Publication Date:
2017-04-04
Description:
The paper explores the potential of tsunami generation
by pyroclastic flows travelling down the flank of the
volcano Vesuvius that is found south of Naples in Italy. The
eruption history of Vesuvius shows that it is characterised by
large explosive eruptions of plinian or subplinian type during
which large volume of pyroclastic flows can be produced.
The most remarkable examples of such eruptions occurred in
79 AD and in 1631 and were catastrophic. Presently Vesuvius
is in a repose time that, according to volcanologists,
could be interrupted by a large eruption, and consequently
proper plans of preparedness and emergency management
have been devised by civil authorities based on a scenario
envisaging a large eruption. Recently, numerical models of
magma ascent and of eruptive column formation and collapse
have been published for the Vesuvius volcano, and propagation
of pyroclastic flows down the slope of the volcanic
edifice up to the close shoreline have been computed. These
flows can reach the sea in the Gulf of Naples: the denser slow
part will enter the waters, while the lighter and faster part of
the flow can travel on the water surface exerting a pressure on
it. This paper studies the tsunami produced by the pressure
pulse associated with the transit of the low-density phase of
the pyroclastic flow on the sea surface by means of numerical
simulations. The study is divided into two parts. First
the hydrodynamic characteristics of the Gulf of Naples as
regards the propagation of long waves are analysed by studying
the waves radiating from a source that is a static initial
depression of the sea level localised within the gulf. Then
the tsunami produced by a pressure pulse moving from the
Vesuvius toward the open sea is simulated: the forcing pulse
features are derived from the recent studies on Vesuvian pyroclastic
flows in the literature. The tsunami resulting from
the computations is a perturbation involving the whole Gulf
of Naples, but it is negligible outside, and persists within the
gulf long after the transit of the excitation pulse. The size of
the tsunami is modest. The largest calculated oscillations are
found along the innermost coasts of the gulf at Naples and at Castellammare. The main conclusion of the study is that the
light component of the pyroclastic flows produced by future
large eruptions of Vesuvius are not expected to set up catastrophic
tsunamis.
Description:
Published
Description:
311-320
Description:
3.1. Fisica dei terremoti
Description:
3.3. Geodinamica e struttura dell'interno della Terra
Description:
4.3. TTC - Scenari di pericolosità vulcanica
Description:
JCR Journal
Description:
reserved
Keywords:
tsunami
;
volcanic activity
;
pyroclastic flow
;
numerical modeling
;
03. Hydrosphere::03.01. General::03.01.01. Analytical and numerical modeling
;
04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
;
04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
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