All earthquakes
1.4
very light
EARTHQUAKE DETAILS

M1.4 earthquake outside Italy

11 years ago · 25 Apr 2015, 14:37

A very light earthquake, probably not felt by people. At only a few km deep the shaking is felt more sharply at the surface.

Where

Nearest Italian town: Bardonecchia (TO)Earthquakes in the province of TorinoEarthquakes in Piemonte

Epicentre abroad

The epicentre lies outside Italy's borders. The quake appears here because the INGV seismic network also records events close to Italy, which can be felt on Italian territory.

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

5 events
Magnitude:lightweakmoderatestrong

The energy released

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

1.9kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×251 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 ≈ 38 s

Animation sped up ~7× compared to reality.

  • Moncalieri
    93 km from the epicentre
    first tremor in ~16 s
    main shaking in ~27 s
  • Torino
    93 km from the epicentre
    first tremor in ~16 s
    main shaking in ~27 s
  • Cuneo
    105 km from the epicentre
    first tremor in ~18 s
    main shaking in ~30 s
  • Asti
    133 km from the epicentre
    first tremor in ~22 s
    main shaking in ~38 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 (~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?

Foreshock

In hindsight it was a foreshock: 11 years ago the same area had a stronger quake (M1.9). This can only be said after the fact — it was not predictable beforehand.

1.9
The mainshock
13 km West of Bardonecchia
11 years ago · 17 May 2015, 19:11
Activity in the area right now (30 km radius)
0
last 24 hours
0
last 7 days
5
last 30 days
2 before2 after
this quake
Strongest of the sequence1.9

How often does it happen here?

about every ~48 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 90 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.

19355.3
Embrunais earthquake
19 March 1935 · 41 km from here
VII-VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
18845.2
Alpi Cozie earthquake
27 November 1884 · 12 km from here
VIIVery strong: hard to stand; chimneys and roof tiles fall, serious damage to weaker buildings.
19045.1
Briançonnais earthquake
12 July 1904 · 15 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 · 46 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 6 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

1.3
3 km South of Claviere
22 km South-East · 10 km
11 years ago
26 Apr 2015, 01:29
0.7
3 km North-West of Oulx
21 km East · 4 km
11 years ago
11 Apr 2015, 08:54
1.9
13 km West of Bardonecchia
6 km East · 10 km
11 years ago
17 May 2015, 19:11
1.2
5 km North-East of Bardonecchia
22 km North-East · 4 km
11 years ago
27 Mar 2015, 13:01

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).