Because the shock occurred from the Red Sea Rift , it was described by Langer et al. as a " plate marginal " , rather than an intraplate event . Analysis of the source parameters revealed that the main shock was a complex normal faulting event , and consisted of two equal sized shocks , separated by about 12 seconds . It was compared to the 1983 Coalinga and 1984 Morgan Hill earthquakes , both of which were events in California which had similar dual shock characteristics
1983 Coalinga
1983 Coalinga earthquake
1982 North Yemen earthquake