All earthquakes
0.9
very light
EARTHQUAKE DETAILS

4 km West of Forni di Sotto

115 months ago · 20 Mar, 11:02

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 23% of Italian events in the past year

Where

4 km 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.

0.3kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×1,413 its energy
M0this quakeM2

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 ≈ 27 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
    61 km from the epicentre
    first tremor in ~10 s
    main shaking in ~17 s
  • Treviso
    84 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 ~27 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

5 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?

Aftershock

It is an aftershock: it follows a stronger quake (M2.0, 115 months ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

2.0
The mainshock
1 km North-West of Chies d'Alpago
115 months ago · 11 Mar, 01:47
Activity in the area right now (30 km radius)
0
last 24 hours
2
last 7 days
7
last 30 days
9 before4 after
this quake
Strongest of the sequence2.0

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: 226 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 · 42 km from here
IX-XCompletely destructive: most buildings are destroyed.
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.
19286.0
Carnia earthquake
27 March 1928 · 29 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 12 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

0.8
3 km South-East of Preone
23 km East · 11 km
115 months ago
18 Mar, 18:02
0.8
3 km West of Preone
19 km East · 10 km
115 months ago
17 Mar, 18:54
1.8
1 km North of Preone
21 km East · 6 km
115 months ago
24 Mar, 00:06
0.7
3 km North of Alpago
30 km South-West · 15 km
115 months ago
24 Mar, 07:54
0.8
3 km South-West of Verzegnis
25 km East · 11 km
115 months ago
16 Mar, 04:30
1.5
1 km South-East of Claut
11 km South-West · 9 km
115 months ago
14 Mar, 03:11
0.9
1 km North of Ampezzo
11 km East · 7 km
115 months ago
11 Mar, 13:46
2.0
1 km North-West of Chies d'Alpago
25 km South-West · 5 km
115 months ago
11 Mar, 01:47
1.7
5 km East of Cimolais
7 km West · 9 km
115 months ago
7 Mar, 01:52
1.3
8 km South of Forni di Sotto
7 km South-East · 10 km
114 months ago
10 Apr, 16:57

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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