All earthquakes
1.9
very light
EARTHQUAKE DETAILS

4 km South-West of Forni di Sotto

60 months ago · 7 Sept, 19:29

A very light earthquake, probably not felt by people. At only a few km deep the shaking is felt more sharply at the surface.

Stronger than 85% of Italian events in the past year

Where

4 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

30 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 ≈ 28 s

Animation sped up ~5× compared to reality.

  • Pordenone
    48 km from the epicentre
    first tremor in ~8 s
    main shaking in ~14 s
  • Udine
    60 km from the epicentre
    first tremor in ~10 s
    main shaking in ~17 s
  • Treviso
    83 km from the epicentre
    first tremor in ~14 s
    main shaking in ~24 s
  • Bolzano
    96 km from the epicentre
    first tremor in ~16 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

6 km
shallow

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?

Mainshock

It is the strongest quake of its sequence: so far it has been followed by 21 aftershocks within 30 km. Aftershocks tend to fade in number and strength over time.

Activity in the area right now (30 km radius)
0
last 24 hours
2
last 7 days
7
last 30 days
8 before21 after
this quake
Strongest of the sequence1.9

How often does it happen here?

about every ~19 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 229 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 · 41 km from here
IX-XCompletely destructive: most buildings are destroyed.
15116.3
Friuli-Slovenia earthquake
26 March 1511 · 50 km from here
IXDestructive: many buildings partly or fully collapse.
18736.3
Alpago Cansiglio earthquake
29 June 1873 · 29 km from here
IX-XCompletely destructive: most buildings are destroyed.
19366.1
Alpago Cansiglio earthquake
18 October 1936 · 36 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 11 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

0.5
60 months ago
9 Sept, 12:23
1.2
4 km South-East of Forni di Sopra
3 km North-West · 8 km
60 months ago
9 Sept, 18:24
1.1
4 km North of Tramonti di Sopra
11 km South-East · 10 km
61 months ago
4 Sept, 22:17
0.5
4 km South of Verzegnis
26 km East · 9 km
60 months ago
12 Sept, 02:50
0.4
61 months ago
31 Aug, 23:57
0.8
3 km North-West of Verzegnis
24 km East · 10 km
61 months ago
30 Aug, 13:25
1.0
2 km West of Fanna
23 km South-East · 15 km
60 months ago
20 Sept, 16:34
1.7
2 km South of Fanna
26 km South-East · 11 km
60 months ago
20 Sept, 23:28
1.2
0 km West of Fanna
24 km South-East · 11 km
60 months ago
20 Sept, 23:31
1.7
1 km North-West of Fanna
23 km South-East · 11 km
60 months ago
21 Sept, 03:13

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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