Operational InSAR Volcano and Seismic Monitoring in Spain. First Results.

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TENERIFE ISLAND (CANARIES, SPAIN) UNREST,
2004-2006, STUDIED VIA INTEGRATED GEODETIC
OBSERVATIONS
J. Fernández1, A. G. Camacho1, P.J. Gonzalez1, S.
Samsonov2, J.F. Prieto3, K. F. Tiampo2, J.
Gottsmann4, G. Puglisi5, F. Guglielmino5, J.J.
Mallorquí6, L. Tunini1, V. Willert7, G.
Rodríguez-Velasco1, M. Charco1, D. Navarrete6,
S. Duque6, D. Carrasco8 1CSIC-UCM,Madrid,
Spain. 2UWO, London, Canada 3UPM, Madrid,
Sapin 4Univ. Bristol, UK 5INGV-Catania,
Italy 6UPC, Barcelona, Spain 7Univ. Darmstadt,
Germany 8INDRA Espacio, Madrid, Spain
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INTRODUCTION.
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Geographical Population Information
CANARY ISLANDS

• 1 of the 17 Spanish Regions

• Area 7.440 km2

• Population 1.5 million inhabitants

• Density 220 pers./km2

• Tourism rate 10 million of tourist/year

TENERIFE
National Average 71 pers./km2

• Area 2 .032 km2

• 48 of the area protected

• Population 777.000 inhabitants

• Density 327 pers./km2

• 150.000 hotel beds

(J. Bonnet, Garavolcan, 2006)
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HISTORICAL ERUPTIONS
(J. Bonnet, Garavolcan, 2006)
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TENERIFE

• Seismic Network
• (IGN)
• Permanent GPS networks (IGN, ITER)
• Geochemical network
• (ITER)
• Geodetic Network
• (IAG)
• Micro-gravity network
• (IAG, Univ. Bristol, IGN)

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SEISMIC ACTIVITY Seismicity in the Canary
Islands, at least, for the last 20 years was
concentrated in a seismic zone located between
the island of Tenerife and Gran Canaria, and
where a magnitud 5,2 earthquake shook the area in
1989. Mezcúa et al. (1992) pointed out that a
horizontal compressional stress regime in NW-SE
direction is present in the region which is
compatible with the tectonics in the northwestern
part of the African continent. But, an anomalous
one has been recorded since 2001 and more
patently marked up to April 2004, when the first
seismic swarm has been indicated a possible magma
movements at depth.
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Tenerife Island
Previous results, 1992-2000 obtained using ERS-1,
2 radar images (Fernández et al., 2002, 2005)
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GPS CAMPAIGNS 2000 AUGUST (Global
Network) 2001 JULY 2002 JULY 2004 MAY 2005
JULY (Global Network) 2006 JANUARY (Global
Network) 2004-2006 campaigns were carried out
as a response to the seismic crisis.
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Differential interferogram of Tenerife, processed
with September 7, 2003 and March 20, 2005
ascending images.
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    2004/06/11-2005/09/09 DESCENDING  
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TENERIFE. DInSAR-GPS INTEGRATION.
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DInSAR-GPS OPTIMIZATION

• Ordinary kriging interpolation method was used to
  calculate initial continuous velocity maps and
  corresponding errors with the same geocoding and
  resolution (3 sec) as differential InSAR
  interferograms.
• 19 SAR scenes were processed for Tenerife but
  most of them had large decorrelation areas.
• Only 3 interferograms were sucessfully unwrapped
  for the whole island (in ddmmyy format)
  ascending 070903-130604 (A1), 130205-290106 (A2),
  and descending 110704-181105 (D1).
• Errors due to decorrelation and to incorrect
  topography estimation were calculated and
  combined together and then used as weighting
  parameters for the optimization.

