite image (right) enclosed by the blue rectangle in Figure 2
(Click to view enlarged image)

2. Detection of Crustal Deformation

Figure 5 left is an interferogram generated from PALSAR data acquired before (2009/3/9) and after (2010/1/25) the earthquake using the DInSAR technique. A color pattern illustrates changes of satellite-ground distance for the period. Figure 5 right is a PALSAR amplitude image acquired after the earthquake indicating an observation field of 200 km from north to south.
Fig. 5: PALSAR interferogram
Fig. 5: PALSAR interferogram
(Click to view enlarged image)
Fig. 5: PALSAR amplitude image
Fig. 5: PALSAR amplitude image
(Click to view enlarged image)
In the interferogram of Figure 5 (left) and Figure 6, there are so many color fringes in west of the epicenter. It is interpreted that relative displacements at the center of the color fringes (A) are at least 70.8 cm. Moreover, we can see another eyed pattern of color fringe in north of the epicenter. This suggests a complicated distribution of crustal deformation.
Fig. 6
Fig. 6. An enlarged interferogram enclosed by the red rectangle in Figure 5 (left)
(Click to view enlarged image)

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

JAXA EORC