All earthquakes
1.3
very light
EARTHQUAKE DETAILS

3 km North of Courmayeur

72 months ago · 4 Oct, 20:15

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 55% of Italian events in the past year

Where

3 km North of CourmayeurEarthquakes 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

56 events
Magnitude:lightweakmoderatestrong

The energy released

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

1.3kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×355 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 ≈ 41 s

Animation sped up ~8× compared to reality.

  • Torino
    103 km from the epicentre
    first tremor in ~17 s
    main shaking in ~30 s
  • Moncalieri
    115 km from the epicentre
    first tremor in ~19 s
    main shaking in ~33 s
  • Novara
    138 km from the epicentre
    first tremor in ~23 s
    main shaking in ~39 s
  • Asti
    144 km from the epicentre
    first tremor in ~24 s
    main shaking in ~41 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

10 km
shallow
1.1 times the height of Mount Everest

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?

Aftershock

It is an aftershock: it follows a stronger quake (M2.4, 72 months ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

2.4
The mainshock
2 km East of Morgex
72 months ago · 2 Oct, 11:52
Activity in the area right now (30 km radius)
0
last 24 hours
0
last 7 days
0
last 30 days
45 before10 after
this quake
Strongest of the sequence2.4

How often does it happen here?

about every ~43 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 99 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.

18175.4
Massif du Mont-Blanc earthquake
11 March 1817 · 23 km from here
VIIVery strong: hard to stand; chimneys and roof tiles fall, serious damage to weaker buildings.
18795.2
Chablais earthquake
30 December 1879 · 36 km from here
VIIVery strong: hard to stand; chimneys and roof tiles fall, serious damage to weaker buildings.
19055.1
Haute-Savoie, Vallorcine earthquake
29 April 1905 · 18 km from here
VII-VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
19054.9
Massif du Mont-Blanc earthquake
13 August 1905 · 13 km from here
VIIVery strong: hard to stand; chimneys and roof tiles fall, serious damage to weaker buildings.

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

The closest seismic structure

Chamonix

The epicentre lies about 3 km from Chamonix, 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
72 months ago
5 Oct, 09:03
2.4
2 km East of Morgex
14 km South-East · 10 km
72 months ago
2 Oct, 11:52
1.5
72 months ago
1 Oct, 10:29
2.3
72 months ago
1 Oct, 10:25
0.7
10 km North of Courmayeur
7 km North · 5 km
72 months ago
8 Oct, 22:01
1.1
72 months ago
28 Sept, 04:47
1.9
72 months ago
12 Oct, 18:04
1.0
72 months ago
13 Oct, 05:50
1.2
72 months ago
25 Sept, 20:23
1.3
5 km North-East of Courmayeur
2 km North-East · 10 km
72 months ago
25 Sept, 01:19

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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