All earthquakes
1.9
very light
EARTHQUAKE DETAILS

6 km North-East of Gagliano Castelferrato

88 months ago · 31 Mar, 23:59

A very light earthquake, probably not felt by people. Being deep, it is felt less at the surface.

Stronger than 85% of Italian events in the past year

Where

6 km North-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

61 events
Magnitude:lightweakmoderatestrong

The energy released

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

11kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×45 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.

  • Catania
    49 km from the epicentre
    first tremor in ~10 s
    main shaking in ~17 s
  • Acireale
    52 km from the epicentre
    first tremor in ~10 s
    main shaking in ~17 s
  • Caltanissetta
    60 km from the epicentre
    first tremor in ~11 s
    main shaking in ~19 s
  • Gela
    75 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

31 km
deep
3.5 times the height of Mount Everest

Being deep, it is felt less at the surface.

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?

Foreshock

In hindsight it was a foreshock: 87 months ago the same area had a stronger quake (M2.5). This can only be said after the fact — it was not predictable beforehand.

2.5
The mainshock
2 km South-East of Randazzo
87 months ago · 29 Apr, 03:36
Activity in the area right now (30 km radius)
0
last 24 hours
18
last 7 days
29
last 30 days
32 before33 after
this quake
Strongest of the sequence2.5

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: 2310 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 · 46 km from here
IXDestructive: many buildings partly or fully collapse.
17395.4
Monti Nebrodi earthquake
10 May 1739 · 42 km from here
VIII-IXDestructive: many buildings partly or fully collapse.
18185.3
Monti Madonie earthquake
8 September 1818 · 46 km from here
VII-VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
19675.3
Monti Nebrodi earthquake
31 October 1967 · 21 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 30 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

2.4
4 km South-East of Troina
7 km East · 28 km
88 months ago
1 Apr, 03:43
1.1
6 km North-East of Bronte
28 km North-East · 9 km
88 months ago
31 Mar, 11:25
1.9
2 km West of Biancavilla
25 km East · 14 km
88 months ago
2 Apr, 06:51
1.8
3 km South of Troina
6 km East · 25 km
88 months ago
28 Mar, 18:48
2.3
2 km South-West of Troina
5 km East · 27 km
88 months ago
28 Mar, 18:42
1.6
3 km South-West of Troina
4 km East · 29 km
88 months ago
27 Mar, 09:13
1.5
2 km South of Troina
6 km East · 26 km
88 months ago
27 Mar, 07:54
1.9
3 km South-West of Troina
4 km East · 30 km
88 months ago
27 Mar, 07:50
2.4
4 km South-West of Troina
2 km East · 31 km
88 months ago
27 Mar, 07:26
1.6
88 months ago
27 Mar, 07:20

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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