D35 Interferograms over Azores including SAR acquisitions provided annually, second delivery – TOUL

For the INSAR data analysis to date, we have used version 1.0 of the DIAPASON/PRISME software developed at the French Space Agency (CNES) and the associated open-source scripts DTOOLS developed by CNRS.DTP. The results from the INSAR analysis have been published. The primary conclusion in terms of the INSAR technique is that C-band SAR correlation breaks down in less than one year everywhere on Faial Island all but the northwest corner of Pico Island.

We have prepared a manuscript entitled, Time series analysis of SAR data applied to the study of the co-seismic deformation of the 9^th July 1998 Pico-Faial (Azores) earthquake” by C. M. CATITA^a, K.L. FEIGL^b, J. C. CATALÃO^a, J. M. MIRANDA^c, L. M. VICTOR^c, including the following institutions:

^a Laboratório de Tectonofísica e Tectónica Experimental, FCUL, Ed. C1, Piso 3, 1749-016 Lisboa, Portugal, Tel. +351 21 750 08 31, Fax. +351 21 750 00 42, cmcatita@fc.ul.pt

^b Centre National de la Recherche Scientifique, 14 Avenue E. Belin, 31400 Toulouse, France. Kurt.Feigl@cnes.fr

^c Centro de Geofísica da Universidade de Lisboa, FCUL, Ed. C8, 1749-016 Lisboa, Portugal

We plan to submit this manuscript for publication in Int. J. Rem. Sensing in March 2004. Here follows the abstract and three key figures:

The M_w 6.1 1998 Pico-Faial earthquake of 9 of July was one of the largest events recorded in the Azores (North Atlantic) in recent years. It generated significant co-seismic deformation that was captured by a GPS network on Faial Island. On the other islands, where no such networks were available, the co-seismic surface displacement field was heretofore unknown. To measure it on Pico Island, we analyse Synthetic Aperture Radar (SAR) images using interferometry. Our data set includes 18 images acquired by the ERS-1 and ERS-2 satellites in descending passes between June 1992 and November 2000. The interferograms computed from the available image pairs show poor correlation, particularly over the dense vegetated area of Faial Island and the flanks of Pico Volcano. However, a well-correlated fringe pattern remains over 33 months for barren parts of NW Pico Island. We analyse phase profiles across this fringe to distinguish the relative contributions of the co-seismic signal and the tropospheric noise, estimating a co-seismic step of 26.17 +/- 6 mm in range.

ORBIT	SENSOR	DATE	TRACK	FRAME	NORMAL BASELINE (m)	P (mb)	T (ºC)	U (%)	Wv (mb)
636	ERS2	04/06/1995	281	2835	-470	1026	21	75	14.6
1137	ERS2	09/07/1995	281	2835	-870	1018	21	95	17.3
2640	ERS2	22/10/1995	281	2835	546	1009	22	88	22
3141	ERS2	26/11/1995	281	2835	-865	1024	16	66	9.6
23315	ERS1	30/12/1995	281	2835	94	997	16	74	10.3
3642	ERS2	31/12/1995	281	2835	-159	995	13	72	10.1
17169	ERS2	02/08/1998	281	2835	-285	1028	26	63	24.6
18171	ERS2	11/10/1998	281	2835	0	1027	23	77	18.2
29193	ERS2	19/11/2000	281	2835	-623	1028	21	79	15.7
ORBIT	SENSOR	DATE	TRACK	FRAME	NORMAL BASELINE (m)	P (mb)	T (ºC)	U (%)	Wv (mb)
4607	ERS1	09/06/1992	52	2835	-32	1012	18	60	12
8714	ERS1	16/03/1993	52	2835	-186	1016	16	81	13.7
908	ERS2	23/06/1995	52	2835	-1060	1009	22	88	13.1
22585	ERS1	09/11/1995	52	2835	-34	1027	16	77	11.2
2912	ERS2	10/11/1995	52	2835	-274	1025	16	73	10
23086	ERS1	14/12/1995	52	2835	217	1021	16	63	11.7
3413	ERS2	15/12/1995	52	2835	-31	1015	16	71	9.5
16940	ERS2	17/07/1998	52	2835	-1221	1022	23	76	17.3
17942	ERS2	25/09/1998	52	2835	0	1018	23	73	18.9

Table 1- ERS SAR images, of tracks 52 and 281, acquired for this study. The normal baselines are computed considering the images 18171 (track 281) and 17942 (track 52) as reference. The meteorological parameters Temperature (T [ºC]), Humidity (U (%)) and Pressure (P [mb]) were acquired at FAIM station (Horta Island) and the Water Vapor (Wv [mb]) is computed from radiosonde data acquired at Lajes (Terceira Island), at 12 hours of local time of the image acquisition date.

Figure 1 – Observed and calculated differential co-seismic interferograms. One color fringe represents 28.3 mm of range change. Panels A through F: track 52, frame 2835; A: 4706-17942; B: 8714-17942; C: 22585-17942; D: 2912-17942; E: 23086-17942, F: 3413-17942. Panels G and H: track 281, frame 2835; G: 23315-18171, H: 3642-18171. Panel I and J: fringe pattern calculated from fault Model 1 and Model 2, respectively. The cross sections AA’ and BB’ represent the profiles extracted from the pre- and co-seismic interferograms.

Figure 2 – a) Estimated range change values per epoch. The mathematical model used to fit these values is represented by the Heaviside step function (red line); b) Observed data (black x-mark) and predicted values (red squares) found by least squares temporal adjustment.