All earthquakes
1.9
very light
EARTHQUAKE DETAILS

4 km North of Rossiglione

100 months ago · 2 Jun, 00:50

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 85% of Italian events in the past year

Where

4 km North of RossiglioneEarthquakes in the province of GenovaEarthquakes in Liguria

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

6 events
Magnitude:lightweakmoderatestrong

The energy released

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

11kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×45 its energy
M1this quakeM3

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 ≈ 15 s

Animation sped up ~3× compared to reality.

  • Genova
    24 km from the epicentre
    first tremor in ~4 s
    main shaking in ~7 s
  • Savona
    34 km from the epicentre
    first tremor in ~6 s
    main shaking in ~10 s
  • Alessandria
    36 km from the epicentre
    first tremor in ~6 s
    main shaking in ~11 s
  • Asti
    50 km from the epicentre
    first tremor in ~9 s
    main shaking in ~15 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 (~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 (M2.4, 101 months ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

2.4
The mainshock
1 km North-East of Sezzadio
101 months ago · 15 May, 20:05
Activity in the area right now (30 km radius)
0
last 24 hours
0
last 7 days
1
last 30 days
3 before2 after
this quake
Strongest of the sequence2.4

How often does it happen here?

about every ~2 months

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 69 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.

18285.7
Oltrepò Pavese earthquake
9 October 1828 · 41 km from here
VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
15415.3
Valle Scrivia earthquake
22 October 1541 · 28 km from here
VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
19455.1
Oltrepò Pavese earthquake
29 June 1945 · 46 km from here
VII-VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
16805.1
Valle Scrivia earthquake
30 April 1680 · 16 km from here
VIIVery strong: hard to stand; chimneys and roof tiles fall, serious damage to weaker buildings.

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

The closest seismic structure

Eastern Monferrato

The epicentre lies about 36 km from Eastern Monferrato, one of the seismic structures mapped by INGV geologists.

estimated maximum magnitude 6.4between 1 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

1.6
3 km West of Gavi
16 km North-East · 7 km
100 months ago
28 May, 16:29
1.2
11 km South-West of Genova
30 km South-East · 6 km
100 months ago
10 Jun, 19:47
0.7
3 km North of Rossiglione
1 km South · 9 km
100 months ago
18 Jun, 07:00
2.4
1 km North-East of Sezzadio
21 km North · 62 km
101 months ago
15 May, 20:05
2.1
2 km West of Rocca Grimalda
10 km North · 43 km
101 months ago
6 May, 09:22

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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