why would it be difficult for scientist to locate the epicenter of an earthquake if they have seismic wave information from only two locations.

Because it is at least 3 locations that should be used to get an accurate location.

Explanation:

It would be difficult to get the location of the epicenter of an earthquake from just 2 locations because generally speaking when trying to locate the epicenter it is always advice able to use at least 3 locations to guarantee accuracy.