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3.0
weak
EARTHQUAKE DETAILS

2 km South-East of Sant'Agata di Militello

7 months ago · 20 Jan, 22:45

A weak earthquake, felt by some of the population. At only a few km deep the shaking is felt more sharply at the surface.

Stronger than 98% of Italian events in the past year

Where

2 km South-East of Sant'Agata di MilitelloEarthquakes in the province of MessinaEarthquakes in Sicilia

How far away could it be felt?

An estimate of how far people may have felt this quake.

  • up to ~10 km · felt only by some, at rest
    ≈ 37,000 people live in this area

The coloured rings on the map below show these distances.

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.

477kgof TNT equivalent
2.0 lightning bolts
M3
About the same energy as a magnitude 3 earthquake
M2this quakeM4

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
    62 km from the epicentre
    first tremor in ~11 s
    main shaking in ~18 s
  • Catania
    70 km from the epicentre
    first tremor in ~12 s
    main shaking in ~20 s
  • Messina
    78 km from the epicentre
    first tremor in ~13 s
    main shaking in ~22 s
  • Caltanissetta
    84 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

9 km
shallow

At only a few km deep the shaking is felt more sharply at the surface.

shallower than the area average (~14 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 (M4.1, 7 months ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

4.1
The mainshock
2 km East of Sant'Agata di Militello
7 months ago · 18 Jan, 14:54
Activity in the area right now (30 km radius)
0
last 24 hours
5
last 7 days
18
last 30 days
77 before58 after
this quake
Strongest of the sequence4.1

How often does it happen here?

about every ~23 days

Within 50 km of this epicentre, a magnitude ≥ 3 earthquake has occurred on average this often: 188 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.

17866.1
Golfo di Patti earthquake
10 March 1786 · 33 km from here
IXDestructive: many buildings partly or fully collapse.
18235.8
Sicilia settentrionale earthquake
5 March 1823 · 33 km from here
VIII-IXDestructive: many buildings partly or fully collapse.
16135.6
Monti Nebrodi earthquake
25 August 1613 · 16 km from here
IXDestructive: many buildings partly or fully collapse.
17395.4
Monti Nebrodi earthquake
10 May 1739 · 11 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

Patti-Giardini

The epicentre lies about 39 km from Patti-Giardini, one of the seismic structures mapped by INGV geologists.

estimated maximum magnitude 7.1between 3 and 20 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

2.6
7 months ago
20 Jan, 23:16
2.1
7 months ago
20 Jan, 21:13
3.6
7 months ago
21 Jan, 00:28
2.6
7 months ago
21 Jan, 00:50
2.0
7 months ago
21 Jan, 01:21
1.2
7 months ago
21 Jan, 04:22
2.7
7 months ago
21 Jan, 04:28
2.5
3 km East of Acquedolci
5 km North-West · 11 km
7 months ago
20 Jan, 15:02
1.7
2 km East of Acquedolci
6 km West · 14 km
7 months ago
21 Jan, 06:50
1.8
7 months ago
21 Jan, 09:11

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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