It depends on the severity of the damage. Generally, however, it costs millions of dollars to repair even minor damage caused by an earthquake. For example, here in California, it is estimated that it will cost around $4 billion to repair the damage from the recent earthquakes. This includes both structural and non-structural damage. And that's just for repairing what's been damaged thus far - it doesn't include any future damages that may occur as a result of continuing seismic activity.

It depends on the severity of the damage. Generally, it costs more to repair damage caused by an earthquake than it does to prevent that damage from happening in the first place. The most effective way to prevent earthquake damage is through structural reinforcement of buildings and other infrastructure. This can be expensive, but it's a lot cheaper than repairing the damage after an earthquake has occurred. In some cases, the cost of repairing earthquake-related damage can be catastrophic. For example, the 2011 Tohoku earthquake in Japan caused more than $200 billion in damages, and the cleanup and reconstruction efforts are still ongoing years later.