All earthquakes
1.6
very light
EARTHQUAKE DETAILS

3 km South-West of Rosolini

37 months ago · 28 Aug, 21:56

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

3 km South-West of RosoliniEarthquakes in the province of SiracusaEarthquakes 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

11 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 ≈ 13 s

Animation sped up ~2× compared to reality.

  • Modica
    7 km from the epicentre
    first tremor in ~4 s
    main shaking in ~7 s
  • Ragusa
    20 km from the epicentre
    first tremor in ~5 s
    main shaking in ~9 s
  • Vittoria
    36 km from the epicentre
    first tremor in ~7 s
    main shaking in ~12 s
  • Siracusa
    37 km from the epicentre
    first tremor in ~7 s
    main shaking in ~13 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

25 km
medium depth
2.8 times the height of Mount Everest

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

deeper than the area average (~19 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: 36 months ago the same area had a stronger quake (M2.0). This can only be said after the fact — it was not predictable beforehand.

2.0
The mainshock
10 km West of Pachino
36 months ago · 18 Sept, 03:10
Activity in the area right now (30 km radius)
0
last 24 hours
0
last 7 days
4
last 30 days
4 before6 after
this quake
Strongest of the sequence2.0

How often does it happen here?

about every ~23 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 186 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 · 34 km from here
XICatastrophic: very few buildings remain standing; landslides and ground cracks.
15426.7
Sicilia sud-orientale earthquake
10 December 1542 · 41 km from here
XCompletely destructive: most buildings are destroyed.
11696.5
Sicilia sud-orientale earthquake
4 February 1169 · 41 km from here
XCompletely destructive: most buildings are destroyed.
16936.1
Sicilia sud-orientale earthquake
9 January 1693 · 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

Scicli-Giarratana

The epicentre lies about 11 km from Scicli-Giarratana, one of the seismic structures mapped by INGV geologists.

estimated maximum magnitude 7.0between 1 and 23 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

1.5
1 km West of Comiso
29 km North-West · 24 km
37 months ago
28 Aug, 07:15
1.5
5 km North of Noto
13 km East · 8 km
36 months ago
9 Sept, 04:26
1.9
9 km South-East of Avola
29 km East · 29 km
36 months ago
9 Sept, 12:40
1.3
5 km South-West of Modica
8 km West · 14 km
37 months ago
17 Aug, 04:17
1.5
3 km South-West of Ragusa
22 km West · 9 km
37 months ago
14 Aug, 00:16
1.8
3 km South-West of Ragusa
21 km West · 9 km
37 months ago
13 Aug, 23:28
1.4
4 km West of Scicli
23 km South-West · 29 km
36 months ago
15 Sept, 20:10
1.5
8 km South-East of Ispica
23 km South-East · 11 km
36 months ago
18 Sept, 03:09
2.0
10 km West of Pachino
19 km South-East · 10 km
36 months ago
18 Sept, 03:10
1.6
1 km West of Noto
13 km East · 21 km
36 months ago
18 Sept, 20:07

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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