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2.3
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EARTHQUAKE DETAILS

M2.3 earthquake · 2 km West of Merì (ME)

5 years ago · 4 Jun 2021, 11:44

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

2 km West of MerìEarthquakes 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

61 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 ≈ 22 s

Animation sped up ~4× compared to reality.

  • Messina
    25 km from the epicentre
    first tremor in ~4 s
    main shaking in ~8 s
  • Reggio di Calabria
    43 km from the epicentre
    first tremor in ~7 s
    main shaking in ~13 s
  • Acireale
    59 km from the epicentre
    first tremor in ~10 s
    main shaking in ~17 s
  • Catania
    78 km from the epicentre
    first tremor in ~13 s
    main shaking in ~22 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

7 km
shallow

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

shallower than the area average (~28 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 (M3.1). This can only be said after the fact — it was not predictable beforehand.

3.1
The mainshock
10 km North-West of Terme Vigliatore
5 years ago · 16 Jun 2021, 11:15
Activity in the area right now (30 km radius)
2
last 24 hours
16
last 7 days
57
last 30 days
27 before122 after
this quake
Strongest of the sequence3.1

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: 2586 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 · 40 km from here
XICatastrophic: very few buildings remain standing; landslides and ground cracks.
17866.1
Golfo di Patti earthquake
10 March 1786 · 19 km from here
IXDestructive: many buildings partly or fully collapse.
19786.0
Golfo di Patti earthquake
15 April 1978 · 29 km from here
VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
17495.8
Messina earthquake
August 1749 · 29 km from here
VIII-IXDestructive: many buildings partly or fully collapse.

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

The closest seismic structure

Milazzo-Eolie

The epicentre lies about 3 km from Milazzo-Eolie, one of the seismic structures mapped by INGV geologists.

estimated maximum magnitude 6.9between 1 and 25 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

2.0
17 km North of Villafranca Tirrena
28 km North-East · 117 km
5 years ago
5 Jun 2021, 05:04
1.8
17 km North of Villafranca Tirrena
28 km North-East · 117 km
5 years ago
5 Jun 2021, 22:28
1.4
5 km North-East of Patti
17 km West · 8 km
5 years ago
5 Jun 2021, 22:55
0.8
1 km North-West of Tripi
17 km South-West · 7 km
5 years ago
6 Jun 2021, 02:31
1.3
2 km South-West of San Piero Patti
28 km South-West · 6 km
5 years ago
6 Jun 2021, 17:11
2.9
18 km North of Milazzo
26 km North · 166 km
5 years ago
8 Jun 2021, 15:35
1.5
14 km West of Milazzo
16 km North-West · 12 km
5 years ago
30 May 2021, 20:13
2.4
8 km North-West of Milazzo
15 km North · 116 km
5 years ago
10 Jun 2021, 05:47
1.7
1 km West of Santa Teresa di Riva
23 km South-East · 38 km
5 years ago
10 Jun 2021, 18:15
1.1
3 km North of Francavilla di Sicilia
23 km South-West · 9 km
5 years ago
11 Jun 2021, 03:46

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).