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Volumn 111, Issue , 2006, Pages

Kinematic models of plate boundary deformation in southwest Iceland derived from GPS observations

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EID: 84898855684     PISSN: 21699313     EISSN: 21699356     Source Type: Journal    
DOI: 10.1029/2005JB003907     Document Type: Article
Times cited : (67)

References (63)
  • 1
    • 84941788710 scopus 로고    scopus 로고
    • Successful prediction and warning of the 2000 eruption of Hekla based on seismicity and strain changes, Eos Trans
    • Fall Meet. Suppl.
    • Ágústsson, K., R. Stefánsson, A. T. Linde, P. Einarsson, I. S. Sacks, G. B. Gudmundsson, and B. Thorbjarnardóttir (2000), Successful prediction and warning of the 2000 eruption of Hekla based on seismicity and strain changes, Eos Trans. AGU, 81(48), Fall Meet. Suppl., Abstract V11B-30.
    • (2000) AGU , vol.81 , Issue.48
    • Ágústsson, K.1    Stefánsson, R.2    Linde, A.T.3    Einarsson, P.4    Sacks, I.S.5    Gudmundsson, G.B.6    Thorbjarnardóttir, B.7
  • 2
    • 0037058189 scopus 로고    scopus 로고
    • ITRF2000: A new release of the International Terrestrial Reference Frame for earth science applications
    • Altamimi, Z., P. Sillard, and C. Boucher (2002), ITRF2000: A new release of the International Terrestrial Reference Frame for earth science applications, J. Geophys. Res., 107(B10), 2214, doi: 10.1029/2001JB000561.
    • (2002) J. Geophys. Res. , vol.107 , Issue.B10 , pp. 2214
    • Altamimi, Z.1    Sillard, P.2    Boucher, C.3
  • 3
    • 33646361814 scopus 로고    scopus 로고
    • Evidences of instantaneous dynamic triggering during the seismic sequence of year 2000 in South Iceland
    • Antonioli, A., M. E. Belardinelli, A. Bizzarri, and K. S. Vogfjörd (2006), Evidences of instantaneous dynamic triggering during the seismic sequence of year 2000 in South Iceland, J. Geophys. Res., 111, B03302, doi: 10.1029/2005JB003935.
    • (2006) J. Geophys. Res. , vol.111 , pp. B03302
    • Antonioli, A.1    Belardinelli, M.E.2    Bizzarri, A.3    Vogfjörd, K.S.4
  • 4
    • 0028576211 scopus 로고
    • The 1989 Loma Prieta earthquake imaged from inversion of geodetic data
    • Árnadóttir, T., and P. Segall (1994), The 1989 Loma Prieta earthquake imaged from inversion of geodetic data, J. Geophys. Res., 99, 21, 835-21, 855.
    • (1994) J. Geophys. Res. , vol.99 , pp. 21835-21855
    • Árnadóttir, T.1    Segall, P.2
  • 7
  • 8
    • 10044229536 scopus 로고    scopus 로고
    • Coseismic stress changes and crustal deformation on the Reykjanes Peninsula due to triggered earthquakes on 17 June 2000 (2004)
    • Árnadóttir, T., H. Geirsson, and P. Einarsson (2004), Coseismic stress changes and crustal deformation on the Reykjanes Peninsula due to triggered earthquakes on 17 June 2000(2004), J. Geophys. Res., 109, B09307, doi: 10.1029/2004JB003130.
    • (2004) J. Geophys. Res. , vol.109 , pp. B09307
    • Árnadóttir, T.1    Geirsson, H.2    Einarsson, P.3
  • 9
    • 31644435252 scopus 로고    scopus 로고
    • Postseismic deformation following the June 2000 earthquake sequence in the south Iceland seismic zone
    • Árnadóttir, T., S. Jónsson, F. F. Pollitz, W. Jiang, and K. L. Feigl (2005), Postseismic deformation following the June 2000 earthquake sequence in the south Iceland seismic zone, J. Geophys. Res., 110, B12308, doi: 10.1029/2005JB003701.
