  On January 15, 2022, at 04:14:45 (UTC), the Hunga Tonga-Funga Ha'apai, a
submarine volcano in the Tongan archipelago in the southern Pacific Ocean,
erupted and generated global seismic, shock, and electromagnetic waves, which
also reached Japan, situated more than 8,000 km away. KAGRA is a gravitational
wave telescope located in an underground facility in Kamioka, Japan. It has a
wide variety of auxiliary sensors to monitor environmental disturbances which
obstruct observation of gravitational waves. The effects of the volcanic
eruption were observed by these environmental sensors both inside and outside
of the underground facility. In particular, the shock waves made it possible to
evaluate the transfer functions from the air pressure wave in the atmosphere to
the underground environmental disturbances (air pressure and seismic motion).
