All earthquakes
0.9
very light
EARTHQUAKE DETAILS

17 km West of Acceglio

100 months ago · 25 Jun, 11:16

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 23% of Italian events in the past year

Where

17 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

14 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.

  • Cuneo
    63 km from the epicentre
    first tremor in ~11 s
    main shaking in ~18 s
  • Moncalieri
    93 km from the epicentre
    first tremor in ~16 s
    main shaking in ~27 s
  • Torino
    102 km from the epicentre
    first tremor in ~17 s
    main shaking in ~29 s
  • Sanremo
    108 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 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: 99 months ago the same area had a stronger quake (M3.2). This can only be said after the fact — it was not predictable beforehand.

3.2
The mainshock
2 km West of Stroppo
99 months ago · 17 Jul, 20:13
Activity in the area right now (30 km radius)
0
last 24 hours
3
last 7 days
9
last 30 days
4 before9 after
this quake
Strongest of the sequence3.2

How often does it happen here?

about every ~16 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 268 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.

19595.4
Ubaye earthquake
5 April 1959 · 4 km from here
VII-VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
19355.3
Embrunais earthquake
19 March 1935 · 23 km from here
VII-VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
19045.1
Briançonnais earthquake
12 July 1904 · 50 km from here
VIIVery strong: hard to stand; chimneys and roof tiles fall, serious damage to weaker buildings.
19385.1
Queyras earthquake
18 July 1938 · 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

Brianconnais

The epicentre lies about 4 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

1.4
19 km North-West of Bellino
22 km North · 7 km
100 months ago
24 Jun, 17:51
1.3
11 km West of Argentera
15 km South-East · 9 km
99 months ago
28 Jun, 18:32
1.2
19 km West of Pontechianale
24 km North · 9 km
99 months ago
6 Jul, 02:52
1.6
20 km West of Argentera
8 km South-West · 17 km
99 months ago
6 Jul, 04:05
0.8
2 km North of Argentera
18 km South-East · 11 km
99 months ago
13 Jul, 12:37
3.2
2 km West of Stroppo
28 km East · 10 km
99 months ago
17 Jul, 20:13
1.4
0 km South-East of Stroppo
30 km East · 10 km
99 months ago
17 Jul, 20:28
1.1
21 km South-West of Argentera
24 km South · 10 km
99 months ago
18 Jul, 19:21
2.0
99 months ago
20 Jul, 05:36
2.0
11 km West of Bellino
11 km North-East · 9 km
100 months ago
30 May, 22:53

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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