The default for unknown depth used to be 200 km, years ago. I guess someone figured out that the earth's crust is thinner than that in spots, which would mean the quake was starting down in the magma layer. Maybe it can, or we don't understand enough about how the movement of magma affects the top.
10 km is the standard depth the USGS reports if they don't know.
Thanks, I did not know that.
The default for unknown depth used to be 200 km, years ago. I guess someone figured out that the earth's crust is thinner than that in spots, which would mean the quake was starting down in the magma layer. Maybe it can, or we don't understand enough about how the movement of magma affects the top.