I got mine done by Nick too for our cafe . Always on time and does things perfectly ! <| sep |> Depth of earthquakes is difficult to determine , especially if you don ' t have any nearby seismometers . Often depths have error bars of a few kilometers . If an agency cannot determine the depth then they fix it at a constant in their catalog . For USGS that is 10 km , but I think it used to be 33 km a while back so you might see a peak there too in earlier years . If you look at the event page it will say FIXED if it is an unknown depth . It isn ' t likely that 10 km is far off from the truth because deeper earthquakes have much clearer depth phases than anything ~ 20 km and shallower , provided the earthquake is large enough to be recorded above the background noise at a station .