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A seismic gap along an accreting plate boundary : Example of the Djibouti Ridge, Afar, East Africa
Author(s) -
Ruegg JeanClaude,
Lépine JeanClaude
Publication year - 1983
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/gl010i005p00381
Subject(s) - seismology , geology , ridge , aftershock , magnitude (astronomy) , plate tectonics , lithosphere , extensional definition , tectonics , paleontology , physics , astronomy
A segment of the Gulf of Tadjoura (Djibouti, East‐Africa) accreting plate boundary, shows a period of quiescence in the seismic activity since 1974. This segment corresponds to the extension area of the aftershock activity that has occured after a cluster of magnitude 5.5 earthquakes in April 1973. From this example we propose that the seismic gap concept can be extended to moderate earthquakes occuring at extensional plate boundaries. The magnitude of the largest earthquakes at the spreading axis is limited by the size of the rupture length and by the strength of the brittle lithosphere. In the case of the Djibouti ridge recurrence time of 10‐20 years are found for earthquakes of about M =6.