## 1 Introduction
### Rationale for Monitoring  
Volcanoes of the Lesser Antilles arc can erupt very violently. The fifth deadliest eruption in recorded history occurred in Martinique, where the eruption of Montagne Pelee killed around 29,000 inhabitants in 1902 [4]. Monitoring a suite of parameters is the only way to get a sense of the state of activity of the volcano and hence increase the chance to observe any changes in the volcanoes' behaviour. Even though some of the volcanoes of the chain seem rather calm or dormant, it is possible for them to re-awaken after extensive periods of quietness. The Soufriere Hills volcano of Montserrat, just 120 km SE of St. Eustatius, started to show signs of activity in 1995 after \(\sim\)350 years of dormancy [5]. The lack of baseline data prior to the onset of the surficial expression of volcanic activity was recognised as a hindrance when interpreting the data [6], and additional equipment was installed in the early days of the eruption [5]. Even though the eruption culminated in extensive pyroclastic flows that killed 19 people in 1997 [5], many casualties were avoided thanks to the timely evacuation of threatened areas [7]. The knowledge gained during the Soufriere Hills volcanic crisis stresses the importance of continuous monitoring of all volcanoes of the Lesser Antilles. Currently the extent of volcano monitoring networks varies considerably between the islands, as illustrated by Table 1.  
Pelean type activity was named by [PERSON] [8] after the 1902 eruption of Montagne Pelee in Martinique. The main hazard at Saba comes from so called \"Pelean\" type pyroclastic flows generated from an active dome [2]. As such domes are scattered island wide, the whole island is at high risk for this type of activity. On St. Eustatius, ancient pyroclastic flows were generated by column collapse from open crater eruptions similar to those of the 1902 and 1979 eruptions of La Soufriere at St. Vincent [9]. The threat scores for each volcano, calculated by multiplying the hazard and exposure factors following the method by [PERSON] [10] rank Mt. Scenery in the very high threat group and The Quill in the high threat group. These threat scores justify the importance of high level monitoring in near real-time on these islands. As of 1 January 2017, the population of the island of Saba reached 2010 people, and the population of St. Eustatius totalled 3250 people [11]. The expansion of the population at the islands observed over the past decade is expected to continue, implying that the number of people at risk, and the \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Island** & **Volcano** & **Agency** & **Seismic** & **cGNSS** & **Hot Springs** \\ \hline Saba & Mt. Scenery & KNMI & 4 BB & 0 & Sporadic, 79–08 (12) \\ St. Eustatius & The Quill & KNMI & 3 BB & 0 & no measurements \\ St. Maarten & KNMI & 1 BB & & & \\ St. Kitts & Mt. Liamuiga & TRN (SRC) & 3 SP, 1 BB, 1 SM & 1 & N/A \\ Nevis & Nevis Peak & TRN (SRC) & 3 SP & 1 & N/A \\ Montserrat & Soufriere Hills & MVO & 4 SP, 8 BB & 14 & monthly (3) \\ Guadeloupe & La Soufriere & IFGP & 7 SP, 8 BB & 8 & 4 multi-gaz, monthly (3) \\ Dominica & Morne aux Diables & TRN (SRC) & 4 SP, 4 BB, 4 SM, 3 sSP & 4 & yearly \\  & Morne Trois Piton & & & & \\  & Morne Patt & & & & \\ Martinique & Montagne Pelee & IFGP & 6 SP, 4 BB & 4 & 1 multi-gaz, monthly \\ St. Lucia & Qualibou & TRN (SRC)/UNAVCO & 4 SP, 3 BB, 4 sSM & 5 & N/A \\ St. Vincent & The Soufriere Volcano & TRN (SRC) & 2 SP, 1 BB, 2 SM, 4 sSP & 2 & N/A \\ Grenada & Kick em Jenny & TRN (SRC)/UNAVCO & 1 SP, 5 BB, 4 SM & 1 & N/A \\ Mt. St. Catherine & & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Operational volcano monitoring equipment according to the responsible agencies as of June 2017. BB: Broad Band seismometer, SP: Short Period seismometer, SM: Strong Motion seismometer, aSM: analogue Strong Motion seismometer, aSP: analogue Short Period seismometer, cGNSS: continuous Global Navigation Satellite System. For other abbreviations see the list at the end of the document.