All earthquakes
1.8
very light
EARTHQUAKE DETAILS

4 km East of Piedimonte Etneo

131 months ago · 27 Sept, 08:38

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

4 km East of Piedimonte EtneoEarthquakes 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

57 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 ≈ 17 s

Animation sped up ~3× compared to reality.

  • Acireale
    18 km from the epicentre
    first tremor in ~3 s
    main shaking in ~5 s
  • Catania
    37 km from the epicentre
    first tremor in ~6 s
    main shaking in ~11 s
  • Messina
    55 km from the epicentre
    first tremor in ~9 s
    main shaking in ~16 s
  • Reggio di Calabria
    61 km from the epicentre
    first tremor in ~10 s
    main shaking in ~17 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?

Foreshock

In hindsight it was a foreshock: 130 months ago the same area had a stronger quake (M3.0). This can only be said after the fact — it was not predictable beforehand.

3.0
The mainshock
1 km North of Giarre
130 months ago · 9 Oct, 02:35
Activity in the area right now (30 km radius)
4
last 24 hours
39
last 7 days
74
last 30 days
16 before40 after
this quake
Strongest of the sequence3.0

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: 2570 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 · 21 km from here
IX-XCompletely destructive: most buildings are destroyed.
17866.1
Golfo di Patti earthquake
10 March 1786 · 37 km from here
IXDestructive: many buildings partly or fully collapse.
16135.6
Monti Nebrodi earthquake
25 August 1613 · 49 km from here
IXDestructive: many buildings partly or fully collapse.
17805.5
Sicilia nord-orientale earthquake
28 March 1780 · 17 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 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

1.4
2 km East of Milo
7 km South-West · 10 km
131 months ago
26 Sept, 03:25
1.8
2 km North-West of Maletto
23 km West · 29 km
130 months ago
28 Sept, 18:55
1.4
131 months ago
25 Sept, 22:06
1.4
3 km North-West of Roccella Valdemone
25 km North-West · 33 km
131 months ago
25 Sept, 11:31
1.7
0 km East of Viagrande
19 km South · 5 km
130 months ago
29 Sept, 21:37
1.7
130 months ago
30 Sept, 16:58
1.4
1 km South-West of Maletto
23 km West · 30 km
130 months ago
4 Oct, 23:50
1.5
5 km North of Maletto
23 km West · 30 km
131 months ago
19 Sept, 11:03
2.2
3 km North of Riposto
8 km South-East · 1 km
130 months ago
7 Oct, 15:22
1.9
2 km North-West of Giarre
8 km South · 7 km
130 months ago
9 Oct, 02:16

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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