Posted: May 23, 2018, 9:00 (UTC)
Updated: Jun. 1, 2018, 8:00 (UTC)

Overviews

• Mt. Kilauea in Big Island, Hawaii, has been erupting since May 3.
• JAXA performed an emergency observation by ALOS-2 (“DAICHI-2”) on May 22, 2017 (UTC), and captured surface displacement and area of lava flow.
• The interferogram using the two images on May 26, and May 12, 2018 showed the eastward movement of deformation area around Leilani Estates and expansion of that around Halemaumau Crater.
• The observation image on May 30, 2018 showed the expansion of Halemaumau Crater.
• The observation data were provided to local institutions. ALOS-2 will be able to be contributed to monitor volcanic activity regardless of clouds, volcanic plumes, and sun light.

*Please see ALOS-2/PALSAR-2 Observation Result for Eruption of Mt. Kilauea and Earthquake in Hawaii for observations before May 22.

Fig. 1: Topography on Big Island and the observation area by ALOS-2. The red rectangle shows the area by data ① in Table 1, the blue one by data ②, and the yellow-green one by data ③, respectively. The black one shows the area shown in Fig. 6.

Fig. 2: An interferometric image of the ALOS-2 PALSAR-2 data acquired May 8 and May 22, 2018.
(Click to view enlarged image)

　Figure 2 shows the interferogram using the ALOS-2 PALSAR-2 data acquired on May 8 and 22, 2018. This image shows ~150 cm displacement toward the satellite (uplift or westward) in northern Leilani Estates. There is also tens of centimeters displacement away from the satellite (subsidence or eastward) in southern Leilani Estates.

Fig. 3: A Multiple Aperture Interferometry image of the ALOS-2 PALSAR-2 data acquired May 8 and May 22, 2018.
(Click to view enlarged image)

　Figure 3 shows the result by Multiple Aperture Interferometry using the same data in Fig.2. This technique can derive the displacement along the direction of the satellite traveling. The image shows displacements toward the flight direction and the reverse direction of the satellite traveling up to 3 meters.

Fig. 4: Polarimetric color-composite image of the ALOS-2 PALSAR-2 data acquired before (February 27, 2018) and after (May 22, 2018) the eruption and earthquake.
(Click to view enlarged image)

Fig. 5: An enlarged image of the area of the red frame in Figure 4.
(Click to view enlarged image)

　Figure 4 shows a color-composite image (red: Feb 27 HV polarization, green: May 22 HV pol., blue: May 22 HH pol.) where eruptive fissures and lava flow can be seen in red color. Figure 5 shows an enlarged image around Leilani Estates (the area of the red frame in Figure 4).

Fig. 6: An interferometric image of the ALOS-2 PALSAR-2 data acquired May 12 and May 26, 2018.
(Click to view enlarged image)

　Figure 6 shows the interferogram using the ALOS-2 PALSAR-2 data acquired on May 12 and 26, 2018. Comparison between this figure and the previous interferograms (Jan. 20 and May 12, Jan. 25 and May 17) revealed that the deformation area around Leilani Estates has moved eastward. Moreover, the deformation area around Halemaumau Crater has been expanding comparing with the previous interferograms.

　Figure 7 shows a comparison of amplitude images around Halemaumau crater on May 30 and 17. The crater has been getting bigger since the large eruption on May 17.

　We will continue to monitor Mt. Kilauea by ALOS-2.

Reference:
ALOS-2/PALSAR-2 Observation Result for Eruption of Mt. Kilauea and Earthquake in Hawaii.
About Multiple Aperture Interferometry.

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