The 2018 Hualien (Taiwan) Earthquake: Crustal deformation detected by ALOS-2 data

A large earthquake (Mw 6.4, USGS) occurred around Hualien in Taiwan on February 6, 2018. Serious damage such as building collapse and many deaths has been reported. To measure the crustal deformation caused by the earthquake, we analyzed ALOS-2/PALSAR-2 data.

The results obtained from the data are summarized as follows.
 

• Large displacement has been detected along the Milun Fault and the northern part of the Lingding Fault with the length of ~15 km.
• Remarkably large uplift and northeastward displacement has been observed at the east side of the Milun Fault. At the southwestern part of the Milun Fault, subsidence has been observed.
• Discontinuity of the displacement is found along the Milun Fault through the center of Hualien city, which implies that surface ruptures may have appeared along the fault.

Fig. 1. 3D displacement derived from Figs. 3(b)(c) and 4(b)(c), (a) overview, (b) around Hualien city*.

Fig. 2. Displacement of (a) quasi vertical and (b) quasi EW components, derived from Figs. 3(a) and 4(a)*.

*These results may be affected by possible unwrapping errors (~12 cm ambiguity) at the east side of the Milun Fault in the used interferograms.


  Geometry of 2.5-D analysis

Fig. 3. Descending/Right (a) InSAR (overview), (b) InSAR (zoom), (c) azimuth offset (Pixel Offset method).
 

Fig. 4. Ascending/Right (a) InSAR (overview), (b) InSAR (zoom), (c) azimuth offset (Pixel Offset method).

Fig. 5. Descending/Left InSAR (a) overview, (b) zoom.
 

 

Fig. #	Date	Time (UTC)	Flight Dir.	Beam Dir.	Obs. Mode *1	Incidence Angle (Epicenter)	Bperp	KMZ
3	2017-06-18 2018-02-11	03:48	Des.	Right	F-F	40°	+223 m	1.4MB
4	2016-11-05 2018-02-10	15:50	Asc.	Right	H-H	28°	-159 m	1.5MB
5	2015-01-29 2018-02-08	04:22	Des.	Left	W-U	35°	-358 m	196KB

*1 F: Fine [10m], H: High Sensitive [6m], U: Ultrafine [3m], W: ScanSAR (Normal)
(cf. ALOS-2 Project / PALSAR-2 (JAXA))


Area of interest

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

Date-Time	February 6, 2018, 15:50 (UTC)
Hypocenter Location	24.131°N, 121.659°E, Depth: 17.0 km (USGS, as of February 16, 2018)
Magnitude	Mw=6.4 (USGS, as of February 16, 2018)

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

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YARAI Hiroshi : Head of Division
KOBAYASHI Tomokazu : Chief Researcher
MORISHITA Yu : Chief Researcher

• M 6.4 - 22km NNE of Hualian, Taiwan (USGS)