All earthquakes
1.3
very light
EARTHQUAKE DETAILS

12 km South-East of Bordighera

2 months ago · 4 Jul, 19:45

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

12 km South-East of BordigheraEarthquakes 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

6 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 ≈ 33 s

Animation sped up ~6× compared to reality.

  • Sanremo
    14 km from the epicentre
    first tremor in ~3 s
    main shaking in ~5 s
  • Cuneo
    81 km from the epicentre
    first tremor in ~14 s
    main shaking in ~23 s
  • Savona
    87 km from the epicentre
    first tremor in ~15 s
    main shaking in ~25 s
  • Genova
    116 km from the epicentre
    first tremor in ~19 s
    main shaking in ~33 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?

Foreshock

In hindsight it was a foreshock: 1 month 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
Mare di Corsica [Mare]
1 month ago · 23 Jul, 17:05
Activity in the area right now (30 km radius)
0
last 24 hours
1
last 7 days
2
last 30 days
1 before4 after
this quake
Strongest of the sequence1.7

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: 45 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 · 27 km from here
XCompletely destructive: most buildings are destroyed.
19636.0
Mar Ligure earthquake
19 July 1963 · 49 km from here
VIStrong: felt by everyone, many get scared; objects fall, first light damage to buildings.
18545.7
Liguria occidentale earthquake
29 December 1854 · 34 km from here
VII-VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
16185.6
Alpes Niçoises earthquake
18 January 1618 · 47 km from here
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 sits above this source area: the deep structure where this area's earthquakes can originate.

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
16 km South of Riva Ligure
6 km East · 10 km
2 months ago
11 Jul, 09:08
1.7
Mare di Corsica [Mare]
29 km South · 32 km
1 month ago
23 Jul, 17:05
1.7
Mare di Corsica [Mare]
29 km South · 32 km
1 month ago
23 Jul, 17:05
0.4
2 km South of Dolceacqua
23 km North-West · 5 km
28 days ago
28 Jul, 12:32
1.1
3 months ago
10 Jun, 08:34

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).

We use cookies to analyse site traffic and improve your experience.

Privacy PolicyCookie Policy