WASHINGTON, May 22 (Reuters) - A magnitude 5.4 quake struck Nevada on Friday, close to the town of Helene, northeast of Las Vegas, the U.S. Geological Survey said. It said the quake, which was quite shallow at a depth of only 12 miles (19.4 km), was close to the border with Utah. The epicenter was located some 90 miles northeast (145 km) from Las Vegas. (Reporting by Sandra Maler; Editing by Eric Beech)