An earthquake measuring 6.1 on the Richter scale struck Surigao del Sur province in the southern Philippines on Monday, authorities said. 

The Philippine Institute of Seismology and Volcanology (Phivolcs) said the offshore quake, which struck at 6.13 a.m., hit at a depth of 77 km, about 66 km northeast of Bayabas town on Mindanao island, reports Xinhua news agency.

The tremor was also felt in Surigao City in Surigao del Norte province and Gingoog City in Misamis Oriental province, Phivolcs added. The institute said the quake, which was tectonic in origin, will cause no damage but aftershocks are expected. The Philippines has frequent seismic activity due to its location along the Pacific "Ring of Fire".