Publication Date:
2021-06-15
Description:
Public works in progress in the Campanian plain north of Somma-Vesuvius recently encountered the remains
of a prehistoric settlement close to the town of Afragola. Rescue excavations brought to light a Bronze Age
village partially destroyed and buried by pyroclastic density currents (PDCs) of the Vesuvian Pomici di
Avellino eruption (3.8 14C ka BP) and subsequently sealed by alluvial deposits. Volcanological and rockmagnetic
investigations supplemented the excavations.
Careful comparison between volcanological and archaeological stratigraphies led to an understanding of the
timing of the damage the buildings suffered when they were struck by a series of PDCs. The first engulfed the
village, located some 14 km to the north of the inferred vent, and penetrated into the dwellings without
causing major damage. The buildings were able to withstand the weak dynamic pressure of the currents and
deviate their path, as shown by the magnetic fabric analyses. Some later collapsed under the load of the
deposits piled up by successive currents. Stepwise demagnetization of the thermal remanent magnetization
(TRM) carried by potsherds embedded in the deposits yields deposition temperatures in the order of 260–
320 °C, fully consistent with those derived from pottery and lithic fragments from other distal and proximal
sites. The fairly uniform temperature of the deposits is here ascribed to the lack of pervasive air entrainment
into the currents. This, in turn, resulted from the lack of major topographical obstacles along the flat plain.
The coupling of structural damage and sedimentological analyses indicates that the currents were not
destructive in the Afragola area, but TRM data indicate they were still hot enough to cause death or severe
injury to humans and animals. The successful escape of the entire population is apparent from the lack of
human remains and from thousands of human footprints on the surface of the deposits left by the first PDCs.
People were thus able to walk barefoot across the already emplaced deposits and escape the subsequent
PDCs. The rapid cooling of the deposits was probably due to both their thinness and heat dissipation due to
condensation of water vapour released in the mixture by magma–water interaction.
Description:
Published
Description:
408–421
Description:
2.3. TTC - Laboratori di chimica e fisica delle rocce
Description:
3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
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::04.04.10. Stratigraphy
;
04. Solid Earth::04.05. Geomagnetism::04.05.07. Rock magnetism
;
04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
