All earthquakes
0.4
very light
EARTHQUAKE DETAILS

2 km North-West of Preone

65 months ago · 27 Apr, 01:08

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 1% of Italian events in the past year

Where

2 km North-West of PreoneEarthquakes 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

10 events
Magnitude:lightweakmoderatestrong

The energy released

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

0.1kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×7,943 its energy
M-1this quakeM1

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 ≈ 31 s

Animation sped up ~6× compared to reality.

  • Udine
    46 km from the epicentre
    first tremor in ~8 s
    main shaking in ~13 s
  • Pordenone
    51 km from the epicentre
    first tremor in ~9 s
    main shaking in ~15 s
  • Treviso
    93 km from the epicentre
    first tremor in ~16 s
    main shaking in ~27 s
  • Trieste
    107 km from the epicentre
    first tremor in ~18 s
    main shaking in ~31 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

7 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?

Foreshock

In hindsight it was a foreshock: 65 months ago the same area had a stronger quake (M1.4). This can only be said after the fact — it was not predictable beforehand.

1.4
The mainshock
2 km West of Gemona del Friuli
65 months ago · 4 May, 01:29
Activity in the area right now (30 km radius)
1
last 24 hours
4
last 7 days
13
last 30 days
5 before4 after
this quake
Strongest of the sequence1.4

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: 240 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 · 24 km from here
IX-XCompletely destructive: most buildings are destroyed.
15116.3
Friuli-Slovenia earthquake
26 March 1511 · 32 km from here
IXDestructive: many buildings partly or fully collapse.
18736.3
Alpago Cansiglio earthquake
29 June 1873 · 44 km from here
IX-XCompletely destructive: most buildings are destroyed.
19366.1
Alpago Cansiglio earthquake
18 October 1936 · 49 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 6 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

0.7
3 km West of Enemonzo
5 km North-West · 5 km
65 months ago
1 May, 17:32
1.4
65 months ago
4 May, 01:29
0.7
4 km North of Tramonti di Sopra
12 km South-West · 9 km
65 months ago
4 May, 21:30
0.6
2 km East of Arta Terme
20 km North-East · 10 km
65 months ago
16 Apr, 04:16
0.3
2 km South-West of Bordano
17 km East · 5 km
66 months ago
6 Apr, 00:06
0.8
1 km South-East of Preone
3 km South-East · 10 km
66 months ago
4 Apr, 16:38
0.6
6 km North-East of Paluzza
29 km North-East · 11 km
66 months ago
3 Apr, 02:17
1.1
3 km North-East of Preone
2 km East · 11 km
66 months ago
31 Mar, 15:48
1.0
2 km South-East of Bordano
20 km East · 6 km
64 months ago
24 May, 07:50

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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