(FORTUNE Magazine) – In a pattern that dismally recalls what happened after 1992's Hurricane Andrew, the insurance industry has upped its estimates of how much January's Los Angeles earthquake will cost insurers. The first estimate, made just after the quake by American Insurance Services Group, a trade association, was $2.5 billion. But A.M. Best Co., the insurance rating firm, is now predicting $4 billion, a jump of 60%. And some insurance executives think it won't stop there, just as it didn't with Andrew. The estimates for that catastrophe, the costliest in U.S. history, went from an initial $7.8 billion to a mid-course $10.7 billion to an ultimate $15.5 billion -- a near doubling from start to finish. One California insurer, 20th Century (whose Woodland Hills headquarters were themselves damaged by the quake), has already doubled its estimate, going from $160 million to $325 million. Allstate has climbed from $350 million to $600 million, and State Farm from $600 million to $1 billion. The two publicly traded among these three, 20th Century and Allstate, have seen their stocks fall by around 20% since the quake. What has hit insurers is a double whammy: more claims than they expected and abnormally high costs to settle each. One reason is that this quake produced extraordinary vertical forces that were difficult for structures to withstand. But the initial underestimating may also reflect denial: Insurers didn't want to believe just how bad Andrew was, and they can't quite comprehend quakes that cost $4 billion or more. The toll from 1989's Loma Prieta quake in Northern California, after all, was short of $1 billion. But when catastrophes hit heavily populated areas like Los Angeles and the east coast of Florida, history doesn't count for much.

CHART: NOT AVAILABLE CREDIT: NO CREDIT CAPTION: HERE THEY GO AGAIN Estimated cost to insurance industry in billions