Most Significant Eruptions at Mt. Vesuvius

from: Scarth&Tanguy "Volcanoes of Europe"

Mt. Vesuvius is located at the southern end of a volcanically active area (Phlegraean Fields) that is located along a subduction zone where the Adriatic Micro-Plate sinks beneath the Tyrrhenian Sea (Western Mediterranean Sea). Mt. Vesuvius sits on old sedimentary rocks (Triassic dolomites, Jurassic limestones, Tertiary sandstones) and younger volcanic rocks (grey Campanian Tuffs). Mt. Vesuvius probably has the longest historical records of volcanic eruptions in the world. An eruption in 79 A.D. was recorded by Pliny the Younger in two letters to the Roman historian Tacitus. His uncle Pliny the Elder perished in an attempt to rescue friends ( click here to access an English translation.)

• A.D. 79


This eruption destroyed Pompeii, which was one of the largest towns in Campania, had a population of about 20,000 at the time, and Herculaneum, its population then 5000. The eruption was preceded by a larger earthquake in A.D. 62 and repairs were still going on when Mt. Vesuvius erupted. As suggested by Seneca, the earthquake is thought to be a precursory event to the eruption indicating an increase in magmatic pressure. Also 600 sheep were poisoned by "baleful air" (probably carbon dioxide). Earth tremors increased in frequency until initial explosions clear the conduit on the morning of August 24.


• 1pm August 24; initial eruptive column of gas reaching 20-30km high; lightning within the pine tree shaped cloud (Plinian Eruption column)
• ash, pumice and other ejecta fell on Pompeii as high as 1.4m during the next 7h, when most of the people probably fled from the town; villages on the western side of Vesuvius were still unharmed
• major change at 1am on August 25; less gases in the eruption column caused it to collapse several times, sending massive pyroclastic flows at 100km/h down the western valleys (e.g. Atrio del Cavallo), reaching Herculaneum in less than 4 min;
• most people had escaped (possibly by boat) but the few hundreds remaining were instantly killed at the beach (forensics of excavated skeletons indicate that death occurred within less than 1s)
• in the towns to the south (e.g. Pompeii and Stabiae) roofs collapsed under the weight of falling ash and debris (up to 7m thick), while torrential rain sent mudflows into Herculaneum (15-25m thick; roofs stayed intact)
• the 4th pyroclastic flow at 7:30am overwhelmed Pompeii, killing the remaining 2000 people;
• organic material vaporized in the immense heat (>500 deg C) leaving cavities behind; excavators filled these with plaster and the plaster casts now make gruesome exhibits of the dying people trying to protect themselves from the oncoming flows


• 1631 (considered a sub-Plinian eruption, i.e not as large as A.D. 79)


• had been dormant for 130 years before the eruption
• earthquakes in July and December
• wells without water in December
• lifestock seemed restless the night before the eruption
• December 16: explosions; ash cloud with lightning; fissures at the base of Mt. Vesuvius sending toxic fumes and lava down western valleys (i.e. Atrio del Cavallo)
• 40,000 people flee to Naples
• strong earthquakes during the night
• December 17, 7am: summit gets blown of in a big explosion;
• 9am: large mud flows destroy several villages and reach sea; earthquake causes 3 tsunamis
• 11am: lava flows destroy several towns to the west, town of Torre del Greco partially (see 1794)
• 'night' in Naples due to dense ash fall (up to 30 cm thick)
• December 18: activity ceased, leaving 4000 people dead


• 1779 (witnessed by Sir William Hamilton)


• lava fountain 4 km high


• 1794 (witnessed by Sir William Hamilton)


• fissure on the SW flank; lava flow to the sea destroying Torre del Greco
• at least 18 deaths


• 1906; April 4-22


• lava fountain 3 km high
• lava flows on SE flank destroying town of Boscotrecase; heavy damage in Ottaviano
• 218 deaths


• 1944; March 18-29 (last significant eruption)


• March 1: tremor activity (monitored at observatory) decreased; sporadic earthquakes occur instead; lowering of level in lava lake; production of lava decreases
• March 11: several explosions were central crater partially collapses
• March 17: activity ceased completely
• March 18, 2pm: seismic activity rises sharply
• 4pm: crater opens; heavy explosions; lava lake active for 3 days producing several lava flows down the slopes
• March 19: lava flows destruct the towns of S. Sebastiano and Massa
• March 20: lava fountains 2km high
• March 21: effusive activity ceases, giving way to explosive activity producing small pyroclastic flows
• March 22: collapse of conduit; explosions;
• March 23: ash falls to E
• March 26: production of white ash indicates final eruption phase
• 28 deaths


• Repose Period
Since 1631, repose periods have usually lasted for months or years after the final eruption. The calm since 1944 has now lasted so long that it far exceeds any period in modern times and may signal a complete change in the rhythm of activity at Vesuvius. In several scenarios it is thought that the 1944 eruption marks the end of a productive periods. Depending on which one, the next major eruption is thought to happen in a few decades or a few hundred years.