All earthquakes
1.4
very light
EARTHQUAKE DETAILS

4 km East of Gagliano Castelferrato

119 months ago · 31 Aug, 05:22

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

Stronger than 62% of Italian events in the past year

Where

4 km East of Gagliano CastelferratoEarthquakes 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

6 events
Magnitude:lightweakmoderatestrong

The energy released

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

1.9kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×251 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 ≈ 21 s

Animation sped up ~4× compared to reality.

  • Catania
    49 km from the epicentre
    first tremor in ~8 s
    main shaking in ~14 s
  • Acireale
    53 km from the epicentre
    first tremor in ~9 s
    main shaking in ~15 s
  • Caltanissetta
    57 km from the epicentre
    first tremor in ~10 s
    main shaking in ~17 s
  • Gela
    72 km from the epicentre
    first tremor in ~12 s
    main shaking in ~21 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
1.2 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 (M1.8, 120 months ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

1.8
The mainshock
1 km East of Capizzi
120 months ago · 11 Aug, 21:50
Activity in the area right now (30 km radius)
0
last 24 hours
18
last 7 days
29
last 30 days
4 before1 after
this quake
Strongest of the sequence1.8

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: 2232 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.

16135.6
Monti Nebrodi earthquake
25 August 1613 · 49 km from here
IXDestructive: many buildings partly or fully collapse.
17395.4
Monti Nebrodi earthquake
10 May 1739 · 45 km from here
VIII-IXDestructive: many buildings partly or fully collapse.
18185.3
Monti Madonie earthquake
8 September 1818 · 45 km from here
VII-VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
19675.3
Monti Nebrodi earthquake
31 October 1967 · 22 km from here
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 lies about 28 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

1.4
119 months ago
31 Aug, 04:56
1.5
119 months ago
31 Aug, 03:50
1.6
2 km South-East of Caronia
29 km North · 6 km
119 months ago
27 Aug, 05:09
1.3
3 km South-West of Alcara li Fusi
29 km North-East · 8 km
119 months ago
4 Sept, 19:49
1.8
1 km East of Capizzi
18 km North-West · 33 km
120 months ago
11 Aug, 21:50

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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