All earthquakes
1.9
very light
EARTHQUAKE DETAILS

1 km North-West of Sant'Alfio

98 months ago · 3 Jun, 13:28

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 85% of Italian events in the past year

Where

1 km North-West of Sant'AlfioEarthquakes in the province of CataniaEarthquakes in Sicilia

Volcanic area: Mount Etna

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

61 events
Magnitude:lightweakmoderatestrong

The energy released

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

11kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×45 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.

  • Acireale
    17 km from the epicentre
    first tremor in ~3 s
    main shaking in ~5 s
  • Catania
    33 km from the epicentre
    first tremor in ~6 s
    main shaking in ~10 s
  • Messina
    61 km from the epicentre
    first tremor in ~10 s
    main shaking in ~18 s
  • Reggio di Calabria
    68 km from the epicentre
    first tremor in ~11 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

7 km
shallow

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

shallower than the area average (~13 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?

Seismic swarm

It is part of a seismic swarm: many closely spaced quakes in the same area, with no dominant shock. A typical, well-known behaviour of some Italian areas.

3.4
The mainshock
1 km West of Giarre
98 months ago · 2 Jun, 09:40
Activity in the area right now (30 km radius)
5
last 24 hours
31
last 7 days
63
last 30 days
94 before33 after
this quake
Strongest of the sequence3.4

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: 2627 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.

18186.3
Catanese earthquake
20 February 1818 · 19 km from here
IX-XCompletely destructive: most buildings are destroyed.
17866.1
Golfo di Patti earthquake
10 March 1786 · 38 km from here
IXDestructive: many buildings partly or fully collapse.
16135.6
Monti Nebrodi earthquake
25 August 1613 · 47 km from here
IXDestructive: many buildings partly or fully collapse.
17805.5
Sicilia nord-orientale earthquake
28 March 1780 · 24 km from here
VII-VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.

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

The closest seismic structure

Gela-Catania

The epicentre lies about 14 km from Gela-Catania, one of the seismic structures mapped by INGV geologists.

estimated maximum magnitude 7.1between 3 and 10 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

2.3
3 km West of Sant'Alfio
2 km West · 8 km
98 months ago
3 Jun, 13:04
2.2
2 km West of Sant'Alfio
2 km West · 9 km
98 months ago
3 Jun, 13:03
1.8
2 km West of Sant'Alfio
2 km West · 8 km
98 months ago
3 Jun, 13:02
1.9
2 km West of Sant'Alfio
2 km West · 7 km
98 months ago
3 Jun, 13:02
2.0
8 km East of Maletto
8 km West · 22 km
98 months ago
3 Jun, 14:25
1.6
5 km West of Sant'Alfio
5 km South-West · 9 km
98 months ago
3 Jun, 18:00
1.3
8 km South of Maletto
13 km West · 8 km
98 months ago
3 Jun, 05:24
1.8
5 km West of Sant'Alfio
4 km West · 10 km
98 months ago
3 Jun, 03:44
1.2
8 km North-East of Adrano
12 km West · 8 km
98 months ago
3 Jun, 02:33
1.6
1 km North-West of Santa Venerina
10 km South-East · 9 km
98 months ago
2 Jun, 20:16

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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