All earthquakes
1.8
very light
EARTHQUAKE DETAILS

2 km North of Zafferana Etnea

87 months ago · 1 May, 10:11

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 82% of Italian events in the past year

Where

2 km North of Zafferana EtneaEarthquakes 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.

7.6kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×63 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
    13 km from the epicentre
    first tremor in ~3 s
    main shaking in ~4 s
  • Catania
    28 km from the epicentre
    first tremor in ~5 s
    main shaking in ~8 s
  • Messina
    65 km from the epicentre
    first tremor in ~11 s
    main shaking in ~19 s
  • Reggio di Calabria
    71 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

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.

3.3
The mainshock
4 km West of Fiumefreddo di Sicilia
87 months ago · 27 Apr, 02:44
Activity in the area right now (30 km radius)
9
last 24 hours
30
last 7 days
63
last 30 days
71 before55 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: 2530 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 · 14 km from here
IX-XCompletely destructive: most buildings are destroyed.
17866.1
Golfo di Patti earthquake
10 March 1786 · 43 km from here
IXDestructive: many buildings partly or fully collapse.
17805.5
Sicilia nord-orientale earthquake
28 March 1780 · 27 km from here
VII-VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
18485.5
Golfo di Catania earthquake
11 January 1848 · 36 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

Gela-Catania

The epicentre lies about 10 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

1.0
3 km North-West of Zafferana Etnea
1 km North-West · 4 km
87 months ago
1 May, 10:53
1.5
13 km East of Riposto
24 km East · 9 km
87 months ago
1 May, 07:05
1.9
1 km North-East of Randazzo
23 km West · 32 km
87 months ago
1 May, 05:20
1.8
1 km South-West of Milo
2 km East · 8 km
87 months ago
30 Apr, 20:30
1.4
2 km North of Ragalna
11 km West · 17 km
87 months ago
2 May, 23:14
2.2
1 km West of Milo
2 km North-East · 8 km
87 months ago
29 Apr, 15:01
2.4
3 km North-West of Zafferana Etnea
1 km North-West · 9 km
87 months ago
29 Apr, 15:01
1.4
3 km South-East of Randazzo
21 km West · 31 km
87 months ago
29 Apr, 06:55
1.6
3 km South-West of Randazzo
24 km West · 32 km
87 months ago
29 Apr, 04:48
1.9
2 km South-West of Randazzo
23 km West · 33 km
87 months ago
29 Apr, 04:15

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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