All earthquakes
0.6
very light
EARTHQUAKE DETAILS

1 km South-East of Monterosso Grana

14 months ago · 16 Jul, 20:20

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 6% of Italian events in the past year

Where

1 km South-East of Monterosso GranaEarthquakes 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

25 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 ×3,981 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 ≈ 25 s

Animation sped up ~5× compared to reality.

  • Cuneo
    20 km from the epicentre
    first tremor in ~4 s
    main shaking in ~6 s
  • Sanremo
    70 km from the epicentre
    first tremor in ~12 s
    main shaking in ~20 s
  • Moncalieri
    74 km from the epicentre
    first tremor in ~12 s
    main shaking in ~21 s
  • Torino
    87 km from the epicentre
    first tremor in ~15 s
    main shaking in ~25 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
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?

Foreshock

In hindsight it was a foreshock: 13 months ago the same area had a stronger quake (M1.7). This can only be said after the fact — it was not predictable beforehand.

1.7
The mainshock
2 km South-East of Marmora
13 months ago · 21 Jul, 09:48
Activity in the area right now (30 km radius)
1
last 24 hours
2
last 7 days
9
last 30 days
11 before13 after
this quake
Strongest of the sequence1.7

How often does it happen here?

about every ~17 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 250 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 · 39 km from here
VIII-IXDestructive: many buildings partly or fully collapse.
16445.7
Alpes Niçoises earthquake
15 February 1644 · 44 km from here
VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
16185.6
Alpes Niçoises earthquake
18 January 1618 · 46 km from here
VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
19595.4
Ubaye earthquake
5 April 1959 · 46 km from here
VII-VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.

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

The closest seismic structure

Brianconnais

The epicentre lies about 29 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

1.2
1 km South of Cartignano
12 km North · 9 km
14 months ago
17 Jul, 11:25
0.5
4 km North-East of Demonte
3 km South-West · 13 km
14 months ago
15 Jul, 04:38
0.6
5 km North-East of Valdieri
11 km South · 11 km
14 months ago
19 Jul, 01:37
1.2
2 km North-East of Pradleves
7 km North-West · 10 km
13 months ago
20 Jul, 06:59
1.2
2 km South-West of Marmora
17 km West · 8 km
13 months ago
21 Jul, 00:29
1.7
2 km South-East of Marmora
15 km West · 8 km
13 months ago
21 Jul, 09:48
1.3
3 km North of Sampeyre
28 km North-West · 11 km
14 months ago
11 Jul, 04:11
1.0
2 km West of Pradleves
8 km North-West · 11 km
14 months ago
11 Jul, 02:20
1.0
2 km East of Pradleves
5 km North-West · 11 km
13 months ago
24 Jul, 04:39
0.5
1 km West of Marmora
18 km West · 10 km
13 months ago
27 Jul, 10:34

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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