    • (2005) J. Geophys. Res. , vol.110 , pp. B12308
    • Árnadóttir, T.1    Jónsson, S.2    Pollitz, F.F.3    Jiang, W.4    Feigl, K.L.5
  • 10
    • 0002010744 scopus 로고
    • The international GPS service for geodynamics: Development and start of official service on January 1, 1994
    • Beutler, G., I. I. Mueller, and R. E. Neilan (1994), The International GPS Service for Geodynamics: Development and start of official service on January 1, 1994, Bull. Geod., 68, 39-70.
    • (1994) Bull. Geod. , vol.68 , pp. 39-70
    • Beutler, G.1    Mueller, I.I.2    Neilan, R.E.3
  • 11
    • 0031423721 scopus 로고    scopus 로고
    • Southern California permanent GPS geodetic array: Continuous measurements of regional crustal deformation between the 1992 Landers and 1994 Northridge earthquakes
    • Bock, Y., et al. (1997), Southern California Permanent GPS Geodetic Array: Continuous measurements of regional crustal deformation between the 1992 Landers and 1994 Northridge earthquakes, J. Geophys. Res., 102, 18, 013-18, 033.
    • (1997) J. Geophys. Res. , vol.102 , pp. 18013-18033
    • Bock, Y.1
  • 12
    • 0032966935 scopus 로고    scopus 로고
    • Effects of superficial layers on coseismic displacements for a dip-slip fault and geophysical implications
    • Cattin, R., P. Briole, H. Lyon-Caen, P. Bernard, and P. Pinettes (1999), Effects of superficial layers on coseismic displacements for a dip-slip fault and geophysical implications, Geophys. J. Int., 137, 149-158.
    • (1999) Geophys. J. Int. , vol.137 , pp. 149-158
    • Cattin, R.1    Briole, P.2    Lyon-Caen, H.3    Bernard, P.4    Pinettes, P.5
  • 13
    • 0034943162 scopus 로고    scopus 로고
    • Estimating source parameters from deformation data, with an application to the March 1997 earthquake swarm off the Izu Peninsula, Japan
    • Cervelli, P., M. H. Murray, and P. Segall (2001), Estimating source parameters from deformation data, with an application to the March 1997 earthquake swarm off the Izu Peninsula, Japan, J. Geophys. Res., 106, 11, 217-11, 237.
    • (2001) J. Geophys. Res. , vol.106 , pp. 11217-11237
    • Cervelli, P.1    Murray, M.H.2    Segall, P.3
  • 14
    • 13644276188 scopus 로고    scopus 로고
    • Styles of surface rupture analysis accompanying the June 17 and 21, 2000 earthquakes in the south Iceland seismic zone
    • Clifton, A. E., and P. Einarsson (2005), Styles of surface rupture analysis accompanying the June 17 and 21, 2000 earthquakes in the south Iceland seismic zone, Tectonophysics, 396, 141-159.
    • (2005) Tectonophysics , vol.396 , pp. 141-159
    • Clifton, A.E.1    Einarsson, P.2
  • 17
    • 0028666276 scopus 로고
    • Effect of recent revisions to the geomagnetic reversal time scale on estimates of current plate motions
    • De Mets, C. G., R. G. Gordon, D. F. Argus, and S. Stein (1994), Effect of recent revisions to the geomagnetic reversal time scale on estimates of current plate motions, Geophys. Res. Lett., 21, 2191-2194.
    • (1994) Geophys. Res. Lett. , vol.21 , pp. 2191-2194
    • De Mets, C.G.1    Gordon, R.G.2    Argus, D.F.3    Stein, S.4
  • 18
    • 84964203940 scopus 로고
    • Bootstrap methods for standard errors, confidence intervals, and other measures of statistical accuracy
    • Efron, B., and R. Tibshirani (1986), Bootstrap methods for standard errors, confidence intervals, and other measures of statistical accuracy, Stat. Sci., 1, 54-77.
    • (1986) Stat. Sci. , vol.1 , pp. 54-77
    • Efron, B.1    Tibshirani, R.2
  • 19
    • 0026001531 scopus 로고
    • Earthquakes and present-day tectonism in Iceland
    • Einarsson, P. (1991), Earthquakes and present-day tectonism in Iceland, Tectonophysics, 189, 261-279.
    • (1991) Tectonophysics , vol.189 , pp. 261-279
    • Einarsson, P.1
  • 20
    • 0020344557 scopus 로고
    • Earthquake fractures in the districts Land and Rangárvellir in the south Iceland seismic zone
    • Einarsson, P., and J. Eiríksson (1982), Earthquake fractures in the districts Land and Rangárvellir in the south Iceland seismic zone, Jökull, 32, 113-120.
