All earthquakes
1.9
very light
EARTHQUAKE DETAILS

10 km North-East of Courmayeur

3 months ago · 27 May, 10:19

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 85% of Italian events in the past year

Where

10 km North-East 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

25 events
Magnitude:lightweakmoderatestrong

The energy released

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

11kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×45 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 ≈ 41 s

Animation sped up ~8× compared to reality.

  • Torino
    108 km from the epicentre
    first tremor in ~18 s
    main shaking in ~31 s
  • Moncalieri
    119 km from the epicentre
    first tremor in ~20 s
    main shaking in ~34 s
  • Novara
    138 km from the epicentre
    first tremor in ~23 s
    main shaking in ~40 s
  • Varese
    142 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

9 km
shallow
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?

Mainshock

It is the strongest quake of its sequence: so far it has been followed by 10 aftershocks within 30 km. Aftershocks tend to fade in number and strength over time.

Activity in the area right now (30 km radius)
0
last 24 hours
0
last 7 days
1
last 30 days
14 before10 after
this quake
Strongest of the sequence1.8

How often does it happen here?

about every ~34 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 124 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.

15845.9
Vaud, Aigle earthquake
11 March 1584 · 46 km from here
15245.8
Vallese, Ardon earthquake
April 1524 · 45 km from here
18175.4
Massif du Mont-Blanc earthquake
11 March 1817 · 21 km from here
VIIVery strong: hard to stand; chimneys and roof tiles fall, serious damage to weaker buildings.
15845.4
Vaud, Aigle earthquake
14 March 1584 · 45 km from here

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

The closest seismic structure

Chamonix

The epicentre lies about 1 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

0.6
3 months ago
25 May, 10:00
1.5
3 months ago
23 May, 04:36
1.3
3 months ago
20 May, 01:04
0.7
3 months ago
18 May, 12:04
1.3
10 km North-East of Courmayeur
6 km South-East · 11 km
3 months ago
18 May, 10:37
1.6
3 months ago
14 May, 04:29
1.6
4 months ago
13 May, 02:11
1.7
8 km East of Courmayeur
8 km South-East · 10 km
3 months ago
11 Jun, 00:28
1.1
11 km North-East of Courmayeur
6 km South-East · 10 km
4 months ago
11 May, 14:21
1.2
4 months ago
8 May, 19:26

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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