**2. Short notes on the stratigraphy of Somma-Vesuvius in the last 40 ka BP**

The volcanic stratigraphy has been studied in detail in the last 40 ka BP [7]. Before this age, the volcano was looking like the Fuji volcano in Japan today (**Figure 1**). This analogy can be a best guess of the Somma volcano before 40 ka BP. The eruptive history of Somma volcano can be studied only on the Somma Caldera wall, which is poorly studied. Today, the volcano called Somma-Vesuvius volcano looks like the one shown in **Figure 2**. The aerial photo shows clearly the two morphologic characteristics: Somma caldera and Vesuvius cone nested into the

**Figure 1.** *Fujiyama volcano, Japan (taken from the Web).*

**83**

**Figure 4.**

**Figure 3.**

*Somma caldera seen from North to West.*

*The Somma-Vesuvius Activity with a Focus to the AD 79 Eruption: Hazard and Risk*

caldera. The Somma caldera is well exposed and looking from the North side (from Pollena town); the Vesuvius nested cone is hidden (**Figure 3**). Somma volcano should have been around 2000–2500 m high extrapolating from Somma Caldera, much higher than actual altitude of Vesuvius cone (Rolandi, unpublished data) [8]. The analysis of the eruptive history of Somma-Vesuvius (**Figure 4**) reveals the recurrence of highly explosive events followed by repose periods, during some of which low (2-3-4) VEI strombolian and/or vulcanian style eruptions took place [9]. The last eruptive cycle at Vesuvius lasted from 1631 to 1944 [9]. The AD 1944 eruption is the last eruption of Vesuvius Cone. Now, the volcano is in a repose period, which can be followed by a Plinian eruption. The behavior of Vesuvius volcano in the last 3800 years BP can be seen in **Figure 5** [9]. After the famous Avellino

*Somma-Vesuvius stratigraphic sketch with Somma activity and Vesuvius activity with style of eruption.*

*DOI: http://dx.doi.org/10.5772/intechopen.89989*

**Figure 2.** *Aerial photo of Somma-Vesuvius (Somma caldera e Vesuvius cone).*

## *The Somma-Vesuvius Activity with a Focus to the AD 79 Eruption: Hazard and Risk DOI: http://dx.doi.org/10.5772/intechopen.89989*

caldera. The Somma caldera is well exposed and looking from the North side (from Pollena town); the Vesuvius nested cone is hidden (**Figure 3**). Somma volcano should have been around 2000–2500 m high extrapolating from Somma Caldera, much higher than actual altitude of Vesuvius cone (Rolandi, unpublished data) [8]. The analysis of the eruptive history of Somma-Vesuvius (**Figure 4**) reveals the recurrence of highly explosive events followed by repose periods, during some of which low (2-3-4) VEI strombolian and/or vulcanian style eruptions took place [9]. The last eruptive cycle at Vesuvius lasted from 1631 to 1944 [9]. The AD 1944 eruption is the last eruption of Vesuvius Cone. Now, the volcano is in a repose period, which can be followed by a Plinian eruption. The behavior of Vesuvius volcano in the last 3800 years BP can be seen in **Figure 5** [9]. After the famous Avellino

#### **Figure 3.** *Somma caldera seen from North to West.*

*Forecasting Volcanic Eruptions*

issue with their family.

**40 ka BP**

light and ease the Neapolitan population that live around Somma-Vesuvius in case of future Plinian eruption. This simplified review on an open access international journal can also be available for students and general population and help high school students to understand the hazard of Somma-Vesuvius and to discuss this

The volcanic stratigraphy has been studied in detail in the last 40 ka BP [7]. Before this age, the volcano was looking like the Fuji volcano in Japan today (**Figure 1**). This analogy can be a best guess of the Somma volcano before 40 ka BP. The eruptive history of Somma volcano can be studied only on the Somma Caldera wall, which is poorly studied. Today, the volcano called Somma-Vesuvius volcano looks like the one shown in **Figure 2**. The aerial photo shows clearly the two morphologic characteristics: Somma caldera and Vesuvius cone nested into the

**2. Short notes on the stratigraphy of Somma-Vesuvius in the last** 

**82**

**Figure 2.**

**Figure 1.**

*Fujiyama volcano, Japan (taken from the Web).*

*Aerial photo of Somma-Vesuvius (Somma caldera e Vesuvius cone).*

**Figure 4.**

*Somma-Vesuvius stratigraphic sketch with Somma activity and Vesuvius activity with style of eruption.*

#### **Figure 5.**

*Activity of Somma-Vesuvius from Avellino eruption to the 1944 eruption: Plinian, interplinian and repose time [9]. The interplinian is defined as volcanic cyclic period less explosive after each Plinian eruption.*

prehistoric Plinian eruption, the Somma changed its eruption behavior, and the sequence of Plinian-interplinian-repose time took place until 1944. The protohistoric interplinian phase was followed by 700 years of repose time before the AD 79 eruption (**Figures 4** and **5**) [9]. According to this sequence, the next eruption at Vesuvius would be of the Plinian style. The Vesuvius matter would be to guess the size of the next Plinian eruption: Avellino-like, AD 79 eruption-like, Pollena-like, and 1631 eruption-like. This is still matter of study if the future eruption will be Subplinian, Plinian, or Ultraplinian.

