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2.2
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EARTHQUAKE DETAILS

6 km South-West of Forni di Sotto

56 months ago · 6 Feb, 03:05

A light earthquake, rarely felt by people. At only a few km deep the shaking is felt more sharply at the surface.

Stronger than 92% of Italian events in the past year

Where

6 km South-West of Forni di SottoEarthquakes in the province of UdineEarthquakes in Friuli-Venezia Giulia

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

14 events
Magnitude:lightweakmoderatestrong

The energy released

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

30kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×16 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 ≈ 28 s

Animation sped up ~5× compared to reality.

  • Pordenone
    44 km from the epicentre
    first tremor in ~8 s
    main shaking in ~13 s
  • Udine
    57 km from the epicentre
    first tremor in ~10 s
    main shaking in ~17 s
  • Treviso
    81 km from the epicentre
    first tremor in ~14 s
    main shaking in ~23 s
  • Bolzano
    98 km from the epicentre
    first tremor in ~17 s
    main shaking in ~28 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
shallow
1.1 times the height of Mount Everest

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

in line with the area average (~9 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: 55 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
8 km South-West of Forni di Sotto
55 months ago · 24 Feb, 19:34
Activity in the area right now (30 km radius)
0
last 24 hours
1
last 7 days
7
last 30 days
4 before9 after
this quake
Strongest of the sequence2.5

How often does it happen here?

about every ~18 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 233 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.

19766.5
Friuli earthquake
6 May 1976 · 39 km from here
IX-XCompletely destructive: most buildings are destroyed.
15116.3
Friuli-Slovenia earthquake
26 March 1511 · 47 km from here
IXDestructive: many buildings partly or fully collapse.
18736.3
Alpago Cansiglio earthquake
29 June 1873 · 27 km from here
IX-XCompletely destructive: most buildings are destroyed.
19366.1
Alpago Cansiglio earthquake
18 October 1936 · 34 km from here
IXDestructive: many buildings partly or fully collapse.

Source: Parametric Catalogue of Italian Earthquakes CPTI15 (INGV, CC BY 4.0).

The closest seismic structure

Tramonti-Montemaggiore

The epicentre lies about 9 km from Tramonti-Montemaggiore, one of the seismic structures mapped by INGV geologists.

estimated maximum magnitude 6.2between 1 and 6 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

2.0
3 km East of Villa Santina
28 km East · 7 km
56 months ago
3 Feb, 15:51
0.9
5 km East of Villa Santina
29 km East · 8 km
55 months ago
11 Feb, 15:25
0.5
5 km East of Villa Santina
29 km East · 6 km
55 months ago
14 Feb, 22:22
1.1
1 km West of Raveo
21 km North-East · 9 km
55 months ago
15 Feb, 23:27
1.2
55 months ago
16 Feb, 08:41
1.2
3 km South of Prato Carnico
18 km North-East · 10 km
56 months ago
26 Jan, 11:55
1.6
55 months ago
18 Feb, 10:01
1.2
2 km East of Claut
9 km South-West · 10 km
56 months ago
22 Jan, 18:58
1.5
55 months ago
21 Feb, 15:18
2.5
55 months ago
24 Feb, 19:34

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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