All earthquakes
1.1
very light
EARTHQUAKE DETAILS

3 km North-East of Troina

4 days ago · 21 Aug, 09:56

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

Stronger than 39% of Italian events in the past year

Where

3 km North-East of TroinaEarthquakes 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

13 events
Magnitude:lightweakmoderatestrong

The energy released

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

0.7kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×708 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 ≈ 24 s

Animation sped up ~4× compared to reality.

  • Acireale
    46 km from the epicentre
    first tremor in ~8 s
    main shaking in ~13 s
  • Catania
    46 km from the epicentre
    first tremor in ~8 s
    main shaking in ~14 s
  • Caltanissetta
    69 km from the epicentre
    first tremor in ~12 s
    main shaking in ~20 s
  • Gela
    83 km from the epicentre
    first tremor in ~14 s
    main shaking in ~24 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

10 km
medium depth
1.1 times the height of Mount Everest

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

in line with 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 (M2.9, 19 days ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

2.9
The mainshock
6 km North of Troina
19 days ago · 6 Aug, 03:46
Activity in the area right now (30 km radius)
0
last 24 hours
2
last 7 days
11
last 30 days
12 before0 after
nowthis quake
Strongest of the sequence2.9

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: 2552 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 · 45 km from here
IX-XCompletely destructive: most buildings are destroyed.
17866.1
Golfo di Patti earthquake
10 March 1786 · 46 km from here
IXDestructive: many buildings partly or fully collapse.
16135.6
Monti Nebrodi earthquake
25 August 1613 · 39 km from here
IXDestructive: many buildings partly or fully collapse.
17395.4
Monti Nebrodi earthquake
10 May 1739 · 35 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 31 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

1.2
5 km South-East of Cerami
12 km West · 7 km
5 days ago
20 Aug, 05:46
1.6
3 km West of Cesarò
9 km North · 31 km
14 days ago
11 Aug, 02:56
0.8
1 km West of Tortorici
27 km North-East · 8 km
17 days ago
8 Aug, 08:19
1.5
3 km South-East of Floresta
29 km North-East · 11 km
18 days ago
7 Aug, 04:24
2.2
5 km East of Cerami
11 km West · 10 km
19 days ago
6 Aug, 04:45
2.4
7 km North-West of Troina
8 km West · 38 km
19 days ago
6 Aug, 03:50
2.1
6 km South-West of Cerami
20 km West · 11 km
19 days ago
6 Aug, 03:47
2.9
6 km North of Troina
5 km North-West · 39 km
19 days ago
6 Aug, 03:46
1.7
8 km West of Sant'Alfio
28 km East · 0 km
22 days ago
3 Aug, 09:22
1.8
8 km South-East of Maletto
25 km East · 6 km
28 days ago
28 Jul, 03:23

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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