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2.4
light
EARTHQUAKE DETAILS

M2.4 earthquake · 4 km South-West of Malborghetto Valbruna (UD)

11 years ago · 8 Feb 2015, 02:40

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

Stronger than 94% of Italian events in the past year

Where

4 km South-West of Malborghetto ValbrunaEarthquakes 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

7 events
Magnitude:lightweakmoderatestrong

The energy released

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

60kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×7.9 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 ≈ 36 s

Animation sped up ~7× compared to reality.

  • Udine
    48 km from the epicentre
    first tremor in ~8 s
    main shaking in ~14 s
  • Pordenone
    83 km from the epicentre
    first tremor in ~14 s
    main shaking in ~24 s
  • Trieste
    98 km from the epicentre
    first tremor in ~16 s
    main shaking in ~28 s
  • Treviso
    127 km from the epicentre
    first tremor in ~21 s
    main shaking in ~36 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?

Aftershock

It is an aftershock: it follows a stronger quake (M3.8, 11 years ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

3.8
The mainshock
4 km West of Resiutta
11 years ago · 30 Jan 2015, 01:45
Activity in the area right now (30 km radius)
0
last 24 hours
1
last 7 days
4
last 30 days
5 before1 after
this quake
Strongest of the sequence3.8

How often does it happen here?

about every ~20 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 210 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.

13486.6
Alpi Giulie earthquake
25 January 1348 · 15 km from here
IX-XCompletely destructive: most buildings are destroyed.
19766.5
Friuli earthquake
6 May 1976 · 34 km from here
IX-XCompletely destructive: most buildings are destroyed.
15116.3
Friuli-Slovenia earthquake
26 March 1511 · 33 km from here
IXDestructive: many buildings partly or fully collapse.
16906.2
Carinthia, Villach earthquake
4 December 1690 · 41 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

Tarvisio

The epicentre lies about 3 km from Tarvisio, one of the seismic structures mapped by INGV geologists.

estimated maximum magnitude 7.0between 1 and 14 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

1.5
1 km North-East of Amaro
24 km West · 10 km
11 years ago
30 Jan 2015, 03:33
1.4
3 km North-East of Amaro
22 km West · 10 km
11 years ago
30 Jan 2015, 02:27
1.2
3 km North of Amaro
23 km West · 9 km
11 years ago
30 Jan 2015, 02:08
1.6
3 km North-East of Amaro
23 km West · 9 km
11 years ago
30 Jan 2015, 01:51
3.8
4 km West of Resiutta
20 km South-West · 10 km
11 years ago
30 Jan 2015, 01:45
1.3
11 years ago
17 Feb 2015, 14:46

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).