All earthquakes
2.3
light
EARTHQUAKE DETAILS

M2.3 offshore earthquake

4 years ago · 11 Dec 2021, 06:59

A light earthquake, rarely felt by people. At only a few km deep the shaking is felt more sharply at the surface.

Stronger than 93% of Italian events in the past year

Where

Nearest Italian town: Capo d'Orlando (ME)Earthquakes in the province of MessinaEarthquakes in Sicilia

Epicentre at sea

The epicentre is at sea: for the same magnitude, the shaking is felt less on land, because the energy fades along the way before reaching the coast.

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

16 events
Magnitude:lightweakmoderatestrong

The energy released

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

43kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×11 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.

  • Messina
    81 km from the epicentre
    first tremor in ~14 s
    main shaking in ~23 s
  • Acireale
    95 km from the epicentre
    first tremor in ~16 s
    main shaking in ~27 s
  • Reggio di Calabria
    101 km from the epicentre
    first tremor in ~17 s
    main shaking in ~29 s
  • Bagheria
    103 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

8 km
shallow

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

shallower than the area average (~23 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, 4 years ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

2.8
The mainshock
Isole Eolie (Messina)
4 years ago · 4 Dec 2021, 21:40
Activity in the area right now (30 km radius)
0
last 24 hours
5
last 7 days
17
last 30 days
12 before3 after
this quake
Strongest of the sequence2.8

How often does it happen here?

about every ~4 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 1096 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.

17866.1
Golfo di Patti earthquake
10 March 1786 · 47 km from here
IXDestructive: many buildings partly or fully collapse.
19786.0
Golfo di Patti earthquake
15 April 1978 · 42 km from here
VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
18235.8
Sicilia settentrionale earthquake
5 March 1823 · 31 km from here
VIII-IXDestructive: many buildings partly or fully collapse.
19805.7
Tirreno meridionale earthquake
28 May 1980 · 32 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

Southern Tyrrhenian

The epicentre lies about 7 km from Southern Tyrrhenian, one of the seismic structures mapped by INGV geologists.

estimated maximum magnitude 8.2between 2 and 18 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

1.8
4 years ago
7 Dec 2021, 09:31
2.2
Isole Eolie (Messina)
21 km North-West · 6 km
4 years ago
6 Dec 2021, 06:45
2.8
Isole Eolie (Messina)
27 km North-West · 16 km
4 years ago
4 Dec 2021, 21:40
2.4
7 km West of Leni
25 km North-East · 7 km
4 years ago
2 Dec 2021, 06:41
2.2
17 km West of Leni
22 km North · 11 km
4 years ago
21 Dec 2021, 00:33
2.0
17 km West of Leni
18 km North · 9 km
4 years ago
21 Dec 2021, 00:34
1.6
4 years ago
25 Nov 2021, 21:51
1.4
Costa Siciliana nord-orientale (Messina)
1 km West · 9 km
4 years ago
25 Nov 2021, 19:38
1.6
4 years ago
19 Nov 2021, 06:49
1.5
8 km South of Santa Marina Salina
25 km North-East · 9 km
4 years ago
19 Nov 2021, 01:36

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).