All earthquakes
1.0
very light
EARTHQUAKE DETAILS

21 km South-West of Claviere

106 months ago · 19 Dec, 12:49

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 30% of Italian events in the past year

Where

21 km South-West of ClaviereEarthquakes in the province of TorinoEarthquakes 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.

0.5kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×1,000 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 ≈ 36 s

Animation sped up ~7× compared to reality.

  • Cuneo
    81 km from the epicentre
    first tremor in ~14 s
    main shaking in ~23 s
  • Moncalieri
    87 km from the epicentre
    first tremor in ~15 s
    main shaking in ~25 s
  • Torino
    92 km from the epicentre
    first tremor in ~15 s
    main shaking in ~26 s
  • Asti
    125 km from the epicentre
    first tremor in ~21 s
    main shaking in ~36 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
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?

Aftershock

It is an aftershock: it follows a stronger quake (M2.9, 106 months ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

2.9
The mainshock
21 km South-West of Claviere
106 months ago · 19 Dec, 10:10
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 sequence2.9

How often does it happen here?

about every ~22 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 197 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 · 48 km from here
VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
19595.4
Ubaye earthquake
5 April 1959 · 28 km from here
VII-VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
19355.3
Embrunais earthquake
19 March 1935 · 12 km from here
VII-VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
18845.2
Alpi Cozie earthquake
27 November 1884 · 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 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

2.1
106 months ago
19 Dec, 10:45
2.9
106 months ago
19 Dec, 10:10
1.7
106 months ago
24 Dec, 04:14
2.1
16 km West of Bellino
26 km South-East · 11 km
106 months ago
12 Dec, 12:00
0.6
8 km West of Pontechianale
24 km East · 8 km
106 months ago
7 Dec, 01:39
1.4
4 km West of Pontechianale
29 km East · 10 km
105 months ago
11 Jan, 14:23
1.7
105 months ago
14 Jan, 22:55
1.1
22 km South-West of Claviere
1 km South-East · 9 km
105 months ago
14 Jan, 23:02

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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