All earthquakes
1.2
very light
EARTHQUAKE DETAILS

10 km North-East of Cerami

26 months ago · 21 Jul, 23:48

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 47% of Italian events in the past year

Where

10 km North-East of CeramiEarthquakes in the province of EnnaEarthquakes in Sicilia

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

15 events
Magnitude:lightweakmoderatestrong

The energy released

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

1.0kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×501 its energy
M0this quakeM2

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
    56 km from the epicentre
    first tremor in ~10 s
    main shaking in ~16 s
  • Catania
    58 km from the epicentre
    first tremor in ~10 s
    main shaking in ~17 s
  • Caltanissetta
    68 km from the epicentre
    first tremor in ~11 s
    main shaking in ~20 s
  • Gela
    88 km from the epicentre
    first tremor in ~15 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

9 km
shallow
1.1 times the height of Mount Everest

At only a few km deep the shaking is felt more sharply at the surface.

in line with the area average (~14 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: 25 months ago the same area had a stronger quake (M2.4). This can only be said after the fact — it was not predictable beforehand.

2.4
The mainshock
4 km South of San Marco d'Alunzio
25 months ago · 25 Jul, 16:27
Activity in the area right now (30 km radius)
1
last 24 hours
3
last 7 days
11
last 30 days
6 before8 after
this quake
Strongest of the sequence2.4

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: 2335 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.

17866.1
Golfo di Patti earthquake
10 March 1786 · 46 km from here
IXDestructive: many buildings partly or fully collapse.
18235.8
Sicilia settentrionale earthquake
5 March 1823 · 42 km from here
VIII-IXDestructive: many buildings partly or fully collapse.
16135.6
Monti Nebrodi earthquake
25 August 1613 · 33 km from here
IXDestructive: many buildings partly or fully collapse.
17395.4
Monti Nebrodi earthquake
10 May 1739 · 29 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 42 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

1.7
8 km East of Capizzi
4 km North-West · 8 km
26 months ago
21 Jul, 20:29
1.7
2 km South-East of Maniace
17 km East · 35 km
26 months ago
21 Jul, 20:26
2.2
3 km East of Capizzi
6 km West · 19 km
26 months ago
21 Jul, 12:12
1.7
4 km South-West of Randazzo
19 km East · 6 km
25 months ago
24 Jul, 09:27
2.4
4 km South of San Marco d'Alunzio
21 km North-East · 139 km
25 months ago
25 Jul, 16:27
2.0
26 months ago
13 Jul, 21:28
2.3
3 km North-East of Agira
26 km South · 37 km
26 months ago
10 Jul, 11:22
1.8
2 km South-West of San Teodoro
9 km South-East · 30 km
25 months ago
4 Aug, 02:42
1.3
6 km South of San Teodoro
12 km South-East · 10 km
25 months ago
4 Aug, 02:44
1.3
6 km North of Nicosia
23 km West · 9 km
25 months ago
5 Aug, 04:46

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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