All earthquakes
1.4
very light
EARTHQUAKE DETAILS

4 km West of Acceglio

138 months ago · 20 Apr, 05:26

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 63% of Italian events in the past year

Where

4 km West of AcceglioEarthquakes 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

61 events
Magnitude:lightweakmoderatestrong

The energy released

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

1.9kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×251 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 ≈ 29 s

Animation sped up ~5× compared to reality.

  • Cuneo
    51 km from the epicentre
    first tremor in ~9 s
    main shaking in ~15 s
  • Moncalieri
    82 km from the epicentre
    first tremor in ~14 s
    main shaking in ~24 s
  • Torino
    92 km from the epicentre
    first tremor in ~15 s
    main shaking in ~26 s
  • Sanremo
    101 km from the epicentre
    first tremor in ~17 s
    main shaking in ~29 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?

Aftershock

It is an aftershock: it follows a stronger quake (M3.2, 138 months ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

3.2
The mainshock
23 km West of Acceglio
138 months ago · 11 Apr, 07:33
Activity in the area right now (30 km radius)
0
last 24 hours
3
last 7 days
14
last 30 days
47 before28 after
this quake
Strongest of the sequence3.2

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: 281 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 · 46 km from here
VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
19595.4
Ubaye earthquake
5 April 1959 · 12 km from here
VII-VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
19355.3
Embrunais earthquake
19 March 1935 · 30 km from here
VII-VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
18085.1
Val Pellice earthquake
18 April 1808 · 48 km from here
VI-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

Brianconnais

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

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
4 km West of Acceglio
0 km East · 10 km
138 months ago
20 Apr, 05:24
1.5
6 km West of Acceglio
2 km West · 9 km
138 months ago
20 Apr, 07:25
1.4
5 km West of Acceglio
2 km South-West · 9 km
138 months ago
19 Apr, 22:29
1.1
4 km South-East of Sampeyre
26 km East · 8 km
138 months ago
20 Apr, 13:25
1.1
4 km North-West of Acceglio
2 km North-East · 11 km
138 months ago
19 Apr, 21:02
1.5
6 km North-West of Acceglio
2 km North · 8 km
138 months ago
20 Apr, 18:59
1.8
20 km West of Acceglio
16 km West · 9 km
138 months ago
19 Apr, 13:00
1.1
22 km West of Acceglio
18 km West · 10 km
138 months ago
19 Apr, 12:17
1.9
23 km West of Acceglio
19 km West · 11 km
138 months ago
19 Apr, 12:09
1.9
6 km West of Acceglio
2 km West · 10 km
138 months ago
19 Apr, 10:48

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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