    • (1982) Jökull , vol.32 , pp. 113-120
    • Einarsson, P.1    Eiríksson, J.2
  • 21
    • 0002956478 scopus 로고
    • Earthquake epicenters 1982-1985 and volcanic systems in Iceland
    • edited by T. I. Sigfusson, Menningarsjodur, Reykjavík, Iceland
    • Einarsson, P., and K. Smundsson (1987), Earthquake epicenters 1982-1985 and volcanic systems in Iceland, in Í hlutarins edli, Map accompanying festschrift for T. Sigurgeirsson, edited by T. I. Sigfusson, Menningarsjodur, Reykjavík, Iceland.
    • (1987) Í Hlutarins Edli, Map Accompanying Festschrift for T. Sigurgeirsson
    • Einarsson, P.1    Smundsson, K.2
  • 23
    • 19244375818 scopus 로고
    • Space geodetic measurement of crustal deformation in central and southern California, 1984-1992
    • Feigl, K. L., et al. (1993), Space geodetic measurement of crustal deformation in central and southern California, 1984-1992, J. Geophys. Res., 98, 21, 677-21, 712.
    • (1993) J. Geophys. Res. , vol.98 , pp. 21677-21712
    • Feigl, K.L.1
  • 24
    • 0034518240 scopus 로고    scopus 로고
    • Crustal deformation near Hengill volcano, Iceland 1993-1998: Coupling between magmatic activity and faulting inferred from elastic modeling of satellite radar interferograms
    • Feigl, K. L., J. Gasperi, F. Sigmundsson, and A. Rigo (2000), Crustal deformation near Hengill volcano, Iceland 1993-1998: Coupling between magmatic activity and faulting inferred from elastic modeling of satellite radar interferograms, J. Geophys. Res., 105, 25, 655-25, 670.
    • (2000) J. Geophys. Res. , vol.105 , pp. 25655-25670
    • Feigl, K.L.1    Gasperi, J.2    Sigmundsson, F.3    Rigo, A.4
  • 27
    • 0025596491 scopus 로고
    • The mechanics of the south Iceland seismic zone
    • Hackman, M. C., G. C. P. King, and R. Bilham (1990), The mechanics of the south Iceland seismic zone, J. Geophys. Res., 95, 17, 339-17, 351.
    • (1990) J. Geophys. Res. , vol.95 , pp. 17339-17351
    • Hackman, M.C.1    King, G.C.P.2    Bilham, R.3
  • 29
    • 3142615729 scopus 로고
    • Geodesy by radio interferometry: The application of Kalman filtering to very long baseline interferometry data
    • Herring, T. A., J. L. Davis, and I. I. Shapiro (1990), Geodesy by radio interferometry: The application of Kalman filtering to very long baseline interferometry data, J. Geophys. Res., 95, 12, 561-12, 581.
    • (1990) J. Geophys. Res. , vol.95 , pp. 12561-12581
    • Herring, T.A.1    Davis, J.L.2    Shapiro, I.I.3
  • 30
    • 0037113622 scopus 로고    scopus 로고
    • Reconciling seismic and geodetic models of the 1989 Kilauea south flank earthquake
    • Hooper, A., P. Segall, K. Johnson, and J. Rubinstein (2002), Reconciling seismic and geodetic models of the 1989 Kilauea south flank earthquake, Geophys. Res. Lett., 29(22), 2062, doi: 10.1029/2002GL016156.
    • (2002) Geophys. Res. Lett. , vol.29 , Issue.22 , pp. 2062
    • Hooper, A.1    Segall, P.2    Johnson, K.3    Rubinstein, J.4
  • 31
    • 33646348347 scopus 로고    scopus 로고
    • Mapping subsurface faults in southwest Iceland using relatively located microearthquakes
    • Hjaltadóttir, S., K. S. Vogfjörd, and R. Slunga (2005), Mapping subsurface faults in southwest Iceland using relatively located microearthquakes, Geophys. Res. Abstr., 7, Abstract EGU05-A-06664.
