All earthquakes
1.3
very light
EARTHQUAKE DETAILS

3 km South-East of Pradleves

110 months ago · 21 Aug, 06:31

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 55% of Italian events in the past year

Where

3 km South-East of PradlevesEarthquakes 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

29 events
Magnitude:lightweakmoderatestrong

The energy released

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

1.3kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×355 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 ≈ 24 s

Animation sped up ~5× compared to reality.

  • Cuneo
    21 km from the epicentre
    first tremor in ~4 s
    main shaking in ~7 s
  • Moncalieri
    72 km from the epicentre
    first tremor in ~12 s
    main shaking in ~21 s
  • Sanremo
    74 km from the epicentre
    first tremor in ~12 s
    main shaking in ~21 s
  • Torino
    85 km from the epicentre
    first tremor in ~14 s
    main shaking in ~24 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

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: 109 months ago the same area had a stronger quake (M2.4). This can only be said after the fact — it was not predictable beforehand.

2.4
The mainshock
2 km North of Sampeyre
109 months ago · 5 Sept, 06:34
Activity in the area right now (30 km radius)
0
last 24 hours
1
last 7 days
8
last 30 days
8 before20 after
this quake
Strongest of the sequence2.4

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: 266 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.

15645.8
Lantosque earthquake
20 July 1564 · 42 km from here
VIII-IXDestructive: many buildings partly or fully collapse.
16445.7
Alpes Niçoises earthquake
15 February 1644 · 47 km from here
VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
18085.6
Val Pellice earthquake
2 April 1808 · 49 km from here
VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
16185.6
Alpes Niçoises earthquake
18 January 1618 · 49 km from here
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 25 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

1.0
4 km East of Pradleves
3 km North-East · 10 km
110 months ago
19 Aug, 19:31
2.1
4 km North-West of Pradleves
6 km North-West · 8 km
110 months ago
24 Aug, 07:55
0.7
2 km West of Bernezzo
10 km East · 10 km
110 months ago
24 Aug, 11:08
1.2
110 months ago
17 Aug, 19:30
0.8
1 km East of Roccabruna
11 km North-East · 6 km
110 months ago
25 Aug, 06:46
1.0
3 km South-West of Melle
15 km North · 14 km
110 months ago
25 Aug, 10:28
1.2
2 km North-East of Frassino
21 km North · 7 km
110 months ago
25 Aug, 11:49
0.8
3 km North-West of Argentera
28 km West · 14 km
110 months ago
16 Aug, 03:51
1.1
109 months ago
30 Aug, 06:36
1.2
2 km East of Roccabruna
12 km North-East · 5 km
109 months ago
30 Aug, 12:53

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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