All earthquakes
0.4
very light
EARTHQUAKE DETAILS

5 km West of Torgnon

72 months ago · 9 Oct, 20:55

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

5 km West of TorgnonEarthquakes in the province of AostaEarthquakes in Valle d'Aosta

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

8 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 ≈ 29 s

Animation sped up ~5× compared to reality.

  • Torino
    84 km from the epicentre
    first tremor in ~14 s
    main shaking in ~24 s
  • Novara
    97 km from the epicentre
    first tremor in ~16 s
    main shaking in ~28 s
  • Moncalieri
    98 km from the epicentre
    first tremor in ~16 s
    main shaking in ~28 s
  • Varese
    101 km from the epicentre
    first tremor in ~17 s
    main shaking in ~29 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 (~10 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: 71 months ago the same area had a stronger quake (M2.3). This can only be said after the fact — it was not predictable beforehand.

2.3
The mainshock
8 km North of Bionaz
71 months ago · 25 Oct, 14:37
Activity in the area right now (30 km radius)
0
last 24 hours
1
last 7 days
1
last 30 days
2 before5 after
this quake
Strongest of the sequence2.3

How often does it happen here?

about every ~33 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 129 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.

18555.3
Vallese, Stalden-Visp earthquake
26 July 1855 · 49 km from here
16855.3
Vallese, Mittelwallis earthquake
8 March 1685 · 50 km from here
18805.2
Vallese, Embd earthquake
4 July 1880 · 47 km from here
19055.1
Haute-Savoie, Vallorcine earthquake
29 April 1905 · 44 km from here
VII-VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.

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

The closest seismic structure

Western Valais

The epicentre lies about 37 km from Western Valais, one of the seismic structures mapped by INGV geologists.

estimated maximum magnitude 7.0between 3 and 15 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

1.2
8 km North of Bionaz
16 km North · 10 km
71 months ago
17 Oct, 02:51
2.3
8 km North of Bionaz
16 km North · 11 km
71 months ago
25 Oct, 14:37
0.8
8 km North of Bionaz
17 km North · 10 km
71 months ago
25 Oct, 15:44
1.5
1 km West of Doues
19 km West · 7 km
71 months ago
26 Oct, 10:05
0.5
21 km North of Bionaz
29 km North · 9 km
72 months ago
20 Sept, 17:06
1.1
6 km North of Bionaz
15 km North · 8 km
72 months ago
16 Sept, 20:42
1.4
20 km North of Valtournenche
29 km North-East · 8 km
71 months ago
4 Nov, 03:52

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).

We use cookies to analyse site traffic and improve your experience.

Privacy PolicyCookie Policy