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2.8
light
EARTHQUAKE DETAILS

11 km North-West of Acceglio

25 months ago · 20 Aug, 11:51

A light earthquake, rarely felt by people. At only a few km deep the shaking is felt more sharply at the surface.

Stronger than 97% of Italian events in the past year

Where

11 km North-West of AcceglioEarthquakes in the province of CuneoEarthquakes in Piemonte

How far away could it be felt?

An estimate of how far people may have felt this quake.

  • up to ~5 km · felt only by some, at rest

The coloured rings on the map below show these distances.

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

59 events
Magnitude:lightweakmoderatestrong

The energy released

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

239kgof TNT equivalent
1.0 lightning bolt
M3
A magnitude 3 earthquake releases ×2 its energy
M2this quakeM4

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.

  • Cuneo
    56 km from the epicentre
    first tremor in ~10 s
    main shaking in ~16 s
  • Moncalieri
    82 km from the epicentre
    first tremor in ~14 s
    main shaking in ~24 s
  • Torino
    91 km from the epicentre
    first tremor in ~15 s
    main shaking in ~26 s
  • Sanremo
    107 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

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 (~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?

Seismic swarm

It is part of a seismic swarm: many closely spaced quakes in the same area, with no dominant shock. A typical, well-known behaviour of some Italian areas.

Activity in the area right now (30 km radius)
1
last 24 hours
3
last 7 days
12
last 30 days
32 before26 after
this quake
Strongest of the sequence2.7

How often does it happen here?

about every ~56 days

Within 50 km of this epicentre, a magnitude ≥ 2.5 earthquake has occurred on average this often: 76 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 · 45 km from here
VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
19595.4
Ubaye earthquake
5 April 1959 · 8 km from here
VII-VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
18085.3
Val Pellice earthquake
16 April 1808 · 50 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 · 24 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 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

2.7
11 km West of Acceglio
5 km South-West · 10 km
25 months ago
20 Aug, 12:04
2.1
11 km North-West of Acceglio
1 km South-West · 8 km
25 months ago
20 Aug, 12:10
2.3
10 km North-West of Acceglio
1 km South-East · 10 km
25 months ago
20 Aug, 11:29
1.5
11 km West of Acceglio
3 km South-West · 19 km
25 months ago
20 Aug, 12:15
2.4
12 km West of Acceglio
2 km West · 15 km
25 months ago
20 Aug, 12:17
2.6
11 km North-West of Acceglio
1 km South-West · 8 km
25 months ago
20 Aug, 12:39
0.8
10 km West of Acceglio
2 km South · 9 km
25 months ago
20 Aug, 12:45
1.5
25 months ago
20 Aug, 10:17
1.0
10 km North-West of Acceglio
1 km South-East · 10 km
25 months ago
20 Aug, 10:05
2.3
25 months ago
20 Aug, 10:02

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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