How many seismic stations are needed to determine the location of an earthquake's epicenter?

Ships can transit between the atlantic and pacific oceans using the canal.

The difference(s) between the grand canyon and valles marineris is/are: (a) the grand canyon was formed by water, but valles marineris was not. (a) valles marineris is much longer than the grand canyon. (c) valles marineris is much wider than the grand canyon. (d) valles marineris has large volcanoes near it. all of the above

What body of water is the second cataract of the nile river submerged under