All earthquakes
0.4
very light
EARTHQUAKE DETAILS

2 km South of Dolceacqua

28 days ago · 28 Jul, 12:32

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 1% of Italian events in the past year

Where

2 km South of DolceacquaEarthquakes in the province of ImperiaEarthquakes 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

5 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 ×7,943 its energy
M-1this quakeM1

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 ≈ 34 s

Animation sped up ~6× compared to reality.

  • Sanremo
    15 km from the epicentre
    first tremor in ~3 s
    main shaking in ~5 s
  • Cuneo
    62 km from the epicentre
    first tremor in ~10 s
    main shaking in ~18 s
  • Savona
    86 km from the epicentre
    first tremor in ~14 s
    main shaking in ~25 s
  • Genova
    117 km from the epicentre
    first tremor in ~20 s
    main shaking in ~34 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

5 km
shallow

At only a few km deep the shaking is felt more sharply at the surface.

in line with the area average (~8 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 (M1.3, 2 months ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

1.3
The mainshock
12 km South-East of Bordighera
2 months ago · 4 Jul, 19:45
Activity in the area right now (30 km radius)
0
last 24 hours
1
last 7 days
3
last 30 days
2 before2 after
nowthis quake
Strongest of the sequence1.3

How often does it happen here?

about every ~3 months

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 55 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 · 32 km from here
XCompletely destructive: most buildings are destroyed.
15645.8
Lantosque earthquake
20 July 1564 · 31 km from here
VIII-IXDestructive: many buildings partly or fully collapse.
16445.7
Alpes Niçoises earthquake
15 February 1644 · 32 km from here
VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
18545.7
Liguria occidentale earthquake
29 December 1854 · 48 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

Imperia Promontory

The epicentre lies about 19 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

0.9
17 km North-West of Rocchetta Nervina
21 km North-West · 10 km
19 days ago
6 Aug, 08:01
1.1
16 km South of Riva Ligure
28 km South-East · 10 km
2 months ago
11 Jul, 09:08
0.4
1 km North-East of Ceriana
16 km East · 9 km
6 days ago
19 Aug, 06:31
1.3
12 km South-East of Bordighera
23 km South-East · 9 km
2 months ago
4 Jul, 19:45

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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