All earthquakes
1.2
very light
EARTHQUAKE DETAILS

5 km South-East of Geraci Siculo

67 months ago · 18 Feb, 10:43

A very light earthquake, probably not felt by people. At only a few km deep the shaking is felt more sharply at the surface.

Stronger than 47% of Italian events in the past year

Where

5 km South-East of Geraci SiculoEarthquakes in the province of PalermoEarthquakes 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

35 events
Magnitude:lightweakmoderatestrong

The energy released

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

1.0kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×501 its energy
M0this quakeM2

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 ≈ 23 s

Animation sped up ~4× compared to reality.

  • Caltanissetta
    43 km from the epicentre
    first tremor in ~7 s
    main shaking in ~13 s
  • Bagheria
    69 km from the epicentre
    first tremor in ~12 s
    main shaking in ~20 s
  • Agrigento
    79 km from the epicentre
    first tremor in ~13 s
    main shaking in ~23 s
  • Gela
    80 km from the epicentre
    first tremor in ~14 s
    main shaking in ~23 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

10 km
shallow
1.1 times the height of Mount Everest

At only a few km deep the shaking is felt more sharply at the surface.

shallower than the area average (~18 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?

Aftershock

It is an aftershock: it follows a stronger quake (M2.8, 67 months ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

2.8
The mainshock
3 km East of San Mauro Castelverde
67 months ago · 16 Feb, 11:10
Activity in the area right now (30 km radius)
0
last 24 hours
2
last 7 days
17
last 30 days
14 before20 after
this quake
Strongest of the sequence2.8

How often does it happen here?

about every ~6 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 717 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.

18235.8
Sicilia settentrionale earthquake
5 March 1823 · 42 km from here
VIII-IXDestructive: many buildings partly or fully collapse.
18195.4
Monti Madonie earthquake
24 February 1819 · 20 km from here
VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
18185.3
Monti Madonie earthquake
8 September 1818 · 12 km from here
VII-VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
19675.3
Monti Nebrodi earthquake
31 October 1967 · 18 km from here
VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.

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

The closest seismic structure

Gela-Catania

The epicentre lies about 55 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

0.8
8 km South-East of Isnello
13 km West · 6 km
67 months ago
19 Feb, 05:42
2.8
67 months ago
16 Feb, 11:10
1.4
3 km North-West of Castel di Lucio
9 km North-East · 25 km
67 months ago
21 Feb, 06:23
1.1
6 km South-East of Geraci Siculo
1 km South-East · 10 km
67 months ago
22 Feb, 22:10
1.3
67 months ago
24 Feb, 23:34
2.6
5 km West of Capizzi
19 km East · 37 km
68 months ago
11 Feb, 17:47
1.9
67 months ago
25 Feb, 03:53
1.6
6 km South-East of Geraci Siculo
1 km South-East · 8 km
67 months ago
25 Feb, 03:58
1.3
5 km East of Geraci Siculo
1 km North-East · 10 km
67 months ago
25 Feb, 04:26
1.6
6 km North of Gangi
2 km South · 9 km
67 months ago
25 Feb, 07:04

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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