Baku, July 28, AZERTAC An earthquake with a preliminary magnitude of 7.1 shook southwestern Japan on Tuesday, with tsunami advisories issued for the Ariake and Yatsushiro seas, Kyodo reported citing the weather agency said.The focus of the 4:27 p.m. quake was in Kumamoto Prefecture at a depth of about 10 kilometers, according to the Japan Meteorological Agency.