All earthquakes
1.6
very light
EARTHQUAKE DETAILS

M1.6 earthquake · 4 km West of Castel di Lucio (ME)

5 years ago · 15 Sept 2021, 14:06

A very light earthquake, probably not felt by people. At this depth the shaking is felt, but rarely causes damage.

Stronger than 74% of Italian events in the past year

Where

4 km West of Castel di LucioEarthquakes in the province of MessinaEarthquakes 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

13 events
Magnitude:lightweakmoderatestrong

The energy released

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

3.8kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×126 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 ≈ 24 s

Animation sped up ~5× compared to reality.

  • Caltanissetta
    49 km from the epicentre
    first tremor in ~8 s
    main shaking in ~14 s
  • Bagheria
    70 km from the epicentre
    first tremor in ~12 s
    main shaking in ~20 s
  • Catania
    82 km from the epicentre
    first tremor in ~14 s
    main shaking in ~24 s
  • Acireale
    85 km from the epicentre
    first tremor in ~14 s
    main shaking in ~24 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

11 km
medium depth
1.2 times the height of Mount Everest

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

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?

Foreshock

In hindsight it was a foreshock: 5 years ago the same area had a stronger quake (M2.3). This can only be said after the fact — it was not predictable beforehand.

2.3
The mainshock
2 km South-East of Geraci Siculo
5 years ago · 28 Sept 2021, 23:40
Activity in the area right now (30 km radius)
0
last 24 hours
0
last 7 days
4
last 30 days
3 before9 after
this quake
Strongest of the sequence2.3

How often does it happen here?

about every ~5 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 789 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 · 36 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 · 16 km from here
VII-VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
19675.3
Monti Nebrodi earthquake
31 October 1967 · 15 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 58 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

0.6
5 km South-East of Scillato
25 km West · 13 km
5 years ago
13 Sept 2021, 15:00
1.6
2 km East of Cerami
25 km East · 35 km
5 years ago
8 Sept 2021, 22:42
2.3
2 km South-East of Geraci Siculo
7 km South-West · 5 km
5 years ago
28 Sept 2021, 23:40
1.4
4 km South of Reitano
12 km North-East · 29 km
5 years ago
29 Sept 2021, 14:20
0.9
8 km North-East of Gangi
6 km South-East · 10 km
5 years ago
1 Oct 2021, 11:44
1.9
5 km East of Geraci Siculo
2 km South-West · 10 km
5 years ago
3 Oct 2021, 07:07
1.3
2 km East of Geraci Siculo
6 km South-West · 10 km
5 years ago
3 Oct 2021, 11:58
1.4
3 km South of Caronia
21 km East · 10 km
5 years ago
26 Aug 2021, 18:43
1.6
7 km North of Sperlinga
9 km South-East · 5 km
5 years ago
6 Oct 2021, 02:36
1.5
5 years ago
8 Oct 2021, 17:51

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).