 Numerous sites running along the New River were examined including the twin reinforced concrete bridges in Brawley . Slumping of the foundations there resulted in severe damage , and occurred as a result of the October 15 main shock , though the Brawley earthquake 's epicenter was nearby . At the Imperial County Dump , several instances of ground failure were observed in sedimentary deposits near the top of and parallel to the river bank , and other cracks were found in that area that were determined to be the result of differential settling . Farther north at the entrance to the Del Rio Country Club , 30 cm ( 12 in ) scarplets were located west of Route 111 , but undisturbed Pleistocene sedimentary layers likely indicated that the scarps were the result of local slumping in the roadcut and not the result of surface faulting . A large pond had apparently formed near the KROP radio station 's antenna site where profound liquefaction and subsidence occurred in the river valley . Two weeks following the earthquake sand boils at the same location were still discharging water . 
