@article{fdi:010067223,
  title = {{S}eafloor spreading event in western {G}ulf of {A}den during the {N}ovember 2010-{M}arch 2011 period captured by regional seismic networks : {E}vidence for diking events and interactions with a nascent transform zone},
  author = {{A}hmed, {A}. and {D}oubre, {C}. and {L}eroy, {S}. and {K}assim, {M}. and {K}eir, {D}. and {A}hmadine, {A}. and {P}errot, {J}. and {A}udin, {L}aurence and {V}ergne, {J}. and {N}ercessian, {N}. and {J}acques, {E}. and {K}hanbari, {K}. and {S}holan, {J}. and {R}olandone, {F}. and {A}l-{G}anad, {I}.},
  editor = {},
  language = {{ENG}},
  abstract = {{I}n {N}ovember 2010, intense seismic activity including 29 events with a magnitude above 5.0, started in the western part of the {G}ulf of {A}den, where the structure of the oceanic spreading ridge is characterized by a series of {N}115◦-trending slow-spreading segments set within an {EW}-trending rift. {U}sing signals recorded by permanent and temporary networks in {D}jibouti and {Y}emen, we located 1122 earthquakes, with a magnitude ranging from 2.1 to 5.6 from 2010 {N}ovember 1 to 2011 {M}arch 31. {B}y looking in detail at the space–time distribution of the overall seismicity, and both the frequency and the moment tensor of large earthquakes, we re-examine the chronology of this episode. {I}n addition, we also interpret the origin of the activity using high-resolution bathymetric data, as well as from observations of seafloor cable damage caused by high temperatures and lava flows. {T}he analysis allows us to identify distinct active areas. {F}irst, we interpret that this episode is mainly related to a diking event along a specific ridge segment, located at {E}044◦. {I}n light of previous diking episodes in nearby subaerial rift segments, for which field constraints and both seismic and geodetic data exist, we interpret the space–time evolution of the seismicity of the first few days. {M}igration of earthquakes suggests initial magma ascent below the segment centre. {T}his is followed by a southeastward dike propagation below the rift immediately followed by a northwestward dike propagation below the rift ending below the northern ridge wall. {T}he cumulative seismic moment associated with this sequence reaches 9.1 × 1017 {N}m, and taking into account a very low seismic versus geodetic moment, we estimate a horizontal opening of ∼0.58–2.9 m. {T}he seismic activity that followed occurred through several bursts of earthquakes aligned along the segment axis, which are interpreted as short dike intrusions implying fast replenishment of the crustal magma reservoir feeding the dikes. {O}ver the whole period, the opening is estimated to be ∼1.76–8.8 m across the segment. {A} striking feature of this episode is that the seismicity remained confined within one individual segment, whereas the adjacent en-echelon segments were totally quiescent, suggesting that the magma supply system of one segment is disconnected from those of the neighbouring segments. {S}econd, we identify activity induced by the first intrusion with epicentres aligned along an {N}035◦{E}-trending, ∼30 km long at the northwestern end of the active opening segment. {T}his group encompasses more than seven earthquakes with magnitude larger than 5.0, and with strike-slip focal mechanisms consistent with the faults identified in the bathymetry and the structural pattern of the area. {W}e propose that a transform fault is currently in formation which indicates an early stage of the ridge segmentation, at the locus of the trend change of the spreading ridge, which also corresponds to the boundary between a clear oceanic lithosphere and the zone of transform between continental and oceanic crust.},
  keywords = {{DJIBOUTI} ; {YEMEN} ; {ADEN} {GOLFE}},
  booktitle = {},
  journal = {{G}eophysical {J}ournal {I}nternational},
  volume = {205},
  numero = {2},
  pages = {1244--1266},
  ISSN = {1365-246{X}},
  year = {2016},
  DOI = {10.1093/gji/ggw068},
  URL = {https://www.documentation.ird.fr/hor/fdi:010067223},
}