All earthquakes
1.0
very light
EARTHQUAKE DETAILS

M1.0 earthquake · 16 km South of Bordighera (IM)

8 years ago · 3 Jun 2018, 16:14

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 31% of Italian events in the past year

Where

16 km South 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

4 events
Magnitude:lightweakmoderatestrong

The energy released

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

0.5kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×1,000 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 ≈ 35 s

Animation sped up ~7× compared to reality.

  • Sanremo
    20 km from the epicentre
    first tremor in ~4 s
    main shaking in ~6 s
  • Cuneo
    85 km from the epicentre
    first tremor in ~14 s
    main shaking in ~24 s
  • Savona
    93 km from the epicentre
    first tremor in ~16 s
    main shaking in ~27 s
  • Genova
    122 km from the epicentre
    first tremor in ~20 s
    main shaking in ~35 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

8 km
shallow

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?

Aftershock

It is an aftershock: it follows a stronger quake (M2.8, 8 years ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

2.8
The mainshock
Costa Ligure Occidentale (Imperia)
8 years ago · 3 Jun 2018, 03:47
Activity in the area right now (30 km radius)
0
last 24 hours
2
last 7 days
3
last 30 days
3 before0 after
this quake
Strongest of the sequence2.8

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: 39 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 · 33 km from here
XCompletely destructive: most buildings are destroyed.
19636.0
Mar Ligure earthquake
19 July 1963 · 48 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 · 28 km from here
VII-VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
16185.6
Alpes Niçoises earthquake
18 January 1618 · 48 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

2.8
Costa Ligure Occidentale (Imperia)
12 km South · 23 km
8 years ago
3 Jun 2018, 03:47
1.0
7 km South of Riva Ligure
17 km North-East · 11 km
8 years ago
20 May 2018, 09:34
0.5
3 km South-East of Pigna
28 km North · 10 km
8 years ago
17 May 2018, 16:31

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).