Manila, Aug 18 : A strong earthquake with a preliminary magnitude of 6.5 shook Masbate province in the Philippines on Tuesday, the Philippine Institute of Seismology and Volcanology (Phivolcs) said. No casualties and damage have been reported yet. The institute said the quake, which struck at around 8 a.m. local time, hit at a depth of 1 km, about 5 km southwest of Cataingan town of Masbate province in the Bicol region, Xinhua reported. The institute said the tremor was also felt in Mapanas town in Northern Samar province, Legazpi City in Albay province, Lezo town in Aklan province, Iloilo City, Capiz province and many provinces in the central Philippines. The institute said the quake, which was tectonic in origin, will trigger aftershocks. The Philippines has frequent seismic activity due to its location along the Pacific "Ring of Fire." /IANS