All earthquakes
1.4
very light
EARTHQUAKE DETAILS

M1.4 offshore earthquake

10 years ago · 5 Oct 2016, 10:00

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 63% of Italian events in the past year

Where

Nearest Italian town: Noli (SV)Earthquakes in the province of SavonaEarthquakes in Liguria

Epicentre at sea

The epicentre is at sea: for the same magnitude, the shaking is felt less on land, because the energy fades along the way before reaching the coast.

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.

1.9kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×251 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 ≈ 27 s

Animation sped up ~5× compared to reality.

  • Savona
    37 km from the epicentre
    first tremor in ~6 s
    main shaking in ~11 s
  • Genova
    47 km from the epicentre
    first tremor in ~8 s
    main shaking in ~14 s
  • Sanremo
    75 km from the epicentre
    first tremor in ~13 s
    main shaking in ~22 s
  • La Spezia
    93 km from the epicentre
    first tremor in ~16 s
    main shaking in ~27 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 (~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?

Foreshock

In hindsight it was a foreshock: 9 years 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
21 km East of Bergeggi
9 years ago · 17 Oct 2016, 08:53
Activity in the area right now (30 km radius)
0
last 24 hours
2
last 7 days
2
last 30 days
1 before3 after
this quake
Strongest of the sequence1.7

How often does it happen here?

about every ~5 months

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 30 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.

18964.9
Liguria occidentale earthquake
16 October 1896 · 28 km from here
VIStrong: felt by everyone, many get scared; objects fall, first light damage to buildings.
15374.6
Savona earthquake
November 1537 · 35 km from here
VIStrong: felt by everyone, many get scared; objects fall, first light damage to buildings.
15364.6
Genova earthquake
10 August 1536 · 48 km from here
VIStrong: felt by everyone, many get scared; objects fall, first light damage to buildings.
11824.6
Genova earthquake
15 August 1182 · 48 km from here
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 1 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

1.3
4 km South-East of Bergeggi
26 km North-West · 1 km
10 years ago
7 Oct 2016, 11:44
1.7
21 km East of Bergeggi
18 km North · 12 km
9 years ago
17 Oct 2016, 08:53
0.9
3 km South-East of Bergeggi
28 km North-West · 1 km
9 years ago
19 Oct 2016, 10:23
1.7
14 km East of Albenga
24 km West · 7 km
10 years ago
20 Sept 2016, 07:28

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).