Twenty-five years of geodetic measurements along the Tadjoura-Asal rift system, Djibouti, East Africa | INSTITUT DE PHYSIQUE DU GLOBE DE PARIS

Twitter

Aller au compte twitter

  Twenty-five years of geodetic measurements along the Tadjoura-Asal rift system, Djibouti, East Africa

Type de publication:

Journal Article

Source:

Journal of Geophysical Research-Solid Earth, Volume 112, Ticket B6, p.12 (2007)

ISBN:

0148-0227

URL:

http://www.agu.org/

Mots-clés:

RIFT; PROPAGATION; KINEMATICS; MOTIONS

Résumé:

Since most of Tadjoura-Asal rift system sits on dry land in the Afar depression near the triple junction between the Arabia, Somalia, and Nubia plates, it is an ideal natural laboratory for studying rifting processes. We analyze these processes in light of a time series of geodetic measurements from 1978 through 2003. The surveys used triangulation (1973), trilateration (1973, 1979, and 1981-1986), leveling (1973, 1979, 1984-1985, and 2000), and the Global Positioning System (GPS, in 1991, 1993, 1995, 1997, 1999, 2001, and 2003). A network of about 30 GPS sites covers the Republic of Djibouti. Additional points were also measured in Yemen and Ethiopia. Stations lying in the Danakil block have almost the same velocity as Arabian plate, indicating that opening near the southern tip of the Red Sea is almost totally accommodated in the Afar depression. Inside Djibouti, the Asal-Ghoubbet rift system accommodates 16 +/- 1 mm/yr of opening perpendicular to the rift axis and exhibits a pronounced asymmetry with essentially null deformation on its southwestern side and significant deformation on its northeastern side. This rate, slightly higher than the large-scale Arabia-Somalia motion (13 +/- 1 mm/yr), suggests transient variations associated with relaxation processes following the Asal-Ghoubbet seismovolcanic sequence of 1978. Inside the rift, the deformation pattern exhibits a clear two-dimensional pattern. Along the rift axis, the rate decreases to the northwest, suggesting propagation in the same direction. Perpendicular to the rift axis, the focus of the opening is clearly shifted to the northeast, relative to the topographic rift axis, in the "Petit Rift," a rift-in-rift structure, containing most of the active faults and the seismicity. Vertical motions, measured by differential leveling, show the same asymmetric pattern with a bulge of the northeastern shoulder. Although the inner floor of the rift is subsiding with respect to the shoulders, all sites within the rift system show uplift at rates varying from 0 to 10 mm/yr with respect to a far-field reference outside the rift.

Notes:

J. Geophys. Res.-Solid EarthISI Document Delivery No.: 182XOTimes Cited: 0Cited Reference Count: 43Cited References:ABDALLAH A, 1979, NATURE, V282, P17ACTON GD, 1991, TECTONICS, V10, P501ALTAMIMI Z, 2002, J GEOPHYS RES-SOL EA, V107, ARTN 2214ASFAW LM, 1992, NATURE, V357, P447BALLU V, 2003, EARTH PLANET SC LETT, V208, P41, DOI10.1016/S0012-821X(03)00002-5BESSE J, 1991, J GEOPHYS RES-SOLID, V96, P4029BEUTLER GJ, 1993, IGS WORKSH P 1993 IG, P20CATTIN R, 2005, EARTH PLANET SC LETT, V239, P352, DOI10.1016/j.epsl.2005.07.028CHU DH, 1999, NATURE, V398, P64COURTILLOT V, 1980, EARTH PLANET SC LETT, V47, P144DAUTEUIL O, 2001, TECTONOPHYSICS, V332, P423DECHABALIER JB, 1994, SCIENCE, V265, P1677DEMETS C, 1990, GEOPHYS J INT, V101, P425DEMETS C, 1994, GEOPHYS RES LETT, V21, P2191DOUBRE C, 2005, EOS T AGU, V86FERNANDES RMS, 2003, GEOPHYS RES LETT, V30, ARTN 1828FOULGER GR, 1992, NATURE, V358, P488HERRING TA, 1990, J GEOPHYS RES-SOLID, V95, P12561HUCHON P, 1991, ANN TECTONICAE, V5, P141JESTIN F, 1994, GEOPHYS J INT, V116, P637KING RW, 2000, DOCUMENTATION GAMITLEDAIN AY, 1979, B SOC GEOL FR, V7, P817MANIGHETTI I, 1997, J GEOPHYS RES-SOL EA, V102, P2681MANIGHETTI I, 1998, J GEOPHYS RES-SOL EA, V103, P4947MANIGHETTI I, 2001, J GEOPHYS RES-SOL EA, V106, P13613MANIGHETTI I, 2001, J GEOPHYS RES-SOL EA, V106, P13667MCCLUSKY S, 2000, J GEOPHYS RES-SOL EA, V105, P5695MCCLUSKY S, 2003, GEOPHYS J INT, V155, P126NEILAN R, 1995, JPL PUBL, V9518, P25RUEGG JC, 1979, GEOPHYS RES LETT, V6, P817RUEGG JC, 1987, GEOPHYS RES LETT, V14, P745RUEGG JC, 1990, CR ACAD SCI II-MEC P, V310, P1687RUEGG JC, 1993, GEOPHYS RES LETT, V20, P1899SELLA GF, 2002, J GEOPHYS RES-SOL EA, V107, ARTN 2081SICHLER B, 1980, B SOC GEOL FR, V22, P925SIGMUNDSSON F, 1992, GEOPHYS RES LETT, V19, P1483SIGMUNDSSON F, 2006, ICELAND GEODYNAMICSSOURIOT T, 1992, GEOLOGY, V20, P911STEIN RS, 1991, J GEOPHYS RES-SOLID, V96, P21789TAPPONNIER P, 1990, GEOPHYS RES LETT, V17, P1VERNANT P, 2004, GEOPHYS J INT, V157, P381, DOI10.1111/j.1365-246X.2004.02222.xVIGNY C, 2006, J GEOPHYS RES-SOL EA, V111, ARTN B02402WALPOLE SC, 1999, PAC CONSERV BIOL, V5, P28