LEGAZPI CITY -- Another earthquake briefly shook the Bicol region Wednesday evening, Philippine Institute of Volcanology and Seismology (Phivolcs) officials based at the Ligñon Hill observatory here said Thursday.

Senior science research analyst Alex Baloloy reported that the epicenter of the 5.1-magnitude earthquake, which occurred at 9:18 p.m., was located 49 kilometers northeast of Sorsogon province, which registered at Intensity 5.

Intensity 4 and Intensity 3 were felt in different areas in neighboring province Albay.

Data from the United States Geological Survey (USGS) website showed that the quake reached 65 kilometers East-Southeast of Legazpi City, Albay; 105 km Northeast of Masbate province; 105 km North-Northwest of Calbayog, Samar; and 405 km East-Southeast of Metro Manila.

Bicol has been subjected to earthquakes since a 5.1-magnitude earthquake last Friday, followed by aftershocks on Saturday morning, Sunday afternoon, and Monday morning.

Phivolcs officials said these quakes were tectonic in nature and were not related to the recent abnormal behavior of Mayon Volcano, which spewed a 200-meter ash column on August 10.