    • (2005) Geophys. Res. Abstr. , vol.7
    • Hjaltadóttir, S.1    Vogfjörd, K.S.2    Slunga, R.3
  • 32
    • 0034902857 scopus 로고    scopus 로고
    • Crustal deformation at the oblique spreading Reykjanes Peninsula, SW Iceland: GPS measurements from 1993 to 1998
    • Hreinsdóttir, S., P. Einarsson, and F. Sigmundsson (2001), Crustal deformation at the oblique spreading Reykjanes Peninsula, SW Iceland: GPS measurements from 1993 to 1998, J. Geophys. Res., 106, 13, 803-13, 816.
    • (2001) J. Geophys. Res. , vol.106 , pp. 13803-13816
    • Hreinsdóttir, S.1    Einarsson, P.2    Sigmundsson, F.3
  • 35
  • 36
    • 0034629564 scopus 로고    scopus 로고
    • Global Positioning System constraints on plate kinematics and dynamics in the eastern Mediterranean and Caucasus
    • McClusky, S., et al. (2000), Global Positioning System constraints on plate kinematics and dynamics in the eastern Mediterranean and Caucasus, J. Geophys. Res., 105, 5695-5720.
    • (2000) J. Geophys. Res. , vol.105 , pp. 5695-5720
    • McClusky, S.1
  • 37
    • 0002511420 scopus 로고
    • Relations between the eruptions of various volcanoes and the deformation of the ground surfaces around them
    • Mogi, K. (1958), Relations between the eruptions of various volcanoes and the deformation of the ground surfaces around them, Bull. Earthquake Res. Inst. Univ. Tokyo, 36, 99-134.
    • (1958) Bull. Earthquake Res. Inst. Univ. Tokyo , vol.36 , pp. 99-134
    • Mogi, K.1
  • 38
    • 0027095145 scopus 로고
    • Internal deformation due to shear and tensile faults in a half-space
    • Okada, Y. (1992), Internal deformation due to shear and tensile faults in a half-space, Bull. Seismol. Soc. Am., 82, 1018-1040.
    • (1992) Bull. Seismol. Soc. Am. , vol.82 , pp. 1018-1040
    • Okada, Y.1
  • 39
    • 84954082351 scopus 로고    scopus 로고
    • Triggered fault slip on June 17, 2000 on the Reykjanes Peninsula, SW-Iceland captured by radar interferometry
    • doi:10.1029/2002GL015310
    • Pagli, C., Pedersen, R., Sigmundsson, F. & Feigl, K. (2003), Triggered seismicity on June 17, 2000 on Reykjanes Peninsula, SW-Iceland captured by radar interferometry, Geophys. Res. Lett., 30(6), 6, doi:10.1029/2002GL015310.
    • (2003) Geophysical Research Letters , vol.30 , Issue.6 , pp. 6
    • Pagli, C.1    Pedersen, R.2    Sigmundsson, F.3    Feigl, K.L.4
  • 43
    • 0000005724 scopus 로고
    • Geodetic determination of relative plate motion in central California
    • Savage, J. C., and R. O. Burford (1973), Geodetic determination of relative plate motion in central California, J. Geophys. Res., 78, 832-845.
    • (1973) J. Geophys. Res. , vol.78 , pp. 832-845
    • Savage, J.C.1    Burford, R.O.2
  • 45
    • 0000225581 scopus 로고
    • Fault zone models, heat flow, and the depth distribution of earthquakes in the continental crust of the continental United States
    • Sibson, R. H. (1982), Fault zone models, heat flow, and the depth distribution of earthquakes in the continental crust of the continental United States, Bull. Seismol. Soc. Am., 72, 151-163.
    • (1982) Bull. Seismol. Soc. Am. , vol.72 , pp. 151-163
    • Sibson, R.H.1
  • 46
    • 0022858963 scopus 로고
    • Earthquakes and rock deformation in crustal fault zone
    • Sibson, R. H. (1986), Earthquakes and rock deformation in crustal fault zone, Annu. Rev. Earth Planet. Sci., 14, 149-175.
    • (1986) Annu. Rev. Earth Planet. Sci. , vol.14 , pp. 149-175
    • Sibson, R.H.1
  • 47
    • 0038037767 scopus 로고    scopus 로고
    • REVEL: A model for Recent plate velocities from space geodesy
    • Sella, G. F., T. H. Dixon, and A. Mao (2002), REVEL: A model for Recent plate velocities from space geodesy, J. Geophys. Res., 107(B4), 2081, doi: 10.1029/2000JB000033.
