Earthquake depth–origin-time trade-off
= Earthquake depth–origin-time trade-off
For surface stations at similar distances, the travel-time <derivatives> with respect to depth can be small or nearly equal. Their arrival-time shifts are then difficult to distinguish from a common change in <earthquake origin time>. A deeper source can be paired with an earlier origin. Nearby stations, broad distance coverage, and depth-sensitive phases help separate the two parameters.