All earthquakes
1.1
very light
EARTHQUAKE DETAILS

Confine Italia-Francia (FRANCIA)

24 months ago · 26 Aug, 17:01

A very light earthquake, probably not felt by people. At this depth the shaking is felt, but rarely causes damage.

Stronger than 39% of Italian events in the past year

Where

Confine Italia-Francia (FRANCIA)Earthquakes in the province of CuneoEarthquakes in Piemonte

Epicentre at sea

The epicentre is at sea: for the same magnitude, the shaking is felt less on land, because the energy fades along the way before reaching the coast.

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

46 events
Magnitude:lightweakmoderatestrong

The energy released

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

0.7kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×708 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 ≈ 35 s

Animation sped up ~6× compared to reality.

  • Cuneo
    80 km from the epicentre
    first tremor in ~13 s
    main shaking in ~23 s
  • Moncalieri
    107 km from the epicentre
    first tremor in ~18 s
    main shaking in ~31 s
  • Torino
    115 km from the epicentre
    first tremor in ~19 s
    main shaking in ~33 s
  • Sanremo
    121 km from the epicentre
    first tremor in ~20 s
    main shaking in ~35 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
medium depth
1.1 times the height of Mount Everest

At this depth the shaking is felt, but rarely causes damage.

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 (M2.8, 25 months ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

2.8
The mainshock
11 km North-West of Acceglio
25 months ago · 20 Aug, 11:51
Activity in the area right now (30 km radius)
1
last 24 hours
2
last 7 days
5
last 30 days
35 before10 after
this quake
Strongest of the sequence2.8

How often does it happen here?

about every ~24 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 174 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 · 18 km from here
VII-VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
19355.3
Embrunais earthquake
19 March 1935 · 21 km from here
VII-VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
19385.1
Queyras earthquake
18 July 1938 · 16 km from here
VIIVery strong: hard to stand; chimneys and roof tiles fall, serious damage to weaker buildings.
20144.9
Ubaye earthquake
7 April 2014 · 14 km from here
VIStrong: felt by everyone, many get scared; objects fall, first light damage to buildings.

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

The closest seismic structure

Brianconnais

The epicentre lies about 18 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

1.5
10 km West of Bellino
27 km East · 8 km
24 months ago
26 Aug, 04:18
0.9
10 km North-West of Acceglio
25 km East · 10 km
24 months ago
24 Aug, 08:38
2.0
6 km West of Acceglio
28 km East · 9 km
24 months ago
29 Aug, 11:20
1.2
9 km West of Acceglio
27 km East · 10 km
24 months ago
29 Aug, 15:51
1.6
11 km West of Argentera
24 km East · 6 km
24 months ago
29 Aug, 19:00
2.4
8 km North-West of Acceglio
27 km East · 10 km
24 months ago
29 Aug, 19:25
0.8
10 km West of Acceglio
26 km East · 9 km
25 months ago
20 Aug, 12:45
2.6
25 months ago
20 Aug, 12:39
2.4
12 km West of Acceglio
24 km East · 15 km
25 months ago
20 Aug, 12:17
1.5
11 km West of Acceglio
24 km East · 19 km
25 months ago
20 Aug, 12:15

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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