All earthquakes
1.6
very light
EARTHQUAKE DETAILS

13 km South-East of Alì Terme

73 months ago · 11 Sept, 08:29

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 74% of Italian events in the past year

Where

13 km South-East of Alì TermeEarthquakes 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

8 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 ≈ 20 s

Animation sped up ~4× compared to reality.

  • Reggio di Calabria
    23 km from the epicentre
    first tremor in ~4 s
    main shaking in ~7 s
  • Messina
    27 km from the epicentre
    first tremor in ~5 s
    main shaking in ~8 s
  • Acireale
    49 km from the epicentre
    first tremor in ~8 s
    main shaking in ~14 s
  • Catania
    69 km from the epicentre
    first tremor in ~12 s
    main shaking in ~20 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
1 times the height of Mount Everest

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

shallower than the area average (~17 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: 72 months ago the same area had a stronger quake (M2.5). This can only be said after the fact — it was not predictable beforehand.

2.5
The mainshock
14 km South-West of Melito di Porto Salvo
72 months ago · 7 Oct, 15:13
Activity in the area right now (30 km radius)
0
last 24 hours
1
last 7 days
4
last 30 days
3 before4 after
this quake
Strongest of the sequence2.5

How often does it happen here?

about every ~3 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 1583 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 · 25 km from here
XICatastrophic: very few buildings remain standing; landslides and ground cracks.
17866.1
Golfo di Patti earthquake
10 March 1786 · 49 km from here
IXDestructive: many buildings partly or fully collapse.
18946.1
Calabria meridionale earthquake
16 November 1894 · 47 km from here
IXDestructive: many buildings partly or fully collapse.
19076.0
Aspromonte earthquake
23 October 1907 · 42 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

Aspromonte-Peloritani

The epicentre sits above this source area: the deep structure where this area's earthquakes can originate.

estimated maximum magnitude 7.3between 2 and 13 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

1.2
6 km South-East of Taormina
24 km South-West · 22 km
73 months ago
7 Sept, 23:42
1.6
73 months ago
21 Aug, 06:42
1.6
72 months ago
6 Oct, 09:47
2.5
72 months ago
7 Oct, 15:13
0.7
3 km South-West of Bagaladi
25 km East · 10 km
74 months ago
14 Aug, 05:09
1.6
72 months ago
9 Oct, 22:29
2.2
72 months ago
11 Oct, 04:28

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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