Increasing spatial coverage in rough terrain and vegetated areas using InSAR optimized pixel selection: application to Tohoku, Japan

Figures & data

Figure 1. (a) Study areas, showing the SAR images and GPS stations, base map is a gray shade Digital Elevation Model (DEM), (b) Google earth image showing the vegetation cover.

Table 1. Details of InSAR stack

Master	Slave	No.	${\mathit{B}}_{\mathrm{\perp }}$ (m)	∆t (day)	Satellite/Sensor /Direction
21 November 2010	19 February 2011	1	–245	90	ENVISAT-ASAR C-band Single polarization (HH) Descending Critical Normal Baseline (2100 m.)
	21 March 2011	2	–438	120
	20 April 2011	3	–458	150
	20 May 2011	4	415	180
	19 June 2011	5	–556	210
19 February 2011	21 March 2011	6	−228	30
	20 April 2011	7	–218	60
	20 May 2011	8	244	90
	19 June 2011	9	–337	120
21 March 2011	20 April 2011	10	99	30
	20 May 2011	11	377	60
	19 June 2011	12	–127	90
20 April 2011	20 May 2011	13	295	30
	19 June 2011	14	–127	60
20 May 2011	19 June 2011	15	–416	30

Figure 2. Spatial coherence vs temporal correlation.

Figure 3. Methodology block diagram.

Figure 4. Atmospheric wet delay ($\mathit{ZWD}$) vs altitude.

Figure 5. Atmospheric correction $\left(\mathit{d}\mathit{SWD}\right)$ and DEM.

Figure 6. Analysis of Sendai region (a) TCPs, (b) TSPs first subset. (c) Phase temporal correlation. (d) Coseismic interferogram before applying GPS fringe reduction and (e) after, (f) the corresponding final unwrapped phase map.

Table 2. Pixels density and coverage index

Region	Pixel type	No. of pixels	Density (Pixel/km^2)	Coverage Index	Change rate (%)
Aomori	TCP	271,095	53.3	0.37	+ 61
	TSP (first subset)	87,561	17.2	0.98
Iwate	TCP	452,545	58.0	0.40	+ 59
	TSP (first subset)	136,117	17.4	0.99
Sendai	TCP	727,763	169.7	0.60	+ 39
	TSP (first subset)	173,211	40.4	0.99
Iwaki	TCP	1,739,378	134.3	0.75	+ 23
	TSP (first subset)	289,035	36.8	0.98
Chiba	TCP	1,954,660	440.8	0.98	+ 2
	TSP (first subset)	465,854	105.1	1.00
Mean					+ 36.8

Figure 7. InSAR stack structure.

Table 3. Number of temporal stable pixels final subset

Region	TSPs (final subset)	TSPs with coherence < 0.2	Change rate vs TCP (%)
Aomori	428,768	157,673	58.2
Iwate	772,483	319,938	70.7
Sendai	968,678	240,915	33.1
Iwaki	1,739,378	685,665	65.1
Chiba	2,438,949	484,289	24.8
Mean			50.38

Figure 8. TCPs and TSPs first subset in Aomori, Iwate, Iwaki, and Chiba regions.

Figure 9. Final deformation maps for study areas and DEM error.

Figure 10. Estimated InSAR deformations vs observed GPS deformations, (a) Iwate region, (b) Iwaki region, and (c) Chiba region.

Table 4. Statistical analysis of the accuracy check

Region	No. of GPS stations	Mean STD (mm)	Mean RMSE (mm)
Iwate	5	14.0	14.9
Iwaki	10	8.7	8.9
Chiba	15	9.4	10.4
Mean		10.7	11.4

Data availability statement

The data that support the findings of this study are openly available in Geospatial Information Authority of Japan (GSI) at [https://www.gsi.go.jp/ENGLISH/] and European Space Agency at [https://earth.esa.int/eogateway/].