  The accurate and automated determination of earthquake locations is still a
challenging endeavor. However, such information is critical for monitoring
seismic activity and assessing potential hazards in real time. Recently, a
convolutional neural network was applied to detect earthquakes from
single-station waveforms and approximately map events across several large
surface areas. In this study, we locate 194 earthquakes induced during oil and
gas operations in Oklahoma, USA, within an error range of approximately 4.9 km
on average to the epicenter and 1.0 km to the depth in catalogs with data from
30 network stations by applying the fully convolutional network. The network is
trained by 1,013 historic events, and the output is a 3D volume of the event
location probability in the Earth. The trained system requires approximately
one hundredth of a second to locate an event without the need for any velocity
model or human interference.
