Three key elements provide a basis for understanding magmatically driven phreatic eruptions: (1) recognizing magmatic involvement and magmatic input at an early stage of unrest, (2) identifying the timing, location, and rate of hydrothermal sealing, and (3) understanding the conditions which control vaporization of liquid water.
It is interesting to point out that, so far, similar VRP values have been recorded during the very early stages of unrest at Santa Ana volcano (from October 2004 to early January 2005, cf. Laiolo et al. 2017).
A volcano is in a stage of magmatic unrest if volcanic unrest is caused by the migration from a magma reservoir (left), which we are able to recognize as such.
In its place, Jurgen Flimm's grim update of prison walls, cellblocks and civil unrest: stage pictures that would fit credibly on the screens of television news.
If the cause of concern during a stage of volcanic unrest is the recognition of the migration from a magma reservoir (Figure 1), the volcano is in a stage of magmatic unrest.
Many volcanoes experience a prolonged stage of hydrothermal unrest, which can alter the hydraulic and rock mechanical properties leading to destabilization of a volcanic edifice.
The former are instigated by eruptive activity (e.g., Nevado del Ruíz 1985, Pierson et al. [1990]), and thus within a stage of magmatic unrest.
But from another point of view, the protests — which have been limited to a few hundred people — are a reminder of the early stages of past unrest in Myanmar, formerly called Burma.
Croatian authorities accused Serbia's president, Slobodan Milošević, of stage-managing the unrest in order to break Croatia's resolve to declare independence unless Yugoslavia was transformed into a loose confederation.
Their unprecedented weight made for unrest back stage.
