All earthquakes
1.1
very light
EARTHQUAKE DETAILS

4 km West of Monterosso Grana

98 months ago · 30 Jul, 01:05

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

Stronger than 39% of Italian events in the past year

Where

4 km West 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

28 events
Magnitude:lightweakmoderatestrong

The energy released

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

0.7kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×708 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
    23 km from the epicentre
    first tremor in ~4 s
    main shaking in ~7 s
  • Sanremo
    73 km from the epicentre
    first tremor in ~12 s
    main shaking in ~21 s
  • Moncalieri
    75 km from the epicentre
    first tremor in ~13 s
    main shaking in ~22 s
  • Torino
    88 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

10 km
medium depth
1.2 times the height of Mount Everest

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

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?

Aftershock

It is an aftershock: it follows a stronger quake (M3.2, 99 months ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

3.2
The mainshock
2 km West of Stroppo
99 months ago · 17 Jul, 20:13
Activity in the area right now (30 km radius)
2
last 24 hours
3
last 7 days
10
last 30 days
14 before13 after
this quake
Strongest of the sequence3.2

How often does it happen here?

about every ~16 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 260 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 · 43 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 25 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

0.5
3 km East of Pradleves
6 km North-East · 9 km
98 months ago
29 Jul, 23:23
1.3
3 km South of Monterosso Grana
5 km South-East · 12 km
98 months ago
29 Jul, 15:05
0.7
2 km South-West of Stroppo
18 km North-West · 10 km
98 months ago
2 Aug, 16:25
3.0
2 km South of Elva
22 km North-West · 17 km
98 months ago
3 Aug, 03:21
0.6
2 km South-East of Pradleves
5 km North-East · 10 km
98 months ago
4 Aug, 06:32
0.9
3 km North of Pradleves
9 km North · 12 km
99 months ago
24 Jul, 13:40
1.4
4 km South-West of Stroppo
19 km North-West · 10 km
99 months ago
22 Jul, 06:50
1.1
4 km South-West of Melle
17 km North · 8 km
99 months ago
20 Jul, 12:54
1.3
6 km East of Sambuco
9 km West · 9 km
99 months ago
18 Jul, 20:55
1.4
0 km South-East of Stroppo
19 km North-West · 10 km
99 months ago
17 Jul, 20:28

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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