Interaction of pyroclastic density currents with human settlements: Evidence from ancient Pompeii

Gurioli, Lucia; Pareschi, M. T.; Zanella, Elena; Lanza, Roberto; Deluca, Enrico; Bisson, Marina

doi:10.1130/g21294.1

Cited by 64 publications

(59 citation statements)

References 31 publications

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“…phreatomagmatic eruptions), such as the case of the PA ignimbrite. While the temperature range for the PA is similar to paleomagnetic estimates for other non-phreatomagmatic pyroclastic flow units (Bardot et al 1996;Cioni et al 2004;Gurioli et al 2005), an important observation is that the emplacement temperatures for the PA do not vary significantly with distance and facies and are similarly low at very proximal locations (i.e. within the crater).…”

Section: Veneer Facies Resultsmentioning

confidence: 64%

Paleomagnetic evidence for low-temperature emplacement of the phreatomagmatic Peperino Albano ignimbrite (Colli Albani volcano, Central Italy)

et al. 2007

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The Peperino Albano (approximately 19-36 ka old) is a phreatomagmatic pyroclastic flow deposit, cropping out along the slopes of the associated Albano maar (Colli Albani volcano, Italy). The deposit exhibits lateral and vertical transitions from valley pond to veneer facies, as well as intracrater facies. We present the results of a paleomagnetic study of thermal remanent magnetization (TRM) of the lithic clasts of the Peperino Albano ignimbrite that provide quantitative estimates of the range of emplacement temperatures across the different facies of the ignimbrite. Emplacement temperatures estimated for the Peperino Albano ignimbrite range between 240°and 350°C, with the temperatures defined in the intracrater facies being generally lower than in the valley pond and veneer facies. This is possibly due to the large size of the sampled clasts in the intracrater facies which, when coupled with low temperature at the vent, were not completely heated throughout their volume during emplacement. The emplacement temperatures derived from the paleomagnetic results are in good agreement with the presence of un-burnt plants at the base of the ignimbrite, indicating that the temperature of the pyroclastic flow was lower than the temperature of ignition of wood. Paleomagnetic results from the Peperino Albano confirm the reliability of the paleomagnetic approach in defining the thermal history of pyroclastic flow deposits.

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Section: Veneer Facies Resultsmentioning

confidence: 64%

Paleomagnetic evidence for low-temperature emplacement of the phreatomagmatic Peperino Albano ignimbrite (Colli Albani volcano, Central Italy)

et al. 2007

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“…Lajoie et al 1998;Dellino et al 2004;). The application of rock-magnetic techniques to PDC deposits has recently allowed reliable information about their temperature at time of deposition (T dep - Cioni et al 2004;Gurioli et al 2005;Zanella et al 2007) to be estimated, this being a key parameter in understanding PDC dynamics and related hazard. Blong (1984) lists the thermal and mechanical factors that make PDCs an extreme hazard to humans, whereas Baxter et al (1998) consider a PDC minimum temperature of 200°C and ash concentration of 0.1 kg/m 3 to be threshold values above which human survival is likely impossible.…”

Section: Introductionmentioning

confidence: 99%

Deposition temperature of the AD 472 Pollena pyroclastic density current deposits, Somma-Vesuvius, Italy

et al. 2008

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The deposition temperature of the pyroclastic density current (PDC) deposits emplaced during the AD 472 Pollena eruption (Somma-Vesuvius, Italy) has been investigated using the thermal analysis of the magnetic remanence carried by lithic clasts embedded within the deposits. A total of 310 lithic clasts were collected from all the PDC units in the Pollena stratigraphic succession, at different distances from the inferred vent and at different stratigraphic levels. The temperature reached by each individual clast during residence in the PDC was estimated through stepwise thermal demagnetization, with the values from all clasts collected at each site being used to infer the deposition temperature (T dep ). Although the sedimentological features of these PDC deposits show some variation, the deposition temperature typically falls in the range 300 to 320°C, with a maximum range of 260 to 360°C. The fairly uniform temperature observed in both the dune bedded and massive deposits points to homogeneity in attainment of T dep for the different deposits and suggests similarity in the depositional regime of the different PDCs and/or in heat transfer to lithic fragments. Similarity in depositional regime was also favoured by the limited control exerted by topography on the distribution of these PDCs, with the northern wall of the Somma caldera that did not act as a morphological barrier. As a result the currents were capable of moving away from the vent, without topographic disturbances and, thus, significant variations in the cooling regime. Because the Pollena eruption is considered similar to the maximum expected event at Somma-Vesuvius, the characteristics of its deposits best simulate the likely maximum hazard for the Vesuvius region. In this regard, Pollena produced hot, dilute PDCs which were able to travel up to 12 km from the vent maintaining high temperatures across this distance.

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“…The inferred flow directions may be discordant in particular sites, as a consequence of local and topographical effects (Baer et al 1997). In some cases, the inferred flow directions may not be orientated parallel to the main palaeovalley axes but orientated at variable angles, or, in other cases, they may show evidence of backflow towards the vent (Fisher et al 1993;Ort et al 1999;Gurioli et al 2005Gurioli et al , 2007. All of these effects may be related to flow disturbance or blockage during transport and can be studied using a systematic AMS sampling of different facies in the pyroclastic deposits (see Ort et al 2014;Willcock et al 2014).…”

Section: Anisotropy Of Magnetic Susceptibility (Ams) As Magmatic Flowmentioning

confidence: 99%

The use of palaeomagnetism and rock magnetism to understand volcanic processes: introduction

Ort

Porreca

Geissman

2015

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This Special Publication provides a snapshot of our understanding of volcanic processes through the use of palaeomagnetic and rock magnetic techniques. Here, we provide a context for the book, placing individual chapters within the milieu of previous work, including some magnetic techniques that were not used in the particular studies described herein. Thermoremanent magnetization is a powerful tool to understand processes related to heating and cooling of rocks, including estimating the temperature of emplacement of pyroclastic deposits, which may allow us to better understand the rates of cooling during eruption and transport. Anisotropy of magnetic susceptibility and anisotropy of remanence are used primarily to investigate rock fabrics, and allow the interpretation of flow dynamics in dykes, lava flows and pyroclastic deposits, as well as the location of the eruptive vents. Rock magnetic characteristics can help in the correlation of volcanic deposits but also provide means to date volcanic deposits and to better understand the processes of cooling of the deposits, as the magnetic minerals can change with temperature. In addition, volcanic rocks may be key recorders of past magnetic fields, allowing a better understanding of changes in field intensity and, perhaps, providing clues of how the magnetic field is formed.

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Interaction of pyroclastic density currents with human settlements: Evidence from ancient Pompeii

Cited by 64 publications

References 31 publications

Paleomagnetic evidence for low-temperature emplacement of the phreatomagmatic Peperino Albano ignimbrite (Colli Albani volcano, Central Italy)

Paleomagnetic evidence for low-temperature emplacement of the phreatomagmatic Peperino Albano ignimbrite (Colli Albani volcano, Central Italy)

Deposition temperature of the AD 472 Pollena pyroclastic density current deposits, Somma-Vesuvius, Italy

The use of palaeomagnetism and rock magnetism to understand volcanic processes: introduction

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