All earthquakes
1.9
very light
EARTHQUAKE DETAILS

5 km North-East of Courmayeur

71 months ago · 15 Oct, 07:00

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

5 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

52 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 ≈ 40 s

Animation sped up ~8× compared to reality.

  • Torino
    101 km from the epicentre
    first tremor in ~17 s
    main shaking in ~29 s
  • Moncalieri
    113 km from the epicentre
    first tremor in ~19 s
    main shaking in ~32 s
  • Novara
    134 km from the epicentre
    first tremor in ~22 s
    main shaking in ~38 s
  • Varese
    141 km from the epicentre
    first tremor in ~24 s
    main shaking in ~40 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?

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
38 before13 after
this quake
Strongest of the sequence2.4

How often does it happen here?

about every ~42 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 101 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 · 26 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 · 39 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 6 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

1.2
71 months ago
15 Oct, 06:21
1.0
8 km North-East of Courmayeur
2 km North-East · 11 km
72 months ago
13 Oct, 05:50
1.9
9 km North-East of Courmayeur
4 km North-East · 11 km
72 months ago
12 Oct, 18:04
0.7
10 km North of Courmayeur
7 km North-West · 5 km
72 months ago
8 Oct, 22:01
1.7
71 months ago
22 Oct, 09:38
1.2
71 months ago
22 Oct, 11:18
1.1
8 km North-East of Courmayeur
3 km North-East · 11 km
72 months ago
5 Oct, 09:03
1.3
3 km North of Courmayeur
4 km West · 10 km
72 months ago
4 Oct, 20:15
1.4
71 months ago
26 Oct, 04:11
1.5
1 km West of Doues
22 km East · 7 km
71 months ago
26 Oct, 10:05

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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