The weather agency said Monday it has observed over 180 earthquakes near the Tokara island chain in southwestern Japan over the weekend, urging residents to stay alert for a strong tremblor.A quake measuring 4 on the Japanese seismic intensity scale of 7 occurred twice Sunday and once early Monday on Akuseki Island in the island chain in Kagoshima Prefecture, the Japan Meteorological Agency said.Jolts with an epicenter near the island chain have been frequently observed since Saturday, according to the agency.Related coverage:Japan OKs 20 tril. yen plan for disaster resilient infrastructureREAD FULL ARTICLE