Given there are large aftershocks in both directions along the fault involved, it looks like this could have been a simultaneous bilateral rupture from a central epicenter (Like the 1906 San Franscisco Quake.)
Main quake was on the Laguna Salada Fault zone, and this appears like it may be a duplicate of an earthquake in 1892.
see my post 390, aftershocks on potentially three other fault zones
The prognosis?