The seismic activity density of a region is the ratio of the number of earthquakes during a given time span to the land area affected. A state had 424 earthquakes over a given time span and a land area of 71,300 square miles. What is the seismic activity density for this state? Round to the nearest ten thousandth, if necessary.

0.0046 earthquakes per square mile
0.0059 earthquakes per square mile
168.1604 earthquakes per square mile
179.0049 earthquakes per square mile