All earthquakes
1.6
very light
EARTHQUAKE DETAILS

6 km North-West of Ragalna

108 months ago · 6 Aug, 07:29

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

Stronger than 73% of Italian events in the past year

Where

6 km North-West of RagalnaEarthquakes 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.

3.8kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×126 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 ≈ 25 s

Animation sped up ~5× compared to reality.

  • Acireale
    23 km from the epicentre
    first tremor in ~6 s
    main shaking in ~10 s
  • Catania
    27 km from the epicentre
    first tremor in ~6 s
    main shaking in ~11 s
  • Messina
    75 km from the epicentre
    first tremor in ~13 s
    main shaking in ~23 s
  • Siracusa
    82 km from the epicentre
    first tremor in ~14 s
    main shaking in ~25 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

25 km
medium depth
2.8 times the height of Mount Everest

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

deeper 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: 107 months ago the same area had a stronger quake (M3.1). This can only be said after the fact — it was not predictable beforehand.

3.1
The mainshock
5 km North-West of San Pietro Clarenza
107 months ago · 25 Aug, 23:57
Activity in the area right now (30 km radius)
21
last 24 hours
27
last 7 days
67
last 30 days
14 before105 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: 2491 events in the last 11 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 · 22 km from here
IX-XCompletely destructive: most buildings are destroyed.
17866.1
Golfo di Patti earthquake
10 March 1786 · 45 km from here
IXDestructive: many buildings partly or fully collapse.
16985.7
Monti Iblei settentrionali earthquake
1 January 1698 · 47 km from here
VII-VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
16135.6
Monti Nebrodi earthquake
25 August 1613 · 48 km from here
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 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

1.5
5 km South of Maletto
6 km North · 27 km
108 months ago
5 Aug, 03:53
2.0
2 km North-East of Aci Castello
26 km South-East · 7 km
108 months ago
7 Aug, 11:05
1.3
4 km South-East of Moio Alcantara
22 km North-East · 25 km
108 months ago
8 Aug, 21:46
1.7
5 km South of Moio Alcantara
21 km North-East · 25 km
108 months ago
9 Aug, 03:10
1.9
2 km South-West of Viagrande
17 km South-East · 7 km
108 months ago
11 Aug, 21:34
1.2
5 km East of Castiglione di Sicilia
26 km North-East · 20 km
108 months ago
29 Jul, 02:54
3.0
108 months ago
27 Jul, 10:30
1.8
5 km South-West of Pedara
12 km South-East · 6 km
107 months ago
17 Aug, 14:18
1.4
7 km East of San Teodoro
19 km North-West · 10 km
107 months ago
18 Aug, 22:50
1.2
6 km South-East of Maletto
8 km North · 31 km
107 months ago
19 Aug, 00:42

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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