Publication Date:
2017-04-04
Description:
Public works in progress in the Campanian plain north of Somma-
^
Vesuvius recently encountered the remains
15 of a prehistoric settlement close to the town of Afragola. Rescue excavations brought to light a Bronze Age
16 village partially destroyed and buried by pyroclastic density currents (PDCs) of the Vesuvian Pomici di
17 Avellino eruption (3.
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8 14C ka BP) and subsequently sealed by alluvial deposits. Volcanological and rock-
18
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magnetic investigations supplemented the excavations.
19 Careful comparison between volcanological and archaeological stratigraphies led to an understanding of the
20 timing of the damage the buildings suffered when they were struck by a series of PDCs. The first engulfed the
21 village, located some 15 km to the north of the inferred vent, and penetrated into the dwellings without
22 causing major damage. The buildings were able to withstand the weak dynamic pressure of the currents and
23 deviate their path, as shown by the magnetic fabric analyses. Some later collapsed under the load of the
24 deposits piled up by successive currents. Stepwise demagnetization of the thermal remanent magnetization
25 (TRM) carried by potsherds embedded in the deposits yields deposition temperatures in the order of 260–
26
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320 °C, fully consistent with those derived from pottery and lithic fragments from other distal and proximal
27 sites. The fairly uniform temperature of the deposits is here ascribed to the lack of pervasive air entrainment
28 into the currents. This, in turn, resulted from the lack of major topographical obstacles along the flat plain.
29 The coupling of structural damage and sedimentological analyses indicates that the currents were not
30 destructive in the Afragola area, but TRM data indicate they were still hot enough to cause death or severe
31 injury to humans and animals. The successful escape of the entire population is apparent from the lack of
32 human remains and from thousands of human footprints on the surface of the deposits left by the first PDCs.
33 People were thus able to walk barefoot across the already emplaced deposits and escape the subsequent
34 PDCs. The rapid cooling of the deposits was probably due to both their thinness and heat dissipation due to
35 condensation of water vapour released in the mixture by magma–water interaction
Description:
In press
Description:
3.5. Geologia e storia dei sistemi vulcanici
Description:
3.6. Fisica del vulcanismo
Description:
JCR Journal
Description:
reserved
Keywords:
pyroclastic density current
;
Bronze Age
;
magnetic fabric
;
deposition temperature
;
04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous
;
04. Solid Earth::04.04. Geology::04.04.10. Stratigraphy
;
04. Solid Earth::04.05. Geomagnetism::04.05.99. General or miscellaneous
;
04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
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