## 3 Results
### Eruptive Activity between 28 March and 1 April 2020
By midnight, the lava flow was no longer fed and, as soon as it stopped, the number of explosions per h gradually increased during the 29 March (Figure 3a). Poor visibility characterized most of 30 March between 07:00 and midnight, but from the images of SCT at 23:31 we could distinguish incandescent blocks that rolled over the NEC crater rim and down the SdF slope, signaling the start of another overflow. The number and size of the incandescent blocks rolling down the slope increased at 23:49, while two lava flows were spreading, one towards East and another towards North. The North flow was the longest and turned out to have the greater flux. The incandescent blocks detaching from the flow fronts accumulated along the coast and formed a hot talus that could be easily viewed during the early h of 31 March. At 01:46 and 01:49, two PDCs descended the SdF reaching the sea, and expanded as a cloud on the sea surface, followed by several other similar events, most of which are listed in Table 3. It is worth noting that the speed of the PDCs spreading on the sea surface was generally increasing from 6.9 m s\({}^{-1}\) to 23.3 m s\({}^{-1}\) between 01:50 and 02:51, and decreasing afterwards to 5.9 m s\({}^{-1}\) until 03:41. The measured distance that was travelled by the PDC on the sea surface from the coast varied between 108 and 165 m, with speeds between 4.4 and 23.3 m s\({}^{-1}\) (Table 3). Table 4 presents a list of several lava flows and PDCs that descended the SdF and reached the coast during 31 March. It shows the difference between the speed of the lava flows, from 2.8 to 5.2 m s\({}^{-1}\), and the PDCs, which displayed velocities that were between 12.9 and 40.3 m s\({}^{-1}\). Figure 3: _Cont._ \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Start Time (hh:mm:ss)** & **End Time (hh:mm:ss)** & **Distance on the Sea (m)** & **Speed (m s\({}^{-1}\))** \\ \hline
01:50:00.0 & 01:50:20.5 & 141 & 6.9 \\
02:35:25.5 & 02:35:50.0 & 108 & 4.4 \\
02:45:10.0 & 02:45:21.0 & 118 & 10.7 \\
02:48:36.5 & 02:48:47.5 & 120 & 10.9 \\
02:51:41.5 & 02:51:47.5 & 140 & 23.3 \\
02:54:15.5 & 02:54:27.0 & 140 & 12.2 \\
03:02:25.0 & 03:02:42.5 & 134 & 7.7 \\
03:06:23.0 & 03:06:40.0 & 165 & 9.7 \\
03:37:09.0 & 03:37:25.5 & 145 & 8.8 \\
03:39:07.5 & 03:39:22.0 & 141 & 9.7 \\
03:41:46.5 & 03:42:13.0 & 155 & 5.9 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: List of the pyroclastic density currents (PDCs) spreading on the sea surface on 31 March 2020, as detected from the SPCT camera. The start time indicates when the flow reached the coast, the end time when it reached the maximum distance out to sea. Figure 3: Comparative graphs of monitoring data collected between 28 March and 1 April 2020, with the two red rectangles displaying the duration of the two overflows from the NE crater rim occurred on 28 and 30–31 March. (**a**) Number of explosions per h detected from the thermal monitoring cameras SCT (red line) and SPCT (blue line) between 28 March and 1 April 2020. The parts with no data are caused by poor weather conditions with clouds obscuring the summit area; (**b**) Real Time Seismic Amplitude Monitoring (RSAM) of the STRE station (Figure 1) seismic signal (East–West component) filtered at a frequency \(>10\) Hz, calculated on 15-s windows); (**c**) GBInSAR NE190 cumulative displacement (positive values refer to the increasing distance between the sensor and the target area, representing the deflation of the summit area; (**d**) Standardized NEC area measured using GBInSAR NE400 power images (one image every four h; xn \(=\) xu u/\(\sigma\); where xn is the standardized data, xu is the original data, \(\mu\) is the mean and \(\sigma\) is the standard deviation of the time series); and, (**e**) Radiant heat flux estimated by HOTSAT using Moderate Resolution Imaging Spectroradiometer (MODIS) (blue dots), Sea and Land Surface Temperature Radiometer (SLSTR) (red dots), and Visible Infrared Imaging Radiometer Suite (VIIRS) (green dots) data from 28 March to 1 April 2020.