All earthquakes
1.8
very light
EARTHQUAKE DETAILS

1 km West of Villarosa

138 months ago · 22 Apr, 11:45

A very light earthquake, probably not felt by people. Being deep, it is felt less at the surface.

Stronger than 82% of Italian events in the past year

Where

1 km West of VillarosaEarthquakes in the province of EnnaEarthquakes in Sicilia

How far away could it be felt?

A quake this small is usually not felt by people: only seismographs record it.

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

3 events
Magnitude:lightweakmoderatestrong

The energy released

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

7.6kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×63 its energy
M1this quakeM3

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 ≈ 29 s

Animation sped up ~5× compared to reality.

  • Caltanissetta
    18 km from the epicentre
    first tremor in ~12 s
    main shaking in ~20 s
  • Gela
    55 km from the epicentre
    first tremor in ~14 s
    main shaking in ~25 s
  • Agrigento
    59 km from the epicentre
    first tremor in ~15 s
    main shaking in ~25 s
  • Vittoria
    77 km from the epicentre
    first tremor in ~17 s
    main shaking in ~29 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

66 km
deep
7.5 times the height of Mount Everest

Being deep, it is felt less at the surface.

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?

Foreshock

In hindsight it was a foreshock: 138 months ago the same area had a stronger quake (M2.1). This can only be said after the fact — it was not predictable beforehand.

2.1
The mainshock
3 km South-East of Gangi
138 months ago · 25 Apr, 14:22
Activity in the area right now (30 km radius)
0
last 24 hours
0
last 7 days
1
last 30 days
0 before2 after
this quake
Strongest of the sequence2.1

How often does it happen here?

about every ~9 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 463 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.

18195.4
Monti Madonie earthquake
24 February 1819 · 40 km from here
VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
18185.3
Monti Madonie earthquake
8 September 1818 · 26 km from here
VII-VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
19675.3
Monti Nebrodi earthquake
31 October 1967 · 38 km from here
VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
17185.3
Sicilia orientale earthquake
20 February 1718 · 41 km from here
VI-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 37 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

2.1
3 km South-East of Gangi
19 km North-East · 70 km
138 months ago
25 Apr, 14:22
1.4
8 km North-West of Raddusa
30 km East · 55 km
138 months ago
1 May, 23:12

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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