All earthquakes
2.4
light
EARTHQUAKE DETAILS

1 km East of Riposto

123 months ago · 27 Apr, 19:49

A light earthquake, rarely felt by people. At only a few km deep the shaking is felt more sharply at the surface.

Stronger than 94% of Italian events in the past year

Where

1 km East of RipostoEarthquakes 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

22 events
Magnitude:lightweakmoderatestrong

The energy released

How much energy this quake unleashed, translated into everyday comparisons.

60kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×7.9 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 ≈ 18 s

Animation sped up ~3× compared to reality.

  • Acireale
    8 km from the epicentre
    first tremor in ~1 s
    main shaking in ~2 s
  • Catania
    29 km from the epicentre
    first tremor in ~5 s
    main shaking in ~8 s
  • Messina
    61 km from the epicentre
    first tremor in ~10 s
    main shaking in ~18 s
  • Reggio di Calabria
    64 km from the epicentre
    first tremor in ~11 s
    main shaking in ~18 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

2 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?

Aftershock

It is an aftershock: it follows a stronger quake (M3.1, 124 months ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

3.1
The mainshock
18 km East of Aci Castello
124 months ago · 30 Mar, 13:16
Activity in the area right now (30 km radius)
2
last 24 hours
7
last 7 days
22
last 30 days
16 before5 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: 2315 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 · 12 km from here
IX-XCompletely destructive: most buildings are destroyed.
17866.1
Golfo di Patti earthquake
10 March 1786 · 48 km from here
IXDestructive: many buildings partly or fully collapse.
19905.6
Sicilia sud-orientale earthquake
13 December 1990 · 48 km from here
VII-VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
17805.5
Sicilia nord-orientale earthquake
28 March 1780 · 21 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

1.5
10 km South of Aci Castello
25 km South · 7 km
123 months ago
27 Apr, 07:09
2.4
1 km East of Giarre
3 km West · 6 km
123 months ago
27 Apr, 01:56
1.5
10 km West of Castiglione di Sicilia
28 km North-West · 18 km
123 months ago
24 Apr, 05:51
1.5
3 km North-East of Ragalna
20 km West · 17 km
124 months ago
20 Apr, 08:09
1.5
2 km North-East of Ragalna
22 km West · 16 km
124 months ago
20 Apr, 07:28
1.4
3 km West of Ragalna
26 km West · 13 km
124 months ago
20 Apr, 03:25
1.6
2 km North-West of Ragalna
24 km West · 17 km
124 months ago
20 Apr, 02:44
1.2
3 km North of Ragalna
22 km West · 18 km
124 months ago
19 Apr, 23:05
2.1
6 km North of Belpasso
25 km West · 5 km
123 months ago
8 May, 18:35
2.1
123 months ago
8 May, 22:17

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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