All earthquakes
2.3
light
EARTHQUAKE DETAILS

1 km South-East of Aci Sant'Antonio

64 months ago · 25 May, 05:29

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

1 km South-East of Aci Sant'AntonioEarthquakes 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.

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 ≈ 21 s

Animation sped up ~4× compared to reality.

  • Acireale
    4 km from the epicentre
    first tremor in ~2 s
    main shaking in ~3 s
  • Catania
    17 km from the epicentre
    first tremor in ~3 s
    main shaking in ~6 s
  • Siracusa
    69 km from the epicentre
    first tremor in ~12 s
    main shaking in ~20 s
  • Messina
    73 km from the epicentre
    first tremor in ~12 s
    main shaking in ~21 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.

in line with 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.

3.1
The mainshock
4 km South of Piedimonte Etneo
65 months ago · 8 May, 20:13
Activity in the area right now (30 km radius)
0
last 24 hours
6
last 7 days
19
last 30 days
170 before16 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: 2228 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.

15426.7
Sicilia sud-orientale earthquake
10 December 1542 · 47 km from here
XCompletely destructive: most buildings are destroyed.
11696.5
Sicilia sud-orientale earthquake
4 February 1169 · 47 km from here
XCompletely destructive: most buildings are destroyed.
18186.3
Catanese earthquake
20 February 1818 · 2 km from here
IX-XCompletely destructive: most buildings are destroyed.
16985.7
Monti Iblei settentrionali earthquake
1 January 1698 · 46 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 sits above this source area: the deep structure where this area's earthquakes can originate.

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

1.9
64 months ago
24 May, 20:17
1.8
5 km North-West of Belpasso
19 km West · 4 km
64 months ago
22 May, 09:48
1.2
3 km South-West of Sant'Alfio
15 km North-West · 3 km
64 months ago
28 May, 01:19
1.5
7 km North-East of Adrano
21 km North-West · 8 km
64 months ago
21 May, 02:24
1.8
7 km North-East of Adrano
22 km North-West · 9 km
64 months ago
21 May, 01:02
2.0
8 km South-East of Maletto
21 km North-West · 9 km
64 months ago
29 May, 23:27
1.2
3 km South-West of Sant'Alfio
15 km North-West · 6 km
64 months ago
19 May, 08:02
1.1
7 km East of Maletto
25 km North-West · 30 km
64 months ago
31 May, 05:42
1.1
8 km East of Maletto
26 km North-West · 29 km
64 months ago
31 May, 05:42
2.0
3 km West of Gaggi
28 km North · 24 km
64 months ago
31 May, 14:03

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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