All earthquakes
0.9
very light
EARTHQUAKE DETAILS

4 km North-East of Quart

4 months ago · 18 Apr, 22:57

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

Stronger than 23% of Italian events in the past year

Where

4 km North-East of QuartEarthquakes 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

13 events
Magnitude:lightweakmoderatestrong

The energy released

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

0.3kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×1,413 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 ≈ 31 s

Animation sped up ~6× compared to reality.

  • Torino
    82 km from the epicentre
    first tremor in ~14 s
    main shaking in ~24 s
  • Moncalieri
    95 km from the epicentre
    first tremor in ~16 s
    main shaking in ~27 s
  • Novara
    100 km from the epicentre
    first tremor in ~17 s
    main shaking in ~29 s
  • Gallarate
    106 km from the epicentre
    first tremor in ~18 s
    main shaking in ~31 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
medium depth
1.2 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?

Foreshock

In hindsight it was a foreshock: 4 months ago the same area had a stronger quake (M1.8). This can only be said after the fact — it was not predictable beforehand.

1.8
The mainshock
8 km North-West of Saint-Rhémy-en-Bosses
4 months ago · 2 May, 16:21
Activity in the area right now (30 km radius)
0
last 24 hours
0
last 7 days
0
last 30 days
2 before10 after
this quake
Strongest of the sequence1.8

How often does it happen here?

about every ~37 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 116 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.

19055.1
Haute-Savoie, Vallorcine earthquake
29 April 1905 · 40 km from here
VII-VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
18925.0
Valle d'Aosta earthquake
5 March 1892 · 38 km from here
VII-VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
19054.9
Massif du Mont-Blanc earthquake
13 August 1905 · 39 km from here
VIIVery strong: hard to stand; chimneys and roof tiles fall, serious damage to weaker buildings.
18514.9
Berna, Grone earthquake
24 August 1851 · 49 km from here

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

The closest seismic structure

Chamonix

The epicentre lies about 37 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

0.3
5 km North of Torgnon
12 km North-East · 6 km
4 months ago
26 Apr, 13:13
0.4
3 km North-West of Quart
3 km West · 10 km
4 months ago
26 Apr, 13:54
1.3
3 km North-West of Arvier
30 km West · 8 km
5 months ago
6 Apr, 03:43
1.8
4 months ago
2 May, 16:21
1.6
4 km South-West of Valtournenche
15 km North-East · 11 km
5 months ago
26 Mar, 22:41
1.2
3 km West of Nus
1 km East · 11 km
3 months ago
13 May, 07:20
1.6
3 months ago
14 May, 04:29
1.6
10 km North of Valtournenche
25 km North-East · 10 km
3 months ago
15 May, 06:33
0.4
3 km South-East of Oyace
2 km North-West · 9 km
3 months ago
17 May, 14:51
0.5
3 km North of Quart
2 km West · 5 km
3 months ago
17 May, 21:11

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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