OYO's water level meter captured "atmospheric vibrations" generated by the volcanic eruption

Do you know a water level meter?
The water level meter has various purposes, principles, and product types. We have a rich product lineup of "pressure-type" water level meters used for geological surveys, disaster monitoring, environmental monitoring, and so on.
One of our pressure-type water level meters (hereinafter referred to as "the Meter") measures the water pressure and converts it to the position of the water surface. The water pressure includes the air pressure which always fluctuates depending on various factors. To obtain the accurate water level, the Meter has a mechanism of measuring and eliminating the barometric pressure.
Here is a data that shows a sudden change in the air pressure captured by the Meter installed at our Tsukuba office in Ibaraki prefecture, around 8:30 pm on January 15.
This is due to the shock wave called the "atmospheric vibration" generated by the eruption of a large submarine volcano near Tonga. The Meter eliminates changes in the air pressure properly, and the water level data was not adversely affected even though the air vibration occurred without warning in the distant area.