Structural height, amplification and damages during the superficial earthquakes at Casamicciola, Ischia Island (2017), and Santa Venerina, Catania (2018), Italy

Figures & data

Figure 1. Simplified scheme of the numerical steps.

Table 1. Numerical damage scale.

Damage	Value	Description
Absent	0	No damage
Low	1	Small number of light superficial fissures in the plaster a few millimeters wide. Horizontal displacements without expulsion of material
	2	Diffuse light superficial fissures. Limited separations. Falls of small pieces of plaster or stucco not bound to the wall and degraded
Medium	3	Superficial fissures and some deep fissures 1 cm wide. Damage to the roof. Possible falls of non- structural objects
	4	Numerous superficial fissures and deep fissures 1 cm wide or wider near the openings (crushing mechanism). Slight separations between floor assemblies and/or staircases and orthogonal walls (of 1 mm). Lesions to the vaults of several millimeters and/or with symptoms of crushing
	5	Numerous superficial fissures and deep fissures 1 cm wide distributed on parts of the building. Detachments in the secondary framework of the floor assemblies and displacements of up to 1 cm of the main beam supports. Significant damage to the roof with falls of tiles. Visible non-verticalities
High	6	Structural damage compromising the safety of the residents. Parts of the structure damaged but not in imminent danger
	7	Structural damage causing instability. Parts of the structure damaged and separated from the body of the building. Significant separations between floor assemblies and/or staircases and walls and between orthogonal walls of ca. 1 cm
	8	Structural damage compromising stability. Parts of the structure detached by building collapse and partial collapses. Non-verticality with lesions passing through the masonry
Very high	9	Diffuse structural collapses, but most of the structure still recognizable with danger risk for the residents (instability-dangerousness). Collapse of 50% of the building
	10	Complete or almost complete collapse

Figure 2. (a) Low damage. (b) Medium damage. (c) High damage. (d) Very high damage.

Figure 3. Epicenter of the earthquake of 21 August 2017. Localities and seismic station.

Figure 4. Epicenter of the earthquake of 26 December 2018. Localities and seismic station.

Figure 5. DAF(H) for ζ = 8% (masonry buildings). Casamicciola. Earthquake of 21 August 2017 18:57:51 UTC M_w 4.0. IOCA station.

Figure 6. DAF(H) for ζ = 5% (reinforced concrete buildings). Santa Venerina. Earthquake of 26 December 2018 02:19:14 UTC M_w 4.8. SVN station.

Table 2. Casamicciola. Earthquake of 21 August 2017 18:57:51 UTC M_w 4.0. IOCA station. Maximum DAF_m for ζ = 5% (reinforced concrete buildings) and ζ = 8% (masonry buildings).

Seismic station	de (km)	PGA (g)	td (sec)	To (sec) ζ = 5%	DAF max ζ = 5%	To (sec) ζ = 8%	DAF max ζ = 8%
IOCA	0.65	0.214	3	0.174	3.0	0.192	2.4

Table 3. Santa Venerina. Earthquake of 26 December 2018 02:19:14 UTC M_w 4.8. SVN station. Maximum DAF_m for ζ = 5% (reinforced concrete buildings) and ζ = 8% (masonry buildings).

Seismic station	de (Km)	PGA (g)	td (sec)	To (sec) ζ = 5%	DAFm max ζ = 5%	To (sec) ζ = 8%	DAFm max ζ = 8%
SVN	6.96	0.519	3	0.204	2.0	0.210	1.7

Table 4. Casamicciola. Earthquake of 21 August 2017 18.57.51 UTC M_w 4.0. $\widehat{\mathrm{ }\mathrm{DAF}}m,$ critical height H_c, critical story P_c. α = 0.05; β = 0.75; ζ = 8% (masonry buildings).

Seismic station	$\widehat{\mathrm{ }\mathrm{DAF}}m$	Class	Hc (m)	Pc
IOCA	2.4	II	5.5-5.75-6.0	2

Table 5. Santa Venerina. Earthquake of 26 December 2018 02:19:14 UTC M_w 4.8. $\widehat{\mathrm{ }\mathrm{DAF}}m,$ critical height H_c, critical story P_c. α = 0.075; β = 0.75; ζ = 5% (reinforced concrete buildings).

Seismic station	$\widehat{\mathrm{ }\mathrm{DAF}}m$	Class	Hc (m)	Pc
SVN	1.8	II	5.5-5.75-6.0	2

Table 6. Casamicciola. Earthquake of 21 August 2017 18.57.51 UTC M_w 4.0. Locality, percentage of buildings with damage greater than 5, mean damage D_m and mean story P_m.

Locality	d epicenter (Km)	Residential buildings Damage > 5 (%)	Dm	Pm
Casamicciola	0.5	46	7.4	1.9
Bagni	0.7	30	7.0	2.0
Fango	1.5	41	5.8	2.0
Lacco Ameno	1.9	76	7.2	2.0

Table 7. Santa Venerina. Earthquake of 26 December 2018 02:19:14 UTC M_w 4.8. Locality, percentage of buildings with damage greater than 5, mean damage D_m and mean story P_m.

Locality	d epicenter (Km)	Residential buildings Damage > 5 (%)	Dm	Pm
Fleri	4.8	32	6.2	2.1
Pennisi	5.4	33	6.0	2.0

Figure 7. Casamicciola. Earthquake of 21 August 2017 18.57.51 UTC M_w 4.0. Masonry buildings: locality, mean damage D_m > 5, P_c and P_m.

Figure 8. Santa Venerina. Earthquake of 26 December 2018 02:19:14 UTC M_w 4.8. Reinforced concrete buildings: locality, mean damage D_m > 5, P_c and P_m.

Data availability statement

The data processed by the author in this paper are available upon request from him. The data from the seismic stations of Santa Venerina and IOCA can be requested from the Italian Department of Civil Protection and the National Institute of Geophysics and Volcanology – Vesuvius Observatory.