Table 1.

Summary of the Environmental Seismic Intensity scale (ESI 2007) for intensities VII–X (Michetti et al. 2007)

EEE type/degreeVIIVIIIIXX
Damaging – Appreciable effects on the environmentHeavily damaging – Extensive effects on the environmentDestructive – Environmental effects are a widespread source of considerable hazard and become important for intensity assessmentVery destructive – Effects in the environment become a leading source of hazards and are critical for intensity assessment
Surface faultingPrimary effects observed very rarely.Primary effects observed rarely. Ground ruptures (surface faulting) may develop, up to several hundred meters long, with offsets not exceeding a few cm, particularly for very shallow focus earthquakes. Tectonic subsidence or uplift with maximum values on the order of a few centimetres may occur.Primary effects observed commonly. Ground ruptures (surface faulting) develop, up to a few km long, with offsets generally in the order of several cm. Tectonic subsidence or uplift of the ground surface with maximum values in the order of a few decimetres may occur.Primary ruptures become leading. Surface faulting can extend for few tens of km, with offsets from tens of cm up to a few metres. Gravity grabens and elongated depressions develop; Tectonic subsidence or uplift with maximum values in the order of few meters may occur.
Slope movementsScattered landslides occur in prone areas; (steep slopes of loose/saturated soils; rock falls on steep gorges, coastal cliffs) their size is sometimes significant (103–105 m3. The affected area is in the order of 10 km2.Small to moderate (103–105 m3) landslides widespread in prone areas; their size is sometimes large (105–106 m3). Ruptures, slides and falls affect riverbanks and artificial embankments in loose sediment or weathered/ fractured rock. The affected area is in the order of 100 km2.Landsliding widespread in prone areas, also on gentle slopes; where equilibrium is unstable (steep slopes of loose/saturated soils; rock falls on steep gorges, coastal cliffs) their size is frequently large (105 m3), sometimes very large (106 m3). Riverbanks, artificial embankments and excavations (e.g. road cuts, quarries) frequently collapse. The affected area is in the order of 1000 km2.Large landslides and rock-falls (>105–106 m3) are frequent, practically regardless of equilibrium state of the slopes, causing temporary or permanent barrier lakes. River banks, artificial embankments, and sides of excavations typically collapse. Levees and earth dams may even incur serious damage. The affected area is in the order of 5000 km2.
Ground cracksFractures up to 5–10 cm wide and up to hundred metres long commonly in loose alluvial deposits and/or saturated soils; Centimetre-wide cracks common in paved (asphalt or stone) roads.Fractures up to 50 cm wide and up to hundred metres long are commonly observed in loose alluvial deposits and/or saturated soils; in rare cases fractures up to 1 cm can be observed in competent dry rocks. Decimetric cracks common in paved roads, as well as small pressure undulations.Fractures up to 100 cm wide and up to hundred metres long are commonly observed in loose alluvial deposits and/or saturated soils; in competent rocks they can reach up to 10 cm. Significant cracks common in paved (asphalt or stone) roads, as well as small pressure undulations.Open ground cracks up to more than 1 m wide and up to hundred metres long are frequent, mainly in loose alluvial deposits and/or saturated soils; in competent rocks opening reaches several decimetres. Wide cracks develop in paved (asphalt or stone) roads, as well as pressure undulations.
Ground settlements–collapse/tsunami/other effectsRare cases of liquefaction, with sand boils up to 50 cm in diameter, in areas most prone to this phenomenon (highly susceptible, recent, alluvial and coastal deposits, shallow water table).Liquefaction may be frequent in the epicentral area; sand boils up to c. 1 m in diameter; localized lateral spreading and settlements (subsidence up to c. 30 cm), with fissuring parallel to waterfront areas (river banks, lakes, canals, seashores). Waves up to 1–2 m high develop in nearshore areas and may damage of wash away objects of variable size.Liquefaction and water upsurge are frequent; sand boils up to 3 m in diameter; frequent lateral spreading and settlements (subsidence of more than c. 30 cm), with fissuring parallel to waterfront areas (river banks, lakes, canals, seashores). Metre-high waves develop in still and running waters. Tsunamis may reach the coastal areas with runups of up to several metres flooding wide areas. Small boulders and tree trunks may be thrown in the air.Liquefaction, with water upsurge and soil compaction, may change the aspect of wide zones; sand volcanoes even more than 6 m in diameter; vertical subsidence even >1 m; large and long fissures due to lateral spreading are common. Metre-high waves develop in still and running waters. Tsunamis may reach the shores with runups exceeding 5 m flooding flat areas for thousands of metres in land. Boulders (diameter in excess of 2–3 m) can be thrown in the air.
  • This table includes only the definitions of intensities VII–X that are used in the paper.