All earthquakes
1.6
very light
EARTHQUAKE DETAILS

M1.6 earthquake · 7 km East of Bergeggi (SV)

10 years ago · 21 Mar 2016, 12:00

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 74% of Italian events in the past year

Where

7 km East of BergeggiEarthquakes 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

4 events
Magnitude:lightweakmoderatestrong

The energy released

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

3.8kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×126 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 ≈ 22 s

Animation sped up ~4× compared to reality.

  • Savona
    11 km from the epicentre
    first tremor in ~2 s
    main shaking in ~3 s
  • Genova
    33 km from the epicentre
    first tremor in ~6 s
    main shaking in ~9 s
  • Sanremo
    75 km from the epicentre
    first tremor in ~12 s
    main shaking in ~21 s
  • Alessandria
    76 km from the epicentre
    first tremor in ~13 s
    main shaking in ~22 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

1 km
shallow

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

shallower than 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?

Aftershock

It is an aftershock: it follows a stronger quake (M1.8, 10 years ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

1.8
The mainshock
6 km East of Bergeggi
10 years ago · 15 Mar 2016, 16:29
Activity in the area right now (30 km radius)
1
last 24 hours
18
last 7 days
18
last 30 days
2 before1 after
this quake
Strongest of the sequence1.8

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: 51 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.

17675.0
Genovese earthquake
7 February 1767 · 37 km from here
VI-VIIVery strong: hard to stand; chimneys and roof tiles fall, serious damage to weaker buildings.
19684.9
Liguria occidentale earthquake
18 April 1968 · 44 km from here
12764.8
Monferrato earthquake
29 July 1276 · 44 km from here
V-VIStrong: felt by everyone, many get scared; objects fall, first light damage to buildings.
15374.6
Savona earthquake
November 1537 · 9 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 6 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

1.0
7 km East of Bergeggi
1 km North · 1 km
10 years ago
21 Mar 2016, 15:24
1.5
7 km East of Bergeggi
1 km North · 6 km
10 years ago
19 Mar 2016, 10:54
1.8
6 km East of Bergeggi
3 km North-West · 1 km
10 years ago
15 Mar 2016, 16:29

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).