If someone told you that workers' compensation helps workers in every situation when they suffer an injury on the job regardless of fault, that is mostly true. There are a few loopholes, and one them has to do with the term "Act of God."
It occurs when a workers' compensation insurer decides not to pay a claim, saying that the worker's injury stemmed from an Act of God - an unforeseen event that was impossible to plan for. Natural disasters such as earthquakes and tornadoes may fall under this category in some instances. However, even if an insurer denied your claim on this basis, there may be hope.
Other factors contributing to an injury
Earthquakes shake buildings and often cause people, furniture and debris to fall. If you sustained an injury during an earthquake and your insurer denied your claim due to an Act of God, it is worth taking a look at other aspects of the situation. For example, how structurally sound was the building you work in? If it could not have withstood the earthquake due to several construction defects, then that means the injuries you sustained could have been disproportionate. Thus, an Act of God denial does not seem to apply in your case.
Similarly, consider a hurricane injury. If your office has known that a hurricane was likely to hit your area but did not take reasonable precautions to keep workers safe, then an Act of God denial for your injury could be unfair and incorrect. You can successfully appeal Act of God denials, but they require good evidence and documentation.
The other loopholes
In case you are curious, the other loopholes besides Acts of God are if the employee was greatly intoxicated, if the injury involved illegal drugs (unless the employer provided them or the alcohol) or if the employee intended to hurt or kill others or himself/herself. Even in these areas, there is sometimes room to work with.