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More than 200000x3600000 (!) data
values useful for interpretation Error
estimation for each displacement component
from 7x321, 8x324, or 18x354 data values
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MAIN PROBLEM Atmospheric errors. We are working
with single Interferograms and No corrections has
been applied. We consider a linear
relation between atmospheric errors and
geographical coordinates and perfom a linear
regresion.
20Jul93-13Jun97 B? 95 m
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INTERPRETATION OF DInSAR-GPS INTEGRATED
DEFORMATION FIELDS.
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• FIRST INVERSION RESULTS
• Strategy
• to try/compare with the cases which give better
  results using only gps and/or micro-gravity data
• to consider cases from one to many sources and to
  study what sources appear usually-always
• to consider different time period (2002-2004,
  2004-2005, 2005-2006,)
• to consider plane surface and real surface
  topography
• We use Random Search inversion technique (Camacho
  et al., 2007), and consider elastic media,
  spherical point sources, dikes and faults

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GPS GPSDInSAR GPSDInSARAt.C. GPSDInSAR
(AD) GPSDInSAR (AD) At.C.
PR3 Intensity gt 0
PR3 Intensity lt 0
Mass gt 0
Mass lt 0
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2002-2004
GPS GPS DInSAR GPS DInSAR At.C.
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2004-2005
GPS GPS DInSAR GPS DInSAR At.C. GPS DInSAR
(AD) GPS DInSAR (AD) At.C.
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2005-2006
GPS GPS DInSAR GPS DInSAR At.C.
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TENERIFE. FIRST CONCLUSIONS.
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• From the GPS campaigns observation we have
  detected deformation in several areas in the
  island, sometime with changes from subsidence to
  elevation or vice versa.
• Using classical DInSAR, we have also detected
  displacement at the same areas.
• Many of the epicenters of located seismicity are
  situated very close to the deformation zones.
• 4) Studing the Permanent GPS observation carried
  out in Tenerife we have detected some small
  deformations including slow temporal evolution
  and fast short period variations. That
  displacements look to be connected with the
  seismic activity recorded in the island for the
  same period (Fernández et al., 2005, 2006).

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• 5) We have determined 3D displacement field
  integrating GPS and DInSAR data.
• Not corrected atmospheric errors has been
  estimated as geographical location dependent with
  a linear regression.
• 3D displacement data has been inverted using
  Random Search inversion methodology (Gottsmann et
  al., 2006 Camacho et al., 2007).
• The inversions give as results sources of
  deformation chaging with time their horizontal
  position, depth, radius, pressure and mass
  values.
• The most consistent results are obtained with the
  integrated data corrected from atmospheric
  artifacts.

• Camacho, A. G., Fernández, J., Charco, C.,
  Tiampo, K.F. and Jentzsch, G., 2007.
  Interpretation of 1992-1994 gravity changes
  around Mayon volcano, Philippines, using point
  sources. Pure and applied geophysics (Pageoph),
  164/2. (In press)
• Gottsmann, J., Camacho, A.G., Tiampo, K.F.,
  Fernández, J., 2006. Spatio-temporal variations
  in vertical gravity gradients at the Campi
  Flegrei caldera (Italy) A case for source
  multiplicity during unrest. Geophysical Journal
  International, 167, 1089-1096.

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10) Now we are working in the inversion of
the 3D displacement data using GA technique
integration of micro-gravity data geological
interpretation of the inversion results jointly
with all the available information comparison
with previous interpretations (Gottsmann et
al., 2006 Almendros et al., 2007).

• Gottsmann, J., Wooller, J., Martí, J., Fernández,
  J., Camacho, A., González, P., García, A., Rymer,
  H., 2006. New evidence for the reawakening of
  Teide volcano. Geophysical Research Letters, 33,
  L20311, doi10.1029/2006GL027523.
• Almendros, J., Ibañez, J.M., Carmona, E.,
  Zandomeneghi, D., 2007. Array analyses of
  volcanic earthquakes and tremors recorded at Las
  Cañadas caldera (Tenerife Island, Spain) during
  the 2004 seismic activation of Teide volcano.
  Journal of Volcanology and Geothermal Research.