All earthquakes
1.3
very light
EARTHQUAKE DETAILS

3 km West of Rialto

16 months ago · 25 Apr, 22:15

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 55% of Italian events in the past year

Where

3 km West of RialtoEarthquakes in the province of SavonaEarthquakes 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

10 events
Magnitude:lightweakmoderatestrong

The energy released

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

1.3kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×355 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 ≈ 17 s

Animation sped up ~3× compared to reality.

  • Savona
    21 km from the epicentre
    first tremor in ~4 s
    main shaking in ~7 s
  • Genova
    54 km from the epicentre
    first tremor in ~9 s
    main shaking in ~16 s
  • Sanremo
    57 km from the epicentre
    first tremor in ~10 s
    main shaking in ~17 s
  • Cuneo
    57 km from the epicentre
    first tremor in ~10 s
    main shaking in ~17 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
shallow
1.1 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 (~7 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?

Mainshock

It is the strongest quake of its sequence: so far it has been followed by 2 aftershocks within 30 km. Aftershocks tend to fade in number and strength over time.

Activity in the area right now (30 km radius)
0
last 24 hours
0
last 7 days
7
last 30 days
7 before2 after
this quake
Strongest of the sequence1.1

How often does it happen here?

about every ~4 months

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 32 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.

18876.3
Liguria occidentale earthquake
23 February 1887 · 42 km from here
XCompletely destructive: most buildings are destroyed.
18185.3
Liguria occidentale earthquake
23 February 1818 · 38 km from here
VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
19684.9
Liguria occidentale earthquake
18 April 1968 · 25 km from here
19194.9
Alpi Marittime earthquake
28 November 1919 · 37 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

Imperia Promontory

The epicentre lies about 26 km from Imperia Promontory, one of the seismic structures mapped by INGV geologists.

estimated maximum magnitude 7.4between 3 and 15 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 West of Rialto
1 km North · 10 km
16 months ago
25 Apr, 21:32
0.6
2 km North-West of Magliolo
2 km South-West · 9 km
16 months ago
25 Apr, 18:59
0.9
4 km West of Rialto
1 km North-West · 9 km
16 months ago
25 Apr, 18:00
0.7
4 km South-West of Bormida
1 km North-West · 9 km
16 months ago
26 Apr, 09:07
0.8
2 km North-East of Castelbianco
16 km South-West · 7 km
16 months ago
22 Apr, 11:05
0.9
0 km North-East of Zuccarello
16 km South-West · 6 km
16 months ago
22 Apr, 10:37
0.6
1 km North-West of Cisano sul Neva
17 km South-West · 5 km
16 months ago
15 May, 16:59
0.9
6 km North-East of Altare
19 km North-East · 8 km
17 months ago
2 Apr, 11:30
0.4
1 km South-East of Zuccarello
17 km South-West · 5 km
17 months ago
1 Apr, 11:53

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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