All earthquakes
1.5
very light
EARTHQUAKE DETAILS

20 km South of Santa Marina Salina

120 months ago · 6 Aug, 11:53

A very light earthquake, probably not felt by people. At this depth the shaking is felt, but rarely causes damage.

Stronger than 68% of Italian events in the past year

Where

20 km South of Santa Marina SalinaEarthquakes in the province of MessinaEarthquakes in Sicilia

Volcanic area: Aeolian Islands

Here the ground shakes mostly because of moving magma and underground fluids, not colliding plates: events are typically shallow, frequent and organised in swarms. This activity is constantly monitored by INGV.

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.

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
    57 km from the epicentre
    first tremor in ~10 s
    main shaking in ~17 s
  • Reggio di Calabria
    77 km from the epicentre
    first tremor in ~13 s
    main shaking in ~22 s
  • Acireale
    86 km from the epicentre
    first tremor in ~14 s
    main shaking in ~25 s
  • Catania
    101 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

11 km
medium depth
1.2 times the height of Mount Everest

At this depth the shaking is felt, but rarely causes damage.

shallower than the area average (~37 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 (M3.3, 121 months ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

3.3
The mainshock
8 km North-West of Milazzo
121 months ago · 21 Jul, 06:45
Activity in the area right now (30 km radius)
1
last 24 hours
26
last 7 days
43
last 30 days
7 before15 after
this quake
Strongest of the sequence3.3

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: 1808 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 · 32 km from here
IXDestructive: many buildings partly or fully collapse.
19786.0
Golfo di Patti earthquake
15 April 1978 · 16 km from here
VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
16135.6
Monti Nebrodi earthquake
25 August 1613 · 30 km from here
IXDestructive: many buildings partly or fully collapse.
20045.4
Isole Eolie earthquake
5 May 2004 · 22 km from here
IVModerate: felt by many indoors; glasses and dishes rattle.

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

The closest seismic structure

Milazzo-Eolie

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

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
12 km North-West of Milazzo
25 km East · 113 km
120 months ago
5 Aug, 13:28
1.3
4 km North of Falcone
30 km South-East · 9 km
120 months ago
7 Aug, 15:24
2.2
7 km North-West of Milazzo
28 km East · 113 km
120 months ago
1 Aug, 02:16
2.1
15 km South of Santa Marina Salina
6 km North-West · 14 km
120 months ago
12 Aug, 03:55
2.1
16 km South of Santa Marina Salina
6 km North-West · 11 km
120 months ago
12 Aug, 04:12
2.4
18 km South of Santa Marina Salina
3 km North-West · 11 km
120 months ago
26 Jul, 16:15
2.1
8 km North-West of Milazzo
26 km East · 121 km
120 months ago
26 Jul, 15:16
1.7
2 km North of Oliveri
29 km South-East · 9 km
120 months ago
23 Jul, 07:09
1.9
120 months ago
20 Aug, 20:37
3.3
8 km North-West of Milazzo
28 km East · 116 km
121 months ago
21 Jul, 06:45

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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