Members of the Philippine Air Force join representatives from the Philippine Institute of Volcanology and Seismology in an aerial inspection around Mayon Volcano. Feb. 9, 2018. Val Cuenca, ABS-CBN News

MANILA - Two solar panels were stolen from an earthquake monitoring observatory in Tabaco City, Albay, the Department of Science and Technology-Phivolcs said Thursday.

A crater glow was observed at the picturesque Mayon Volcano over the past 2 days, indicating that "remnant magma" from its last explosion in 2018 may be rising to shallow levels, Phivolcs said Wednesday.

On the same day, the 150-watts solar panels were discovered missing by Mayon Volcano Observatory personnel during their routine inspection and preventive maintenance service, the agency said in a statement.

"With loss of power supply, no data will be transmitted from this station and consequently will affect the monitoring of Mayon Volcano," it said.

The agency added that the law prohibits "unauthorized taking, stealing, keeping, or tampering of government risk reduction and preparedness equipment, accessories and similar facilities.

"The public is strongly encouraged to help in taking care of our monitoring instruments and to promptly report any untoward incidents," it said.

The volcano remains under alert level 2 or a "moderate level of unrest."