All earthquakes
1.6
very light
EARTHQUAKE DETAILS

3 km North of Ragalna

120 months ago · 1 Aug, 04:20

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

3 km North 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

20 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 ≈ 23 s

Animation sped up ~4× compared to reality.

  • Acireale
    19 km from the epicentre
    first tremor in ~4 s
    main shaking in ~8 s
  • Catania
    24 km from the epicentre
    first tremor in ~5 s
    main shaking in ~9 s
  • Messina
    75 km from the epicentre
    first tremor in ~13 s
    main shaking in ~22 s
  • Siracusa
    80 km from the epicentre
    first tremor in ~14 s
    main shaking in ~23 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

18 km
medium depth
2.1 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?

Aftershock

It is an aftershock: it follows a stronger quake (M2.7, 121 months ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

2.7
The mainshock
6 km South-East of Centuripe
121 months ago · 11 Jul, 13:16
Activity in the area right now (30 km radius)
2
last 24 hours
27
last 7 days
52
last 30 days
15 before4 after
this quake
Strongest of the sequence2.7

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: 2471 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 · 47 km from here
IXDestructive: many buildings partly or fully collapse.
16985.7
Monti Iblei settentrionali earthquake
1 January 1698 · 46 km from here
VII-VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
16245.6
Monti Iblei settentrionali earthquake
3 October 1624 · 50 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 11 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

1.9
2 km North-West of Ragalna
1 km South-West · 21 km
120 months ago
1 Aug, 04:15
1.5
6 km North of Ragalna
3 km North · 33 km
120 months ago
24 Jul, 17:30
2.1
5 km North of Ragalna
2 km North-West · 22 km
120 months ago
24 Jul, 16:52
1.8
3 km East of Troina
25 km West · 26 km
121 months ago
22 Jul, 13:41
1.9
6 km South-East of Ragalna
8 km South · 5 km
121 months ago
21 Jul, 15:02
1.7
3 km North-East of Randazzo
18 km North-West · 32 km
121 months ago
20 Jul, 10:37
1.7
4 km North-West of Maletto
18 km North-West · 30 km
121 months ago
20 Jul, 10:13
1.8
9 km South of Moio Alcantara
18 km North-East · 9 km
121 months ago
19 Jul, 10:10
1.8
10 km South of Moio Alcantara
17 km North-East · 19 km
121 months ago
19 Jul, 09:43
1.8
9 km South of Moio Alcantara
19 km North-East · 9 km
121 months ago
19 Jul, 07:27

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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