Earthquake depth is the estimated distance below the reference surface to the hypocenter, where rupture begins. The recent-event tracker displays depth in kilometers and can sort records from deepest to shallowest or the reverse.
Depth provides important scientific context, but it does not determine shaking or damage by itself. Magnitude, distance, rupture geometry, local geology, and construction must also be considered.
Shallow, intermediate, and deep earthquakes
The USGS commonly describes depths from 0 to 70 kilometers as shallow, 70 to 300 kilometers as intermediate, and 300 to 700 kilometers as deep. Intermediate and deep events occur mainly within descending slabs at subduction zones.
How earthquake depth is estimated
Networks compare seismic-wave arrival times across stations and solve for the origin time and three-dimensional location that best fits the observations. Depth may be less constrained when stations are distant or the network geometry is unfavorable, so early values can be revised.
Using depth in the live tracker
Sort by deepest to find events far below the surface or shallowest to inspect near-surface sources. Check the event type because blasts and other non-tectonic events may appear near zero depth. A slightly negative value can reflect reference surfaces or location uncertainty rather than a rupture in the air.