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ALOS-2/PALSAR-2 Observation Result for Eruption of Mt. Kilauea and Earthquake in Hawaii

Posted: May 10, 2018, 4:00 (UTC)
Updated:May 15, 2018, 9:00 (UTC)
Updated:May 21, 2018, 8:00 (UTC)

Overviews

  • On May 3 and 4, 2018, Mt. Kilauea in Big Island, Hawaii, started the eruption.
  • On May 4, a major earthquake of Mw 6.9 (USGS) occurred close to Mt. Kilauea.
  • JAXA performed an emergency observation by ALOS-2 (“DAICHI-2”) on May 8, 2017 (UTC), and ALOS-2 captured part of surface displacement.
  • The interferogram using the two images on May 12, 2018 and Jan. 20, 2018 revealed the wider crustal deformation, and the changes in lava lakes’ level.
  • The interferogram using the two images on May 17, 2018 and Jan. 25, 2018 showed the change in Halemaumau crater due to the explosive eruption on May 17.
  • 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.
On May 3 and 4, 2018, Mt. Kilauea in Big Island, Hawaii, began eruptive activity and JAXA performed an emergency observation with the Phased Array type L-band Synthetic Aperture Radar-2 (PALSAR-2) onboard the Advanced Land Observing Satellite-2 (ALOS-2, "DAICHI-2") on May 8, 2018. Table 1 summarizes the observation data by ALOS-2. Figure 1 shows the topography in Big Island and the observation area by ALOS-2.
Fig. 11

Fig. 1: Topography on Big Island and the observation area by ALOS-2.The red rectangle shows the area by Stripmap mode(data ① in Table 1), and the blue one shows that by ScanSAR mode(data ② in Table 1). The black one shows the area shown in Fig. 5.

Table 1: Summary of the emergency observation of ALOS-2.
Observation time (UTC）Orbit numberObservation modePolarizationObservation directionBeam number
①May 8, 201889Stripmap 10mHH+HVRightF2-6
②May 12, 2018185ScanSARHH+HVRightW2
③May 17, 2018186ScanSARHH+HVRightW2
Figure 2 shows the interferogram using the ALOS-2 PALSAR-2 data acquired on February 27, 2018 and May 8, 2018. This image shows ~70 cm displacement toward the satellite (uplift or westward movement) in northern Leilani Estates. There is also ~60 cm displacement away from the satellite (subsidence or eastward movement) in southern Leilani Estates. Moreover, there is a discontinuity of surface displacement in central part of Figure 2, which may correspond to surface fault along this line.
Fig. 2

Fig. 2: An interferometric image of the ALOS-2 PALSAR-2 data acquired before (February 27, 2018) and after (May 8, 2018) the eruption and earthquake.
(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 ~70 cm displacement toward the satellite movement northern Leilani Estates. There is also ~110 cm displacement along the reverse direction of the satellite traveling in southern Leilani Estates.
Fig. 3

Fig. 3: A Multiple Aperture Interferometry image of the ALOS-2 PALSAR-2 data acquired before (February 27, 2018) and after (May 8, 2018) the eruption and earthquake.
(Click to view enlarged image)

Figure 4 shows a color-composite image (red: Feb 27 HV polarization, green: May 8 HV pol., blue: May 8 HH pol.) where eruptive fissures and lava flow can be seen in red color (red arrows in Fig. 4).
Fig. 4

Fig. 4: Polarimetric color-composite image of the ALOS-2 PALSAR-2 data acquired before (February 27, 2018) and after (May 8, 2018) the eruption and earthquake.
(Click to view enlarged image)

Figure 5 shows the interferogram using the ALOS-2 PALSAR-2 data acquired on January 20, 2018 and May 12, 2018. The wider crustal deformation has been revealed. The image shows ~100 cm displacement toward the satellite in south part from Leilani Estates. Moreover, ~ 50 cm displacement away from satellite was detected around Halemaumau Crater.
Fig. 5

Fig. 5: An interferometric image of the ALOS-2 PALSAR-2 data acquired before (January 20, 2018) and after (May 12, 2018) the eruption and earthquake.
(Click to view enlarged image)

Figure 6 shows comparisons of amplitude images around Halemaumau crater and Pu'u 'O'o crater on May 12 and Jan. 20, 2018. In both craters, terrain inside the craters has changed due to the lowered lava lake level.
Fig. 6

Fig. 6: Comparison of the two HH amplitude images acquired before (January 20, 2018) and after (May 12, 2018) the eruption and earthquake.
(Click to view enlarged image)

Fig. 7: An interferometric image of the ALOS-2 PALSAR-2 data acquired before (January 25, 2018) and after (May 17, 2018) the eruption and earthquake.
Fig. 7

Figure 7 shows the interferogram using the ALOS-2 PALSAR-2 data acquired on January 25, 2018 and May 17, 2018. The result seems similar to that in Fig.5, but there is up to 110 cm displacement away from satellite in Halemaumau crater.
(Click to view enlarged image)

Figure 8 shows a comparison of amplitude images around Halemaumau crater on May 12 and 17. The crater became bigger after the large eruption.
Fig. 8

Fig. 8: Comparison of the two HH amplitude images acquired on May 12, and 17, 2018.
(Click to view enlarged image)

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

Reference

About Pixel offset technique.
JAXA EORC