All earthquakes
1.1
very light
EARTHQUAKE DETAILS

M1.1 earthquake · 1 km North-West of Vasia (IM)

5 years ago · 10 Jul 2021, 10:57

A very light earthquake, probably not felt by people. At this depth the shaking is felt, but rarely causes damage.

Stronger than 39% of Italian events in the past year

Where

1 km North-West of VasiaEarthquakes 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

15 events
Magnitude:lightweakmoderatestrong

The energy released

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

0.7kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×708 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.

  • Sanremo
    18 km from the epicentre
    first tremor in ~3 s
    main shaking in ~6 s
  • Savona
    59 km from the epicentre
    first tremor in ~10 s
    main shaking in ~17 s
  • Cuneo
    60 km from the epicentre
    first tremor in ~10 s
    main shaking in ~17 s
  • Genova
    90 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
medium depth
1.1 times the height of Mount Everest

At this depth the shaking is felt, but rarely causes damage.

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?

Aftershock

It is an aftershock: it follows a stronger quake (M1.4, 5 years ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

1.4
The mainshock
17 km South of Costarainera
5 years ago · 9 Jul 2021, 20:36
Activity in the area right now (30 km radius)
2
last 24 hours
8
last 7 days
12
last 30 days
7 before7 after
this quake
Strongest of the sequence1.4

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.

18876.3
Liguria occidentale earthquake
23 February 1887 · 9 km from here
XCompletely destructive: most buildings are destroyed.
16185.6
Alpes Niçoises earthquake
18 January 1618 · 49 km from here
VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
18315.6
Liguria occidentale earthquake
26 May 1831 · 12 km from here
VIII-IXDestructive: many buildings partly or fully collapse.
18185.3
Liguria occidentale earthquake
23 February 1818 · 9 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 lies about 17 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

1.1
2 km North of Prelà
1 km West · 10 km
5 years ago
10 Jul 2021, 07:41
1.4
17 km South of Costarainera
28 km South · 10 km
5 years ago
9 Jul 2021, 20:36
1.4
1 km North-East of Bajardo
16 km West · 10 km
5 years ago
3 Jul 2021, 09:23
0.5
3 km West of Armo
17 km North · 12 km
5 years ago
19 Jul 2021, 12:04
0.8
3 km West of Armo
18 km North · 11 km
5 years ago
19 Jul 2021, 17:18
1.3
1 km West of Pigna
22 km West · 10 km
5 years ago
29 Jun 2021, 05:51
0.6
5 years ago
22 Jul 2021, 03:00
0.4
5 years ago
24 Jul 2021, 05:12
0.4
5 years ago
26 Jul 2021, 00:42
0.7
1 km North-West of Cisano sul Neva
23 km North-East · 1 km
5 years ago
30 Jul 2021, 16:59

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).