    • (2002) J. Geophys. Res. , vol.107 , Issue.B4 , pp. 2081
    • Sella, G.F.1    Dixon, T.H.2    Mao, A.3
  • 48
    • 0027072004 scopus 로고
    • Glacio-isostatic crustal movements caused by historical volume change of the Vatnajökull ice cap, Iceland
    • Sigmundsson, F., and P. Einarsson (1992), Glacio-isostatic crustal movements caused by historical volume change of the Vatnajökull ice cap, Iceland, Geophys. Res. Lett., 19(21), 2123-2126.
    • (1992) Geophys. Res. Lett. , vol.19 , Issue.21 , pp. 2123-2126
    • Sigmundsson, F.1    Einarsson, P.2
  • 49
    • 0027037723 scopus 로고
    • Magma chamber deflation recorded by the Global Positioning System: The Hekla 1991 eruption
    • Sigmundsson, F., P. Einarsson, and R. Bilham (1992), Magma chamber deflation recorded by the Global Positioning System: The Hekla 1991 eruption, Geophys. Res. Lett., 19(14), 1483-1486.
    • (1992) Geophys. Res. Lett. , vol.19 , Issue.14 , pp. 1483-1486
    • Sigmundsson, F.1    Einarsson, P.2    Bilham, R.3
  • 50
    • 0028895352 scopus 로고
    • Rifttransform kinematics in south Iceland: Deformation from Global Positioning System measurements, 1986 and 1992
    • Sigmundsson, F., P. Einarsson, R. Bilham, and E. Sturkell (1995), Rifttransform kinematics in south Iceland: Deformation from Global Positioning System measurements, 1986 and 1992, J. Geophys. Res., 100, 6235-6248.
    • (1995) J. Geophys. Res. , vol.100 , pp. 6235-6248
    • Sigmundsson, F.1    Einarsson, P.2    Bilham, R.3    Sturkell, E.4
  • 51
    • 0031436456 scopus 로고    scopus 로고
    • The 1994-1995 seismicity and deformation at the Hengill triple junction, Iceland: Triggering of earthquakes by minor magma injection in a zone of horizontal shear stress
    • Sigmundsson, F., P. Einarsson, S. T. Rögnvaldsson, G. R. Foulger, K. M. Hodgkinsson, and G. Thorbergsson (1997), The 1994-1995 seismicity and deformation at the Hengill triple junction, Iceland: Triggering of earthquakes by minor magma injection in a zone of horizontal shear stress, J. Geophys. Res., 102, 15, 151-15, 161.
    • (1997) J. Geophys. Res. , vol.102 , pp. 15151-15161
    • Sigmundsson, F.1    Einarsson, P.2    Rögnvaldsson, S.T.3    Foulger, G.R.4    Hodgkinsson, K.M.5    Thorbergsson, G.6
  • 52
    • 29444445621 scopus 로고    scopus 로고
    • Seismic activity associated with the 2000 eruption of Hekla, Iceland
    • Soosalu, H., P. Einarsson, and B. Thorbjarnardóttir (2005), Seismic activity associated with the 2000 eruption of Hekla, Iceland, Bull. Volcanol., 68, 21-36, doi: 10.1007/s00445-005-0417-7.
    • (2005) Bull. Volcanol. , vol.68 , pp. 21-36
    • Soosalu, H.1    Einarsson, P.2    Thorbjarnardóttir, B.3
  • 55
    • 0028262554 scopus 로고
    • Strain accumulation 1986-1992 across the Reykjanes Peninsula plate boundary, Iceland, determined from GPS measurements
    • Sturkell, E., F. Sigmundsson, P. Einarsson, and R. Bilham (1994), Strain accumulation 1986-1992 across the Reykjanes Peninsula plate boundary, Iceland, determined from GPS measurements, Geophys. Res. Lett., 21, 125-128.
