Some small-scale rockfall activity started at approximately 22:50 on 28 April 2022 and continued until 1 May 2022. From the seismic data, these are located on the dome. Upon further investigation, the rockfalls have now been interpreted as heavy rainfall-induced. The rain gauge at Lees Yard recorded 18cm of rain from Thursday through to Saturday. By contrast, the rain gauge at MVO recorded just 4cm of rain in the first period.

Dr Adam Stinton mapped the location of the rain gauge in relation to the dome. The X’s equal the main areas for rockfall activity on the lava dome. LeesWx = rain gauge, MSS1 = spider seismic instrument.

Seismologist Roderick Stewart plotted the rainfall and rainfall counts. The top plot shows the cumulative rainfall at an MVO weather station from 28 April to 1 May 2022. The bottom plot shows the amplitude of the signal from an MVO seismic station close to the dome.

The small spikes in this data below the word “Rockfall” were generated by small rockfalls.

Source: MVO