1. A method for locating a microseismic event in a subsurface formation, comprising: receiving a microseismic signal at a detector; obtaining a velocity model representative of the subsurface formation, the velocity model comprising multiple velocity layers; estimating, for each of the multiple velocity layers in the subsurface formation, a microseismic event location and a microseismic event origin time; and selecting one of the estimated locations and times using a parameter of the microseismic signal received at the detector.