[1] Fogo volcano, Cape Verde Islands, erupted in April 1995 after 43 years of dormancy. About 46 10 m of lava erupted during 7.5 weeks from vents on the SW flank of Pico do Fogo into Cha das Caldeiras. Interferograms obtained from 1993–1998 ERS SAR data show ground deformation due to the feeder dike but lack evidence for any volcano-wide deformation related to volume changes of a shallow magma ...

The rocky innards of the Earth locally melt to produce magma, which sometimes erupts as cataclysmic explosions. The energy released by these eruptions is matched only by that of large meteorite impacts. Whether large pools of magma generate huge volcanic eruptions, whose volume and duration can have global consequences for humanity, or solidify slowly within the Earth’s crust to form plutons (b...

Magma viscosity is strongly temperature-dependent. When hot magma flows in a conduit, heat is lost through the walls and the temperature decreases along the flow causing a viscosity increase. For particular values of the controlling parameters the steady-flow regime in a conduit shows two stable solutions belonging either to the slow or to the fast branch. As a consequence, this system may show...

Two volcanic eruptions in the Sumatra-Andaman arc that followed the disastrous M 9.3 earthquake of 26 December 2004 raise the question of whether these eruptions were triggered by the earthquake. Here we present new evidence to suggest that earthquake-induced decompression of the volcano magma systems leads to such eruptions. Numerical modeling reveals that other megathrust earthquakes induced ...

Silicic volcanic eruptions pose considerable hazards, yet the processes leading to these eruptions remain poorly known. A missing link is knowledge of the thermal history of magma feeding such eruptions, which largely controls crystallinity and therefore eruptability. We have determined the thermal history of individual zircon crystals from an eruption of the Taupo Volcanic Zone, New Zealand. R...

Phonolitic eruptions can erupt either effusively or explosively, and in some cases develop highly energetic events such as caldera-forming eruptions. However, the mechanisms that control the eruptive behaviour of such compositions are not well understood. By combining pre-eruptive data of well studied phonolitic eruptions we show that the explosive-effusive style of the phonolitic magma is cont...

The volcanic island of Surtsey (Vestmannaeyjar, Iceland) is the product of a 3.5-year-long eruption that began in November 1963. Observations of magma-water interaction during pyroclastic episodes made Surtsey the type example of shallow-to-emergent phreatomagmatic eruptions. Here, in part to mark the 50(th) anniversary of this canonical eruption, we present previously unpublished major-element...

Submarine pyroclastic eruptions at depths greater than a few hundred meters are generally considered to be rare or absent because the pressure of the overlying water column is sufficient to suppress juvenile gas exsolution so that magmatic disruption and pyroclastic activity do not occur. Consideration of detailed models of the ascent and eruption of magma in a range of sea floor environments s...

Introduction: Understanding the Moon's thermal and magmatic evolution entails understanding the origin of the earliest crust, in particular whether it formed from a magma ocean [1]. The energy of late stage planet-building impacts would be at least sufficient to form magma oceans and possibly enough to melt whole planets [2]. The solidification history of the magma ocean will place constraints ...

Volcanic eruptions are one of the World’s largest sources of hazards. This chapter reviews the main concepts of modern volcanological research, which is aimed at understanding how volcanoes work and how to mitigate the risk. The article starts by describing what volcanoes are, and how they are shaped by volcanic eruptions. The main mechanisms for magma formation and migration are then reviewed,...