All earthquakes
1.6
very light
EARTHQUAKE DETAILS

4 km North-West of Mazzarrone

36 months ago · 11 Sept, 21:47

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

Stronger than 74% of Italian events in the past year

Where

4 km North-West of MazzarroneEarthquakes in the province of CataniaEarthquakes 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

10 events
Magnitude:lightweakmoderatestrong

The energy released

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

3.8kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×126 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 ≈ 11 s

Animation sped up ~2× compared to reality.

  • Vittoria
    18 km from the epicentre
    first tremor in ~4 s
    main shaking in ~7 s
  • Gela
    23 km from the epicentre
    first tremor in ~5 s
    main shaking in ~8 s
  • Ragusa
    24 km from the epicentre
    first tremor in ~5 s
    main shaking in ~9 s
  • Modica
    35 km from the epicentre
    first tremor in ~6 s
    main shaking in ~11 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

17 km
medium depth
2 times the height of Mount Everest

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

in line with the area average (~21 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: 35 months ago the same area had a stronger quake (M1.8). This can only be said after the fact — it was not predictable beforehand.

1.8
The mainshock
3 km South-West of Ragusa
35 months ago · 2 Oct, 18:33
Activity in the area right now (30 km radius)
0
last 24 hours
0
last 7 days
3
last 30 days
4 before5 after
this quake
Strongest of the sequence1.8

How often does it happen here?

about every ~24 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 180 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.

16937.3
Sicilia sud-orientale earthquake
11 January 1693 · 41 km from here
XICatastrophic: very few buildings remain standing; landslides and ground cracks.
15426.7
Sicilia sud-orientale earthquake
10 December 1542 · 37 km from here
XCompletely destructive: most buildings are destroyed.
11696.5
Sicilia sud-orientale earthquake
4 February 1169 · 37 km from here
XCompletely destructive: most buildings are destroyed.
16936.1
Sicilia sud-orientale earthquake
9 January 1693 · 43 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 15 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
2 km East of Licodia Eubea
15 km East · 17 km
36 months ago
21 Sept, 08:14
1.5
1 km West of Comiso
15 km South · 24 km
36 months ago
28 Aug, 07:15
1.7
5 km East of Acate
13 km South-West · 25 km
37 months ago
24 Aug, 15:04
1.8
3 km South-West of Ragusa
25 km South-East · 10 km
35 months ago
2 Oct, 18:33
1.0
4 km South-West of Ragusa
25 km South-East · 7 km
35 months ago
2 Oct, 20:26
1.5
3 km South-West of Ragusa
25 km South-East · 9 km
37 months ago
14 Aug, 00:16
1.8
3 km South-West of Ragusa
25 km South-East · 9 km
37 months ago
13 Aug, 23:28
1.0
6 km North-West of Modica
29 km South-East · 20 km
35 months ago
11 Oct, 21:00
1.5
6 km North-West of Modica
29 km South-East · 21 km
35 months ago
11 Oct, 21:10

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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