Land observing by ALOS-2

Observation Results for Eruption of Shinmoedake by ALOS-2 and COSMO-SkyMed

Posted: Mar. 26, 2018, 9:00 (UTC)

Overviews

On March 1, 2018, Shinmoedake in southern Kyusyu, Japan began eruptive activity.
JAXA has performed an emergency observation with the Phased Array Type L-band Synthetic Aperture Radar-2 (PALSAR-2) aboard Advanced Land Observing Satellite-2 (ALOS-2, “DAICHI-2”) since March 6, 2018. The ALOS-2 images revealed development of a lava dome in the crater.
COSMO-SkyMed also observed the enlargement of the lava dome more clearly and detected the lava movement.
The observation image on March 19 shows that the lava which flowed out to outside the crater still flows and the developing speed of the lava dome of crater inside has been decreasing.
We will contentious observe there to monitor volcanic activities using ALOS-2 which can observe earth surface regardless of clouds, volcanic plumes, and sun light.

On March 1, 2018, Shinmoedake in southern Kyusyu, Japan, began eruptive activity. It has subsequently occurred off and on, and the lava was observed on March 6. At 14:30 on that day, there was an explosive eruption. On March 9, the lava flowed out from the northwestern part of the crater. Although the volcanic activity has been weakened, the volcanic earthquake has been yet observed as of the morning on March 16.
JAXA was requested from Japan Meteorological Agency to perform an emergency observation with the Phased Array Type L-band Synthetic Aperture Radar-2 (PALSAR-2) aboard Advanced Land Observing Satellite-2 (ALOS-2, “DAICHI-2”) since March 6 2018, and the observed data are provided to related institutions. Moreover, JAXA requested ASI (Agenzia Spaziale Italiana, Italian Space Agency) to perform an emergency observation by COSMO-SkyMed and was provided the data. The datasets of ALOS-2 and COSMO-SkyMed are listed in Table 1 and Table 2.

Table 1: List of Observations by ALOS-2

	Observation time（UTC）	Orbital No.	Mode	Orbit	Direction	Beam No.
(1)	3:18, Jan. 22, 2018	23	Stripmap	Des.	Right	U2-7
(2)	3:18, Mar. 5, 2018	23	Stripmap	Des.	Right	U2-7
(3)	14:30, Mar. 6, 2018	124	Stripmap	Asc.	Left	U3-11
(4)	3:04, Mar. 9, 2018	21	Stripmap	Des.	Right	U3-13
(5)	3:25, Mar. 10, 2018	24	Spotlight	Des.	Right	-
(6)	14:16, Mar. 10, 2018	122	Spotlight	Asc.	Left	-
(7)	14:36, Mar. 11, 2018	125	Stripmap	Asc.	Left	U2-8
(8)	3:11, Mar. 14, 2018	22	Stripmap	Des.	Right	U3-10
(9)	14:23, Mar. 15, 2018	123	Stripmap	Asc.	Left	U3-14

Table 2: List of Observations by COSMO-SkyMed

	Observation time（UTC）	Mode	Orbit	Direction	Beam ID	Satellite No.
(1)	20:12, Mar. 7, 2018	Spotlight	Asc.	Left	24	S2
(2)	8:53, Mar. 8, 2018	Spotlight	Des.	Right	23	S1
(3)	21:12, Mar. 9, 2018	Spotlight	Asc.	Right	27	S4
(4)	22:56, Mar. 10, 2018	Spotlight	Asc.	Left	17	S1
(5)	8:59, Mar. 11, 2018	Spotlight	Des.	Right	16	S2
(6)	8:59, Mar. 12, 2018	Spotlight	Des.	Right	16	S3
(7)	8:59, Mar. 15, 2018	Spotlight	Des.	Right	16	S4
(8)	8:59, Mar. 19, 2018	Spotlight	Des.	Right	16	S1

Fig. 1: Map of southern Kyusyu, Japan. The red triangle shows the location of Shinmoedake.

Fig.2:(upper-left)Images acquired on 22th January 2018

Fig.2:(upper-center)Images acquired on 3rd March 2018

Fig.2:(upper-right)Images acquired on 6th March 2018

Fig.2:(middle-left)Images acquired on 9th March 2018

Fig.2:(middle-center)Images acquired on 10th March 2018(Descending)

Fig.2:(middle-right)Images acquired on 10th March 2018(Ascending)

Fig.2:(lower-left)Images acquired on 11th March 2018

Fig.2:(lower-left)Images acquired on 14th March 2018

Fig.2:(lower-right)Images acquired on 15th March 2018

Fig. 2: Observation images around the crater by ALOS-2. The upper-left number corresponds to that in Table 1.
(Click to view enlarged image)

Figure 2 shows the observation images around the crater of Shinmoedake by ALOS-2. These images were acquired from eastern side of Shinmoedake. Comparing with the image on (1) Jan. 22, we confirmed some changes in the crater in the image on (2) Mar. 5, and a lava dome was formed on (3) Mar. 6. The dome had enlarged time by time, and the lava flowed out to the northwest direction on (5) Mar. 10. The dome continued to get larger and it covered almost all of the crater on (9) Mar. 15. You can see how the dome has been developed by animation on Fig. 3.

Fig. 3: Animation movie composed of ALOS-2 images

Fig.2:(upper-left)Images acquired on 7th March 2018

Fig.2:(upper-center)Images acquired on 8th March 2018

Fig.2:(upper-right)Images acquired on 9th March 2018

Fig.2:(middle-left)Images acquired on 10th March 2018

Fig.2:(middle-center)Images acquired on 11th March 2018

Fig.2:(middle-right)Images acquired on 12th March 2018

Fig.2:(lower-left)Images acquired on 15th March 2018

Fig.2:(middle-center)Images acquired on 19th March 2018

Fig. 4: Observation images around the crater by COSMO-SkyMed. The upper-left number corresponds to that in Table 2.
(Click to view enlarged image)

Figure 4 shows the observation images around the crater of Shinmoedake by COSMO-SkyMed. COSMO-SkyMed uses X-band microwave (wavelength: 3.1 cm) and we can clearly recognize the outline of the lava dome and the surface striped patterns. Comparing observation image on March 15 with that on March 19, we confirm the lava which flowed out into crater outside still flows and the lava dome has been enlarging. Fig. 5 is an animation composed of the latest three COSMO-SkyMed images. You can see the enlargement of lava done more clearly.

Fig. 5: Animation movie composed of COSMO-SkyMed images

Fig. 6: Lava movement derived from COSMO-SkyMed images obtained on Mar. 11 and Mar.12 using pixel offset technique. Left figure shows the displacement along the range direction. Right figure is that along the azimuth direction.

Figure 6 shows the lava movement in the crater derived from pixel offset (or offset tracking) technique. The pixel offset is a robust method to detect localized large displacement at precise coregistration of two images. Applying this method to COSMO-SkyMed images acquired on Mar. 11 and Mar. 12, approx. 12 m along range (i.e. west) direction and approx. 15 m along azimuth (i.e. south) direction were detected. This movement is recognized in the animation in Fig. 5.

Fig. 7: Lava movement derived from COSMO-SkyMed images obtained on Mar. 15 and Mar.19 using pixel offset technique. Left figure shows the displacement along the range direction. Right figure is that along the azimuth direction.

Figure 7 also shows the lava movement derived from COSMO-SkyMed images acquired on Mar. 15 and Mar. 19. Approx. 15 m along range (west) direction and approx. 20 m along azimuth (south) direction were detected during four days, indicating the developing rate of the lava dome has been decreasing.

We will continue to monitor Shinmoedake by ALOS-2.

© JAXA EORC

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