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Table 8 Selected hazardous tephra-fallout accumulation thresholds (kg/m2) relevant for emergency and risk management on Vulcano in relation to buildings (Spence et al. 2005; Jenkins et al. 2014, 2015; Hayes et al. 2019), power systems/telecommunication (Jenkins et al. 2014, 2015) and roads/vehicles (Blake et al., 2017a,b; Jenkins et al. 2014; Wilson et al. 2017) and corresponding hazard score (1 to 7) used in Figs. 5 and 6. Tephra load (kg/m2) is converted in thickness assuming a deposit density of 1000 kg/m3. ND indicates no data available for this system. *Transport system mainly refers to Roads and vehicles, as no information is available for heliport and harbours; nonetheless, we can consider that disruption to airport occurs for thickness above 0.01 cm (Blake et al. 2017a)

From: Integrating hazard, exposure, vulnerability and resilience for risk and emergency management in a volcanic context: the ADVISE model

Buildings

ND

No structural damage to buildings; possible infiltration and internal contamination and corrosion of metallic components; roofing materials may be abraded or damaged by human actions during ash removal

In rare instances, non-engineered and long span roofs may be vulnerable to damage, particularly when ash falls wet or is subsequently wetted; non-structural elements such as gutters and overhangs may suffer damage; some infiltration of dry ash into interiors

Structural damage; partial to complete collapse of weak (timber, corrugated metal) roofs

Structural damage; partial to complete collapse of concrete roofs

Power system / telecommunication

ND

Temporary disruption of power system particularly with wet ash (e.g. flashovers); possible communication signal attenuation (e.g. radio); uninsulated lines may flashover.

Damage to telecommunication components and power cables through flashover; abrasion and or corrosion; failure of power generating plant (depending on system type and design); abrasion, clogging and flash-over causing disruption and/or damage to some electrical and mechanical equipment at substations

Damage to communication dishes and microwave towers due to excess of ash loading; structural damage to electrical distribution lines and support structures

Damage to communication dishes and microwave towers due to excess ash loading; permanent disruption and structural damage of power system

*Transport system

Minor skid resistance reduction possible and covering of markings

Skid resistance reduction likely and covering of markings; poor visibility; windscreen abrasion

Minor skid resistance reduction possible and covering of markings, poor visibility, windscreen abrasion

Minor skid resistance reduction possible and covering of markings; poor visibility; clogging of roadside drains and ditches; increased wear of engine and brakes and windscreen abrasion

Impassable for some vehicles and covering of markings; poor visibility. Dry, windy conditions exacerbate remobilisation and drifting.

Hazard score

1

2

3

4

5

6

7

Tephra load (kg/m2) / thickness (cm)

0.1–1 (0.01–0.1)

1–5 (0.1–0.5)

5–10 (0.5–1)

10–100 (1–10)

100–300 (10–30)

300–500 (30–50)

> 500 (> 50)