All earthquakes
1.2
very light
EARTHQUAKE DETAILS

2 km West of Saint-Rhémy-en-Bosses

44 months ago · 4 Jan, 17:24

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 47% of Italian events in the past year

Where

2 km West of Saint-Rhémy-en-BossesEarthquakes 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

9 events
Magnitude:lightweakmoderatestrong

The energy released

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

1.0kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×501 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 ≈ 37 s

Animation sped up ~7× compared to reality.

  • Torino
    92 km from the epicentre
    first tremor in ~16 s
    main shaking in ~27 s
  • Moncalieri
    105 km from the epicentre
    first tremor in ~18 s
    main shaking in ~30 s
  • Novara
    123 km from the epicentre
    first tremor in ~21 s
    main shaking in ~35 s
  • Gallarate
    130 km from the epicentre
    first tremor in ~22 s
    main shaking in ~37 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
1.1 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 (M1.8, 44 months ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

1.8
The mainshock
5 km West of Arvier
44 months ago · 3 Jan, 00:13
Activity in the area right now (30 km radius)
0
last 24 hours
0
last 7 days
0
last 30 days
6 before2 after
this quake
Strongest of the sequence1.8

How often does it happen here?

about every ~41 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 103 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 · 36 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 · 49 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 · 24 km from here
VII-VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
19054.9
Massif du Mont-Blanc earthquake
13 August 1905 · 20 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 17 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

1.8
5 km West of Arvier
20 km South-West · 1 km
44 months ago
3 Jan, 00:13
1.6
5 km West of Arvier
20 km South-West · 9 km
45 months ago
30 Dec, 08:54
1.3
4 km East of La Thuile
17 km South-West · 11 km
44 months ago
15 Jan, 09:17
1.0
3 km North-East of Ollomont
18 km North-East · 14 km
44 months ago
23 Jan, 08:49
0.8
45 months ago
15 Dec, 23:22
1.5
9 km West of Saint-Rhémy-en-Bosses
8 km North-West · 11 km
45 months ago
15 Dec, 06:12
1.5
8 km East of Courmayeur
8 km West · 11 km
45 months ago
14 Dec, 19:04
1.6
45 months ago
10 Dec, 19:12

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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