## **3. Somma volcano before the AD 79 eruption**

Somma volcano, *Vesuvio* for Roman people, before the AD 79 eruption, raised no worry to people living in the volcanic area. The wall painting found in the archaeological excavation of Pompeii depicts the volcano as a one-peaked mountain (**Figure 6**). Bacco indicates the pleasant life of the time and the fertility of soils. No reference is made to the presence of phenomena (e.g., fumaroles) typical of an active volcanic area. Even in Latin literature (Virgilio, Seneca, Pliny the elder, Columella), the volcano is known only for fertility of its soils. Vitruvio is the only writer to put forward the hypothesis that in the past, although all his contemporaries had forgotten the fact, the volcano had been devastated by powerful eruptions (**Figure 6**). The Greeks wrote of the age, on the contrary, as Diodoro Siculo (80–20 BC) and the geographer Strabo (1st century BC–AD 19) describe morphological features of Vesuvio volcano: *…flat, without vegetation, similar to ash in appearance, with porous holes in the rocks which are black in colour as if they had been burnt… This is probably why the soils are so fertile … like Catania… covered by the eruptive ashes from Etna's fire…* (Strabo) (**Figure 7**)*.* Even seismic activity was not taken into account as a precursor of an eruption, but it was more simply linked to seismogenetic activity of the Apennine Chain. Seneca, in Quaestiones Naturales, does not quote Vesuvio when he describes the Pompeii earthquake on February 5 AD 62. The author, not aware of the seismogenesis of volcanic areas, does not recognize this earthquake as a possible precursor of a volcanic event (**Figure 8**). In [8, 10], it is shown how the evolution of the Somma caldera has been very complex with only the post activity of AD 472 called interplinian started with the growth of Vesuvius cone [9].

**85**

**Figure 8.**

**Figure 6.**

**Figure 7.**

*The Somma-Vesuvius Activity with a Focus to the AD 79 Eruption: Hazard and Risk*

*Drawing of Somma volcano during the AD 79 eruption (note a one peaked volcano conversely to the actual* 

*two-peaked volcano). Artist unknown found in one Pompei room.*

*Drawing of Somma volcano after the Codola eruption and probably Sarno eruption.*

*Roman marble sculpture witnessing the earthquake of the AD 62.*

*DOI: http://dx.doi.org/10.5772/intechopen.89989*

*The Somma-Vesuvius Activity with a Focus to the AD 79 Eruption: Hazard and Risk DOI: http://dx.doi.org/10.5772/intechopen.89989*

#### **Figure 6.**

*Forecasting Volcanic Eruptions*

**Figure 5.**

Subplinian, Plinian, or Ultraplinian.

**3. Somma volcano before the AD 79 eruption**

prehistoric Plinian eruption, the Somma changed its eruption behavior, and the sequence of Plinian-interplinian-repose time took place until 1944. The protohistoric interplinian phase was followed by 700 years of repose time before the AD 79 eruption (**Figures 4** and **5**) [9]. According to this sequence, the next eruption at Vesuvius would be of the Plinian style. The Vesuvius matter would be to guess the size of the next Plinian eruption: Avellino-like, AD 79 eruption-like, Pollena-like, and 1631 eruption-like. This is still matter of study if the future eruption will be

*[9]. The interplinian is defined as volcanic cyclic period less explosive after each Plinian eruption.*

*Activity of Somma-Vesuvius from Avellino eruption to the 1944 eruption: Plinian, interplinian and repose time* 

Somma volcano, *Vesuvio* for Roman people, before the AD 79 eruption, raised no worry to people living in the volcanic area. The wall painting found in the archaeological excavation of Pompeii depicts the volcano as a one-peaked mountain (**Figure 6**). Bacco indicates the pleasant life of the time and the fertility of soils. No reference is made to the presence of phenomena (e.g., fumaroles) typical of an active volcanic area. Even in Latin literature (Virgilio, Seneca, Pliny the elder, Columella), the volcano is known only for fertility of its soils. Vitruvio is the only writer to put forward the hypothesis that in the past, although all his contemporaries had forgotten the fact, the volcano had been devastated by powerful eruptions (**Figure 6**). The Greeks wrote of the age, on the contrary, as Diodoro Siculo (80–20 BC) and the geographer Strabo (1st century BC–AD 19) describe morphological features of Vesuvio volcano: *…flat, without vegetation, similar to ash in appearance, with porous holes in the rocks which are black in colour as if they had been burnt… This is probably why the soils are so fertile … like Catania… covered by the eruptive ashes from Etna's fire…* (Strabo) (**Figure 7**)*.* Even seismic activity was not taken into account as a precursor of an eruption, but it was more simply linked to seismogenetic activity of the Apennine Chain. Seneca, in Quaestiones Naturales, does not quote Vesuvio when he describes the Pompeii earthquake on February 5 AD 62. The author, not aware of the seismogenesis of volcanic areas, does not recognize this earthquake as a possible precursor of a volcanic event (**Figure 8**). In [8, 10], it is shown how the evolution of the Somma caldera has been very complex with only the post activity of AD 472 called interplinian started with the growth of

**84**

Vesuvius cone [9].

*Drawing of Somma volcano during the AD 79 eruption (note a one peaked volcano conversely to the actual two-peaked volcano). Artist unknown found in one Pompei room.*

#### **Figure 7.**

*Drawing of Somma volcano after the Codola eruption and probably Sarno eruption.*

**Figure 8.** *Roman marble sculpture witnessing the earthquake of the AD 62.*