    • (1994) Geophys. Res. Lett. , vol.21 , pp. 125-128
    • Sturkell, E.1    Sigmundsson, F.2    Einarsson, P.3    Bilham, R.4
  • 56
    • 0344823694 scopus 로고    scopus 로고
    • Recent unrest and magma movements at Eyjafjallajäkull and Katla volcanoes, Iceland
    • Sturkell, E., F. Sigmundsson, and P. Einarsson (2003), Recent unrest and magma movements at Eyjafjallajäkull and Katla volcanoes, Iceland, J. Geophys. Res., 108(B8), 2369, doi: 10.1029/2001JB000917.
    • (2003) J. Geophys. Res. , vol.108 , Issue.B8 , pp. 2369
    • Sturkell, E.1    Sigmundsson, F.2    Einarsson, P.3
  • 57
    • 0036900573 scopus 로고    scopus 로고
    • Three dimensional imaging of the P- and S-wave velocity structure and earthquake locations beneath southwest Iceland
    • Tryggvason, A., S. T. Rögnvaldsson, and O. Flóvenz (2002), Three dimensional imaging of the P- and S-wave velocity structure and earthquake locations beneath southwest Iceland, Geophys. J. Int., 151, 848-866.
    • (2002) Geophys. J. Int. , vol.151 , pp. 848-866
    • Tryggvason, A.1    Rögnvaldsson, S.T.2    Flóvenz, O.3
  • 58
    • 0001729570 scopus 로고
    • Crustal earthquake instability in relation to the depth variation of frictional slip properties
    • Tse, S. T, and J. R. Rice (1986), Crustal earthquake instability in relation to the depth variation of frictional slip properties, J. Geophys. Res., 91, 9452-9472.
    • (1986) J. Geophys. Res. , vol.91 , pp. 9452-9472
    • Tse, S.T.1    Rice, J.R.2
  • 59
    • 0030621290 scopus 로고    scopus 로고
    • Crustal deformation from 1992 to 1995 at the Mid-Atlantic Ridge, southwest Iceland, mapped by satellite radar interferometry
    • Vadon, H., and F. Sigmundsson (1997), Crustal deformation from 1992 to 1995 at the Mid-Atlantic Ridge, southwest Iceland, mapped by satellite radar interferometry, Science, 275, 193-197.
    • (1997) Science , vol.275 , pp. 193-197
    • Vadon, H.1    Sigmundsson, F.2
  • 60
    • 38349186770 scopus 로고    scopus 로고
    • w = 6.5 earthquake in the south Iceland seismic zone: The first five mintues
    • w= 6.5 earthquake in the south Iceland seismic zone: The first five mintues, Geophys. Res. Abstr., 5, Abstract EAE03-A-11251.
    • (2003) Geophys. Res. Abstr. , vol.5
    • Vogfjörd, K.S.1
  • 61
    • 85041234462 scopus 로고    scopus 로고
    • The August 2003 earthquake swarm near Krisuvik: Fault map from aftershocks and GPS measurements (in Icelandic)
    • Geosci. Soc. of Iceland, Reykjavik
    • Vogfjörd, K. S., H. Geirsson, and E. Sturkell (2004), The August 2003 earthquake swarm near Krisuvik: Fault map from aftershocks and GPS measurements (in Icelandic), paper presented at Spring Meeting 2004, Geosci. Soc. of Iceland, Reykjavik.
    • (2004) Spring Meeting 2004
    • Vogfjörd, K.S.1    Geirsson, H.2    Sturkell, E.3
  • 62
    • 33846019053 scopus 로고    scopus 로고
    • Volcano-tectonic interaction in the Hengill region, Iceland during 1993-1998
    • Vogfjörd, K. S., S. Hjaltadóttir, and R. Slungay (2005), Volcano-tectonic interaction in the Hengill region, Iceland during 1993-1998, Geophys. Res. Abstr., 7, Abstract EGU05-J-09947.
    • (2005) Geophys. Res. Abstr. , vol.7
    • Vogfjörd, K.S.1    Hjaltadóttir, S.2    Slungay, R.3
  • 63
    • 0000456913 scopus 로고    scopus 로고
    • New, improved version of generic mapping tools released
    • 579
    • Wessel, P., and W. H. F. Smith (1998), New, improved version of generic mapping tools released, Eos Trans. AGU, 79, 47, 579.
    • (1998) Eos Trans. AGU , vol.79 , pp. 47
    • Wessel, P.1    Smith, W.H.F.2


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