All earthquakes
1.3
very light
EARTHQUAKE DETAILS

18 km North-East of Courmayeur

35 months ago · 24 Oct, 11:22

A very light earthquake, probably not felt by people. At this depth the shaking is felt, but rarely causes damage.

Stronger than 55% of Italian events in the past year

Where

18 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

18 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 ≈ 40 s

Animation sped up ~8× compared to reality.

  • Torino
    113 km from the epicentre
    first tremor in ~19 s
    main shaking in ~32 s
  • Moncalieri
    125 km from the epicentre
    first tremor in ~21 s
    main shaking in ~36 s
  • Novara
    139 km from the epicentre
    first tremor in ~23 s
    main shaking in ~40 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

14 km
medium depth
1.5 times the height of Mount Everest

At this depth the shaking is felt, but rarely causes damage.

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 (M1.7, 35 months ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

1.7
The mainshock
4 km North-West of Saint-Pierre
35 months ago · 15 Oct, 04:11
Activity in the area right now (30 km radius)
0
last 24 hours
0
last 7 days
1
last 30 days
15 before2 after
this quake
Strongest of the sequence1.7

How often does it happen here?

about every ~32 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 133 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 · 39 km from here
15245.8
Vallese, Ardon earthquake
April 1524 · 38 km from here
19465.5
Vallese, Sierre earthquake
30 May 1946 · 48 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.

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

The closest seismic structure

Chamonix

The epicentre sits above this source area: the deep structure where this area's earthquakes can originate.

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
6 km East of Courmayeur
16 km South · 11 km
35 months ago
24 Oct, 04:56
1.1
8 km East of Courmayeur
14 km South · 11 km
35 months ago
17 Oct, 14:41
1.7
4 km North-West of Saint-Pierre
27 km South-East · 5 km
35 months ago
15 Oct, 04:11
1.6
35 months ago
13 Oct, 19:34
1.1
35 months ago
12 Oct, 15:09
1.2
7 km East of Courmayeur
15 km South · 11 km
35 months ago
11 Oct, 20:17
1.2
7 km East of Courmayeur
16 km South · 11 km
35 months ago
11 Oct, 12:43
1.1
35 months ago
8 Oct, 03:46
1.0
7 km West of Saint-Rhémy-en-Bosses
16 km South-East · 10 km
35 months ago
7 Oct, 15:17
1.4
35 months ago
4 Oct, 20:34

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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