All earthquakes
0.5
very light
EARTHQUAKE DETAILS

M0.5 earthquake · 2 km North-West of Roaschia (CN)

9 years ago · 24 May 2017, 09:01

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 3% of Italian events in the past year

Where

2 km North-West of RoaschiaEarthquakes 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

23 events
Magnitude:lightweakmoderatestrong

The energy released

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

0.1kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×5,623 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 ≈ 23 s

Animation sped up ~4× compared to reality.

  • Cuneo
    18 km from the epicentre
    first tremor in ~3 s
    main shaking in ~6 s
  • Sanremo
    54 km from the epicentre
    first tremor in ~9 s
    main shaking in ~16 s
  • Savona
    81 km from the epicentre
    first tremor in ~14 s
    main shaking in ~23 s
  • Moncalieri
    81 km from the epicentre
    first tremor in ~14 s
    main shaking in ~23 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

8 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?

Aftershock

It is an aftershock: it follows a stronger quake (M2.0, 9 years ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

2.0
The mainshock
2 km South-East of Demonte
9 years ago · 22 May 2017, 17:57
Activity in the area right now (30 km radius)
0
last 24 hours
6
last 7 days
12
last 30 days
11 before11 after
this quake
Strongest of the sequence2.0

How often does it happen here?

about every ~27 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 158 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 · 30 km from here
VIII-IXDestructive: many buildings partly or fully collapse.
16445.7
Alpes Niçoises earthquake
15 February 1644 · 36 km from here
VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
16185.6
Alpes Niçoises earthquake
18 January 1618 · 35 km from here
VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
19194.9
Alpi Marittime earthquake
28 November 1919 · 27 km from here
V-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

Southern Piemonte

The epicentre lies about 39 km from Southern Piemonte, one of the seismic structures mapped by INGV geologists.

estimated maximum magnitude 6.3between 2 and 8 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
3 km North of Monterosso Grana
19 km North-West · 13 km
9 years ago
24 May 2017, 10:00
2.0
2 km South-East of Demonte
16 km West · 10 km
9 years ago
22 May 2017, 17:57
1.1
4 km North-East of Caraglio
20 km North · 10 km
9 years ago
19 May 2017, 19:22
1.4
9 km South-West of Valdieri
19 km West · 12 km
9 years ago
18 May 2017, 13:54
1.2
2 km West of Roccavione
3 km North · 11 km
9 years ago
16 May 2017, 03:33
1.1
4 km South of Monterosso Grana
15 km North-West · 11 km
9 years ago
15 May 2017, 15:13
1.2
2 km South-East of Monterosso Grana
15 km North-West · 14 km
9 years ago
14 May 2017, 04:24
1.2
2 km South-East of Monterosso Grana
15 km North-West · 11 km
9 years ago
3 Jun 2017, 20:56
1.5
3 km East of Celle di Macra
29 km North-West · 11 km
9 years ago
9 May 2017, 08:35
1.0
2 km East of Roccabruna
28 km North-West · 4 km
9 years ago
8 May 2017, 17:18

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).