All earthquakes
4.4
moderate
EARTHQUAKE DETAILS

8 km West of Vittoria

69 months ago · 22 Dec, 21:27

A moderate earthquake, felt by people in the area. At this depth the shaking is felt, but rarely causes damage.

No. 12 of the year in ItalyStronger than 99% of Italian events in the past yearNo. 2 of the year in SiciliaThe strongest of the past 12 months within 50 km

Where

8 km West of VittoriaEarthquakes in the province of RagusaEarthquakes in Sicilia

How far away could it be felt?

An estimate of how far people may have felt this quake.

  • up to ~13 km · felt by many people, especially on upper floors
    ≈ 71,000 people live in this area
  • up to ~62 km · felt only by some, at rest
    ≈ 805,000 people live in this area

The coloured rings on the map below show these distances.

Statistical estimate from the Italian intensity attenuation model (INGV): actual perception depends on geology, buildings and depth. Very shallow events can be felt locally even below the threshold.

Earthquake map

5 events
Magnitude:lightweakmoderatestrong

The energy released

How much energy this quake unleashed, translated into everyday comparisons.

60tof TNT equivalent
251 lightning bolts
M3
×126 the energy of a magnitude 3 earthquake
M3this quakeM5

Each extra magnitude unit releases about 32 times more energy: an M5 is not "a bit stronger" than an M4 — it is a different league.

Energy estimated with the standard Gutenberg–Richter relation; an average lightning bolt ≈ 1 billion joules. Indicative values.

The race of the seismic waves

Two waves set off from the hypocentre: the faster P wave arrives first with a sharp jolt; the S wave carries the actual shaking.

P waves — the first sharp jolt (~6 km/s)S waves — the strongest shaking (~3.5 km/s)
t ≈ 14 s

Animation sped up ~3× compared to reality.

  • Vittoria
    8 km from the epicentre
    first tremor in ~5 s
    main shaking in ~9 s
  • Gela
    22 km from the epicentre
    first tremor in ~6 s
    main shaking in ~11 s
  • Ragusa
    23 km from the epicentre
    first tremor in ~6 s
    main shaking in ~11 s
  • Modica
    39 km from the epicentre
    first tremor in ~8 s
    main shaking in ~14 s

Theoretical times with average crustal speeds: real values vary with geology. The gap between P and S waves is what earthquake early-warning systems rely on.

How deep it was born

30 km
medium depth
3.3 times the height of Mount Everest

At this depth the shaking is felt, but rarely causes damage.

deeper than the area average (~21 km)

For the same magnitude, a shallow earthquake is felt much more than a deep one: the energy starts closer to the surface.

What kind of quake is this?

Mainshock

It is the strongest quake of its sequence: so far it has been followed by 4 aftershocks within 30 km. Aftershocks tend to fade in number and strength over time.

Activity in the area right now (30 km radius)
0
last 24 hours
0
last 7 days
3
last 30 days
0 before4 after
this quake
Strongest of the sequence2.0

How often does it happen here?

about every ~5.8 years

Within 50 km of this epicentre, a magnitude ≥ 4 earthquake has occurred on average this often: 2 events in the last 12 years of the INGV catalogue.

An average computed on the recent past: it tells how used this area is to shaking, not when the next quake will come — earthquakes cannot be predicted.

The great earthquakes in this area's history

Almost a thousand years of catalogues: the strongest documented events within ~50 km.

18185.6
Monti Iblei earthquake
1 March 1818 · 43 km from here
VII-VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
16245.6
Monti Iblei settentrionali earthquake
3 October 1624 · 48 km from here
IXDestructive: many buildings partly or fully collapse.
19095.3
Caltagirone earthquake
2 January 1909 · 35 km from here
VII-VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
19495.1
Sicilia sud-orientale earthquake
8 October 1949 · 24 km from here
VIIVery strong: hard to stand; chimneys and roof tiles fall, serious damage to weaker buildings.

Source: Parametric Catalogue of Italian Earthquakes CPTI15 (INGV, CC BY 4.0).

The closest seismic structure

Gela-Catania

The epicentre lies about 22 km from Gela-Catania, one of the seismic structures mapped by INGV geologists.

estimated maximum magnitude 7.1between 3 and 10 km deep

Faults are mapped to build better and understand the territory: knowing them says nothing about when an earthquake will occur, which remains unpredictable. Source: DISS 3.3 (INGV, CC BY 4.0).

Other quakes in the area

2.0
9 km South-West of Acate
4 km North-West · 26 km
69 months ago
22 Dec, 21:37
1.6
9 km South-West of Acate
4 km North-West · 25 km
69 months ago
23 Dec, 00:37
1.4
10 km South-West of Acate
6 km North-West · 26 km
69 months ago
23 Dec, 01:39
1.6
69 months ago
25 Dec, 13:45

Data: INGV — National Institute of Geophysics and Volcanology (CC-BY 4.0)

Estimates computed by Meteare on INGV data (Gutenberg–Richter relation; Italian macroseismic intensity attenuation model).

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