All earthquakes
1.4
very light
EARTHQUAKE DETAILS

M1.4 earthquake · 23 km South-East of Noli (SV)

8 years ago · 21 Jun 2018, 09:11

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

23 km South-East of NoliEarthquakes 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

7 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 ≈ 26 s

Animation sped up ~5× compared to reality.

  • Savona
    29 km from the epicentre
    first tremor in ~5 s
    main shaking in ~9 s
  • Genova
    41 km from the epicentre
    first tremor in ~7 s
    main shaking in ~12 s
  • Sanremo
    74 km from the epicentre
    first tremor in ~13 s
    main shaking in ~21 s
  • Alessandria
    92 km from the epicentre
    first tremor in ~15 s
    main shaking in ~26 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

10 km
shallow
1.1 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 (~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?

Foreshock

In hindsight it was a foreshock: 8 years ago the same area had a stronger quake (M2.1). This can only be said after the fact — it was not predictable beforehand.

2.1
The mainshock
Costa Ligure centro-occidentale (Savona)
8 years ago · 15 Jul 2018, 14:00
Activity in the area right now (30 km radius)
0
last 24 hours
2
last 7 days
2
last 30 days
4 before2 after
this quake
Strongest of the sequence2.1

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: 33 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.

19684.9
Liguria occidentale earthquake
18 April 1968 · 48 km from here
18964.9
Liguria occidentale earthquake
16 October 1896 · 36 km from here
VIStrong: felt by everyone, many get scared; objects fall, first light damage to buildings.
15374.6
Savona earthquake
November 1537 · 28 km from here
VIStrong: felt by everyone, many get scared; objects fall, first light damage to buildings.
15364.6
Genova earthquake
10 August 1536 · 43 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 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

1.5
Costa Ligure centro-occidentale (Savona)
23 km South-West · 17 km
8 years ago
19 Jun 2018, 05:35
1.3
20 km South-East of Noli
5 km West · 7 km
8 years ago
26 Jun 2018, 05:46
1.3
Costa Ligure centro-occidentale (Savona)
22 km South-East · 14 km
8 years ago
14 Jun 2018, 21:40
1.2
11 km South-West of Genova
30 km North-East · 6 km
8 years ago
10 Jun 2018, 19:47
1.0
Costa Ligure centro-occidentale (Savona)
8 km South · 11 km
8 years ago
7 Jun 2018, 12:06
2.1
Costa Ligure centro-occidentale (Savona)
7 km South-East · 11 km
8 years ago
15 Jul 2018, 14:00

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).