All earthquakes
1.5
very light
EARTHQUAKE DETAILS

M1.5 earthquake · 3 km South-West of Stroppo (CN)

4 years ago · 3 Oct 2022, 01:39

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 69% of Italian events in the past year

Where

3 km South-West of StroppoEarthquakes in the province of CuneoEarthquakes in Piemonte

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

26 events
Magnitude:lightweakmoderatestrong

The energy released

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

2.7kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×178 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 ≈ 26 s

Animation sped up ~5× compared to reality.

  • Cuneo
    37 km from the epicentre
    first tremor in ~6 s
    main shaking in ~11 s
  • Moncalieri
    71 km from the epicentre
    first tremor in ~12 s
    main shaking in ~21 s
  • Torino
    82 km from the epicentre
    first tremor in ~14 s
    main shaking in ~24 s
  • Sanremo
    92 km from the epicentre
    first tremor in ~15 s
    main shaking in ~26 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
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 (~11 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 years ago the same area had a stronger quake (M2.2). This can only be said after the fact — it was not predictable beforehand.

2.2
The mainshock
2 km West of Cartignano
4 years ago · 11 Oct 2022, 05:40
Activity in the area right now (30 km radius)
0
last 24 hours
7
last 7 days
31
last 30 days
8 before17 after
this quake
Strongest of the sequence2.2

How often does it happen here?

about every ~15 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 291 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.

18085.6
Val Pellice earthquake
2 April 1808 · 39 km from here
VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
19595.4
Ubaye earthquake
5 April 1959 · 27 km from here
VII-VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
18085.3
Val Pellice earthquake
16 April 1808 · 42 km from here
VIIVery strong: hard to stand; chimneys and roof tiles fall, serious damage to weaker buildings.
19355.3
Embrunais earthquake
19 March 1935 · 42 km from here
VII-VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.

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

The closest seismic structure

Brianconnais

The epicentre lies about 9 km from Brianconnais, one of the seismic structures mapped by INGV geologists.

estimated maximum magnitude 7.2between 5 and 20 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

1.3
3 km East of Pradleves
19 km East · 10 km
4 years ago
2 Oct 2022, 22:44
1.6
3 km East of Sampeyre
13 km North-East · 14 km
4 years ago
4 Oct 2022, 14:39
1.0
3 km North-East of Sampeyre
15 km North-East · 11 km
4 years ago
7 Oct 2022, 07:38
1.4
14 km West of Argentera
28 km West · 12 km
4 years ago
10 Oct 2022, 10:06
1.0
11 km West of Argentera
25 km West · 10 km
4 years ago
25 Sept 2022, 08:53
2.2
2 km West of Cartignano
13 km East · 15 km
4 years ago
11 Oct 2022, 05:40
1.2
1 km West of Pradleves
15 km South-East · 11 km
4 years ago
21 Sept 2022, 06:20
1.0
1 km North of Pradleves
16 km East · 12 km
3 years ago
16 Oct 2022, 04:13
1.5
3 km West of Frassino
14 km North-East · 12 km
3 years ago
16 Oct 2022, 15:27
0.8
2 km South-East of Pontechianale
15 km North-West · 12 km
3 years ago
17 Oct 2022, 03:54

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).