All earthquakes
1.5
very light
EARTHQUAKE DETAILS

12 km North of Villafranca Tirrena

23 months ago · 20 Oct, 12:54

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 68% of Italian events in the past year

Where

12 km North of Villafranca TirrenaEarthquakes 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

18 events
Magnitude:lightweakmoderatestrong

The energy released

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

2.7kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×178 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
    17 km from the epicentre
    first tremor in ~3 s
    main shaking in ~5 s
  • Reggio di Calabria
    36 km from the epicentre
    first tremor in ~6 s
    main shaking in ~10 s
  • Acireale
    80 km from the epicentre
    first tremor in ~14 s
    main shaking in ~23 s
  • Catania
    100 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

9 km
shallow

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

shallower than the area average (~41 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 (M2.5, 23 months ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

2.5
The mainshock
Tirreno Meridionale [Mare]
23 months ago · 4 Oct, 12:46
Activity in the area right now (30 km radius)
0
last 24 hours
5
last 7 days
13
last 30 days
7 before10 after
this quake
Strongest of the sequence2.5

How often does it happen here?

about every ~2 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 1921 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.

19087.1
Stretto di Messina earthquake
28 December 1908 · 30 km from here
XICatastrophic: very few buildings remain standing; landslides and ground cracks.
17837.1
Calabria meridionale earthquake
5 February 1783 · 48 km from here
XICatastrophic: very few buildings remain standing; landslides and ground cracks.
17866.1
Golfo di Patti earthquake
10 March 1786 · 43 km from here
IXDestructive: many buildings partly or fully collapse.
18946.1
Calabria meridionale earthquake
16 November 1894 · 39 km from here
IXDestructive: many buildings partly or fully collapse.

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

The closest seismic structure

Bagnara-Bovalino

The epicentre lies about 16 km from Bagnara-Bovalino, one of the seismic structures mapped by INGV geologists.

estimated maximum magnitude 7.1between 3 and 12 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

1.6
12 km North of Villafranca Tirrena
1 km South-West · 10 km
23 months ago
20 Oct, 09:31
1.9
12 km North of Milazzo
17 km West · 113 km
23 months ago
15 Oct, 19:46
1.8
22 months ago
25 Oct, 22:13
1.1
22 months ago
27 Oct, 10:20
1.9
22 months ago
29 Oct, 01:50
0.6
10 km West of Milazzo
28 km West · 4 km
22 months ago
29 Oct, 11:03
0.4
3 km South-East of Milazzo
20 km South-West · 9 km
23 months ago
10 Oct, 17:41
2.3
23 months ago
10 Oct, 03:35
1.3
3 km North-East of Spadafora
11 km South · 62 km
22 months ago
31 Oct, 03:14
2.5
Tirreno Meridionale [Mare]
22 km North · 119 km
23 months ago
4 Oct, 12:46

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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