Comprehensive Risk Assessment for Natural Hazards - Planat

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Chapter 4 — Volcanic hazards
Figure 4.2 — Hawaiian type (Type example, Hawaii, USA)
Figure 4.3 — Pelean type (Type example Mt Pelé,
Martinique, French West Indies)
Figure 4.4 — Plinian type (Defined at Vesuvius, Italy)
Figure 4.5 — Vulcanian type (Defined at Vulcano, Italy)
SO 2 Sulfur dioxide
CO 2 Carbon dioxide
HF Hydrofluoric acid, etc.
Figure 4.6 — Strombolian type (Defined at Stromboli, Italy)
Figure 4.7 — Sketch of gas emission
Figure 4.9 — Sketch of a landslide
Figure 4.8 — Sketch of a lahar
Fig. 4.10 — Sketch of a tsunami
4.2 DESCRIPTION AND CHARACTERISTICS OF
THE MAIN VOLCANIC HAZARDS
An active volcano can produce different hazards as
defined by the IAVCEI (1990). These can be subdivided
into:
• Primary or direct hazards due to the direct impact of
the eruption products.
• Secondary or indirect hazards due to secondary consequences
of an eruption.
4.2.1 Direct hazards
One can distinguish four principal types of direct volcanic
hazards (Holmes, 1965). These are: lava flows; pyroclastic
flows; ash fulls and block falls; and gases:
(a) Lava flows (Figure 4.2);
(b) Pyroclastic flows such as pumice flow, nuée ardente,
base surge, … (Figure 4.3);
(c) Ash falls and block falls (Figures 4.4, 4.5 and 4.6);
(d) Gases (Figure 4.7).