All earthquakes
0.4
very light
EARTHQUAKE DETAILS

4 km East of La Magdeleine

109 months ago · 23 Sept, 04:32

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

4 km East of La MagdeleineEarthquakes 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

14 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 ≈ 26 s

Animation sped up ~5× compared to reality.

  • Torino
    79 km from the epicentre
    first tremor in ~13 s
    main shaking in ~23 s
  • Novara
    85 km from the epicentre
    first tremor in ~14 s
    main shaking in ~24 s
  • Varese
    89 km from the epicentre
    first tremor in ~15 s
    main shaking in ~25 s
  • Gallarate
    89 km from the epicentre
    first tremor in ~15 s
    main shaking in ~26 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: 109 months ago the same area had a stronger quake (M1.2). This can only be said after the fact — it was not predictable beforehand.

1.2
The mainshock
5 km West of Macugnaga
109 months ago · 28 Sept, 00:20
Activity in the area right now (30 km radius)
0
last 24 hours
0
last 7 days
0
last 30 days
6 before7 after
this quake
Strongest of the sequence1.2

How often does it happen here?

about every ~51 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 84 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.

18556.2
Vallese, Stalden-Visp earthquake
25 July 1855 · 49 km from here
18555.5
Vallese, Stalden-Visp earthquake
26 July 1855 · 50 km from here
18555.3
Vallese, Stalden-Visp earthquake
26 July 1855 · 48 km from here
18805.2
Vallese, Embd earthquake
4 July 1880 · 47 km from here

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

The closest seismic structure

Western Valais

The epicentre lies about 47 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

1.1
1 km West of Issime
19 km South-East · 10 km
109 months ago
24 Sept, 14:54
0.3
1 km West of Issime
19 km South-East · 10 km
109 months ago
27 Sept, 21:43
1.2
5 km West of Macugnaga
25 km North-East · 13 km
109 months ago
28 Sept, 00:20
0.8
2 km West of Issime
18 km South-East · 10 km
108 months ago
1 Oct, 13:46
0.7
3 km North of Issogne
15 km South · 9 km
109 months ago
6 Sept, 10:02
0.8
2 km North of Issogne
16 km South · 10 km
109 months ago
6 Sept, 09:57
0.9
2 km North-West of Issogne
16 km South · 10 km
108 months ago
10 Oct, 11:42
0.6
4 km East of Challand-Saint-Anselme
15 km South-East · 11 km
108 months ago
11 Oct, 12:32
0.7
0 km South-West of Donnas
26 km South · 17 km
109 months ago
3 Sept, 13:46
0.8
3 km West of Issime
17 km South-East · 9 km
108 months ago
12 Oct, 19:24

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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