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2.5
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EARTHQUAKE DETAILS

21 km North of Villafranca Tirrena

103 months ago · 27 Dec, 04:35

A light earthquake, rarely felt by people. Being deep, it is felt less at the surface.

Stronger than 95% of Italian events in the past year

Where

21 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

23 events
Magnitude:lightweakmoderatestrong

The energy released

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

85kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×5.6 its energy
M2this quakeM4

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 ≈ 47 s

Animation sped up ~9× compared to reality.

  • Messina
    24 km from the epicentre
    first tremor in ~23 s
    main shaking in ~39 s
  • Reggio di Calabria
    41 km from the epicentre
    first tremor in ~23 s
    main shaking in ~40 s
  • Acireale
    89 km from the epicentre
    first tremor in ~27 s
    main shaking in ~46 s
  • Lamezia Terme
    96 km from the epicentre
    first tremor in ~27 s
    main shaking in ~47 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

133 km
deep
15 times the height of Mount Everest

Being deep, it is felt less at the surface.

deeper than the area average (~48 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: 103 months ago the same area had a stronger quake (M3.1). This can only be said after the fact — it was not predictable beforehand.

3.1
The mainshock
23 km North of Villafranca Tirrena
103 months ago · 5 Jan, 07:25
Activity in the area right now (30 km radius)
0
last 24 hours
8
last 7 days
28
last 30 days
10 before12 after
this quake
Strongest of the sequence3.1

How often does it happen here?

about every ~8 days

Within 50 km of this epicentre, a magnitude ≥ 2.5 earthquake has occurred on average this often: 512 events in the last 11 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 · 36 km from here
XICatastrophic: very few buildings remain standing; landslides and ground cracks.
17837.1
Calabria meridionale earthquake
5 February 1783 · 47 km from here
XICatastrophic: very few buildings remain standing; landslides and ground cracks.
17866.1
Golfo di Patti earthquake
10 March 1786 · 50 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 14 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

2.4
Tirreno Meridionale [Mare]
6 km North-East · 147 km
103 months ago
23 Dec, 23:01
2.7
24 km West of Ricadi
21 km North-East · 157 km
103 months ago
23 Dec, 20:52
1.9
103 months ago
31 Dec, 03:15
1.6
103 months ago
1 Jan, 11:33
1.2
3 km North-East of Villa San Giovanni
28 km South-East · 10 km
103 months ago
21 Dec, 15:25
2.5
Tirreno Meridionale [Mare]
13 km West · 131 km
103 months ago
2 Jan, 08:17
1.9
Tirreno Meridionale [Mare]
19 km North-East · 136 km
103 months ago
19 Dec, 23:19
3.1
103 months ago
5 Jan, 07:25
1.8
103 months ago
16 Dec, 03:26
2.1
Tirreno Meridionale [Mare]
11 km North-East · 135 km
103 months ago
11 Jan, 12:28

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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