The 2021 Qinghai Earthquake: Crustal deformation detected by ALOS-2 data

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Crustal Deformation Observed by Synthetic Aperture Radar (SAR)

Released: May 25, 2021, Update: May 26, 2021, Update: Jun. 8, 2021, Update: Jun. 28, 2021 Japanese version of this page

Summary

An earthquake (M 7.3, USGS) occurred in Southern Qinghai, China on May 21, 2021 (UTC). To measure the crustal deformation caused by this earthquake, we applied interferometric analysis using ALOS-2/PALSAR-2 data. The analysis result shows the spatial distribution of crustal deformation clearly.

An intensive deformation zonally extends in EES-WWN direction.
A displacement discontinuity with ground displacement exceeding 1 m can be identified. In the western side of the epicenter, the discontinuity is observed along the known active fault. On the eastern side of the epicenter, the discontinuity is observed on the eastern extension of the known active fault which may have branched northward. The surface fault ruptures are possibly to be seen on the ground.
The ground in the northern side of the crustal deformation area (cold-colored area) moves away from the satellite, while in the southern side (warm-colored area) the ground moves toward the satellite. (Fig. 1)
The ground in the northern side of the crustal deformation area (warm-colored area) moves toward the satellite, while in the southern side (cold-colored area) the ground moves away from the satellite. (Figs. 2, 3)

SAR Interferograms

Fig. 1 SAR interferogram[PNG: 1.30MB]

Fig. 2 Distribution of displacement in the line-of-sight direction between satellites and surface.
The analysis method (SBI (Split-bandwidth Interferometry) ) is based on Jiang et al. (2017).
Fault lines are based on Styron et al. (2010). [PNG: 1MB]

Fig. 3 SAR interferogram[PNG: 1MB]

Fig. 4 Map range

Fig. #	Date	Time (UTC)	Flight Dir.	Beam Dir.	Obs. Mode*1	Incidence Angle (around epicenter)	Bperp
1	2020-12-04 2021-06-04	5:29	Des.	Right	W-W (350km)	40°	173m
2,3	2020-05-25 2021-05-24	17:23	Asc.	Right	F-F (10m)	37°	-196m

*1 F: Stripmap (Fine), W: ScanSAR (Wide)
(cf. ALOS-2 Project / PALSAR-2 (JAXA))

Analysis by GSI from ALOS-2 data of JAXA.
These results were obtained through the activity of the SAR analysis working group of the Coordinating Committee for Earthquake Prediction.

The 2021 Qinghai Earthquake

Date-Time	May 21, 2021, 18:04(UTC)
Hypocenter Location	34.586°N, 98.255°E, Depth:10.0 km (USGS, as of May 25, 2021)
Magnitude	M=7.3 (USGS, as of May 25, 2021)

Satellite

ALOS-2 (Advanced Land Observing Satellite 2) launched by Japan Aerospace Exploration Agency on May 24, 2014

Copyrights and Credits

Contact

Geography and Crustal Dynamics Research Center
Crustal Deformation Research
MUNEKANE Hiroshi: Head of Division
Space Geodesy Research
KOBAYASHI Tomokazu: Head of Division