All earthquakes
0.9
very light
EARTHQUAKE DETAILS

M0.9 earthquake · 3 km North of Boves (CN)

5 years ago · 22 Sept 2021, 17:20

A very light earthquake, probably not felt by people. At this depth the shaking is felt, but rarely causes damage.

Stronger than 23% of Italian events in the past year

Where

3 km North of BovesEarthquakes 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

24 events
Magnitude:lightweakmoderatestrong

The energy released

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

0.3kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×1,413 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 ≈ 21 s

Animation sped up ~4× compared to reality.

  • Cuneo
    10 km from the epicentre
    first tremor in ~2 s
    main shaking in ~4 s
  • Sanremo
    57 km from the epicentre
    first tremor in ~10 s
    main shaking in ~17 s
  • Savona
    72 km from the epicentre
    first tremor in ~12 s
    main shaking in ~21 s
  • Moncalieri
    73 km from the epicentre
    first tremor in ~12 s
    main shaking in ~21 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
medium depth
1.1 times the height of Mount Everest

At this depth the shaking is felt, but rarely causes damage.

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 (M2.1, 5 years ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

2.1
The mainshock
2 km South-West of Valgrana
5 years ago · 13 Sept 2021, 16:23
Activity in the area right now (30 km radius)
0
last 24 hours
4
last 7 days
9
last 30 days
13 before10 after
this quake
Strongest of the sequence2.1

How often does it happen here?

about every ~28 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 155 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 · 41 km from here
VIII-IXDestructive: many buildings partly or fully collapse.
16445.7
Alpes Niçoises earthquake
15 February 1644 · 47 km from here
VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
16185.6
Alpes Niçoises earthquake
18 January 1618 · 45 km from here
VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
19684.9
Liguria occidentale earthquake
18 April 1968 · 49 km from here

Source: Parametric Catalogue of Italian Earthquakes CPTI15 (INGV, CC BY 4.0).

The closest seismic structure

Southern Piemonte

The epicentre lies about 31 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
2 km East of Frabosa Soprana
23 km East · 11 km
5 years ago
24 Sept 2021, 14:58
1.1
3 km North-East of Demonte
24 km West · 10 km
5 years ago
16 Sept 2021, 21:16
1.4
1 km North-West of Pradleves
26 km West · 14 km
5 years ago
16 Sept 2021, 14:27
1.1
2 km North-East of Roccabruna
27 km North-West · 6 km
5 years ago
29 Sept 2021, 21:32
0.7
5 years ago
14 Sept 2021, 17:52
2.1
2 km South-West of Valgrana
18 km West · 10 km
5 years ago
13 Sept 2021, 16:23
1.5
2 km North-West of Rittana
18 km West · 10 km
5 years ago
13 Sept 2021, 14:12
1.1
3 km East of Demonte
22 km West · 11 km
5 years ago
4 Oct 2021, 01:57
0.7
3 km West of Valloriate
19 km West · 8 km
5 years ago
10 Sept 2021, 01:01
0.7
3 km West of Roburent
23 km East · 11 km
5 years ago
9 Sept 2021, 11:17

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).