According to the U.S. Geological Survey, a 5.4 magnitude quake struck close to Bacnotan Thursday morning.
The tremor jolted the area at 19:52 UTC (03:52 local time). It occurred at a depth of 35 km with the epicenter located approximately 38 km west-northwest of Bacnotan. Seismologists first reported it as a 5.3 event, but later upgraded it to 5.4.
Did you feel it?
Those who noticed the earthquake are encouraged to report it through the USGS Felt Report form. So far, the agency has collected 15 online responses from individuals indicating that they experienced the quake. The USGS DYFI report indicates that several people in and around the Manila area felt weak shaking during the tremor.

Impact and estimated losses
Green alert for shaking-related fatalities and economic losses. There is a low likelihood of casualties and damage. Recent earthquakes in this area have caused secondary hazards such as landslides and liquefaction that might have contributed to losses.
Structure information summary
Overall, the population in this region resides in structures that are a mix of vulnerable and earthquake resistant construction. The predominant vulnerable building types are unknown/miscellaneous types and heavy wood frame construction.
Source: The U.S. Geological Survey