All earthquakes
1.3
very light
EARTHQUAKE DETAILS

20 km West of Pontechianale

121 months ago · 6 Sept, 02:33

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

20 km West of PontechianaleEarthquakes 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

9 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 ≈ 33 s

Animation sped up ~6× compared to reality.

  • Cuneo
    69 km from the epicentre
    first tremor in ~12 s
    main shaking in ~20 s
  • Moncalieri
    78 km from the epicentre
    first tremor in ~13 s
    main shaking in ~23 s
  • Torino
    85 km from the epicentre
    first tremor in ~14 s
    main shaking in ~24 s
  • Asti
    115 km from the epicentre
    first tremor in ~19 s
    main shaking in ~33 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: 120 months ago the same area had a stronger quake (M2.3). This can only be said after the fact — it was not predictable beforehand.

2.3
The mainshock
23 km West of Pontechianale
120 months ago · 4 Oct, 10:19
Activity in the area right now (30 km radius)
0
last 24 hours
1
last 7 days
10
last 30 days
4 before4 after
this quake
Strongest of the sequence2.3

How often does it happen here?

about every ~18 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 238 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 · 40 km from here
VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
19595.4
Ubaye earthquake
5 April 1959 · 21 km from here
VII-VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
18085.3
Val Pellice earthquake
16 April 1808 · 45 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 · 15 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 lies about 3 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

1.1
13 km South of Claviere
12 km North · 11 km
121 months ago
6 Sept, 09:59
0.6
4 km East of Bellino
24 km South-East · 10 km
122 months ago
28 Aug, 21:13
0.8
2 km East of Casteldelfino
29 km East · 10 km
122 months ago
27 Aug, 00:21
1.5
14 km North-West of Bellino
8 km South-East · 8 km
121 months ago
17 Sept, 01:13
1.2
9 km North-West of Bellino
13 km South-East · 9 km
121 months ago
18 Sept, 01:24
1.1
2 km North-East of Bellino
22 km South-East · 11 km
122 months ago
12 Aug, 02:07
2.3
120 months ago
4 Oct, 10:19
1.0
18 km West of Acceglio
23 km South · 10 km
122 months ago
8 Aug, 04:29

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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