All earthquakes
1.3
very light
EARTHQUAKE DETAILS

M1.3 earthquake outside Italy

8 years ago · 28 Jun 2018, 18:32

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: Argentera (CN)Earthquakes in the province of CuneoEarthquakes 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

11 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 ≈ 31 s

Animation sped up ~6× compared to reality.

  • Cuneo
    58 km from the epicentre
    first tremor in ~10 s
    main shaking in ~17 s
  • Sanremo
    96 km from the epicentre
    first tremor in ~16 s
    main shaking in ~28 s
  • Moncalieri
    98 km from the epicentre
    first tremor in ~16 s
    main shaking in ~28 s
  • Torino
    108 km from the epicentre
    first tremor in ~18 s
    main shaking in ~31 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: 8 years ago the same area had a stronger quake (M3.2). This can only be said after the fact — it was not predictable beforehand.

3.2
The mainshock
2 km West of Stroppo
8 years ago · 17 Jul 2018, 20:13
Activity in the area right now (30 km radius)
0
last 24 hours
3
last 7 days
7
last 30 days
3 before7 after
this quake
Strongest of the sequence3.2

How often does it happen here?

about every ~15 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 283 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 · 19 km from here
VII-VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
19355.3
Embrunais earthquake
19 March 1935 · 37 km from here
VII-VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
19385.1
Queyras earthquake
18 July 1938 · 34 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 · 20 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 10 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

0.9
17 km West of Acceglio
15 km North-West · 9 km
8 years ago
25 Jun 2018, 11:16
1.6
20 km West of Argentera
11 km North-West · 17 km
8 years ago
6 Jul 2018, 04:05
1.3
Confine Italia-Francia (FRANCIA)
21 km South · 10 km
8 years ago
20 Jun 2018, 20:57
0.8
2 km North of Argentera
11 km East · 11 km
8 years ago
13 Jul 2018, 12:37
3.2
2 km West of Stroppo
28 km North-East · 10 km
8 years ago
17 Jul 2018, 20:13
1.1
21 km South-West of Argentera
12 km South-West · 10 km
8 years ago
18 Jul 2018, 19:21
1.3
6 km East of Sambuco
26 km East · 9 km
8 years ago
18 Jul 2018, 20:55
1.4
4 km South-West of Stroppo
27 km North-East · 10 km
8 years ago
22 Jul 2018, 06:50
2.0
11 km West of Bellino
23 km North · 9 km
8 years ago
30 May 2018, 22:53
1.4
15 km South-West of Pietraporzio
16 km South-East · 10 km
8 years ago
28 Jul 2018, 08:08

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).