All earthquakes
1.1
very light
EARTHQUAKE DETAILS

6 km South of Ameglia

37 months ago · 30 Jul, 08:23

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 39% of Italian events in the past year

Where

6 km South of AmegliaEarthquakes in the province of La SpeziaEarthquakes 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

10 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 ≈ 9 s

Animation sped up ~2× compared to reality.

  • Carrara
    15 km from the epicentre
    first tremor in ~3 s
    main shaking in ~5 s
  • La Spezia
    15 km from the epicentre
    first tremor in ~3 s
    main shaking in ~5 s
  • Massa
    17 km from the epicentre
    first tremor in ~3 s
    main shaking in ~5 s
  • Viareggio
    29 km from the epicentre
    first tremor in ~5 s
    main shaking in ~9 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?

Foreshock

In hindsight it was a foreshock: 37 months ago the same area had a stronger quake (M2.2). This can only be said after the fact — it was not predictable beforehand.

2.2
The mainshock
4 km East of Aulla
37 months ago · 19 Aug, 17:07
Activity in the area right now (30 km radius)
0
last 24 hours
2
last 7 days
8
last 30 days
4 before5 after
this quake
Strongest of the sequence2.2

How often does it happen here?

about every ~24 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 178 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.

19206.5
Garfagnana earthquake
7 September 1920 · 32 km from here
XCompletely destructive: most buildings are destroyed.
18346.0
Val di Taro-Lunigiana earthquake
14 February 1834 · 48 km from here
IXDestructive: many buildings partly or fully collapse.
18375.9
Lunigiana earthquake
11 April 1837 · 26 km from here
XCompletely destructive: most buildings are destroyed.
17405.6
Garfagnana earthquake
6 March 1740 · 43 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

Lunigiana

The epicentre lies about 17 km from Lunigiana, one of the seismic structures mapped by INGV geologists.

estimated maximum magnitude 7.0between 1 and 10 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
1 km South-West of Bolano
21 km North · 11 km
37 months ago
30 Jul, 05:04
1.9
2 km North-West of Bolano
23 km North-West · 10 km
38 months ago
24 Jul, 09:20
1.3
13 km West of Viareggio
24 km South-East · 4 km
38 months ago
24 Jul, 01:40
0.8
3 km South of Careggine
30 km East · 1 km
37 months ago
10 Aug, 09:01
0.9
3 km North-East of Fosdinovo
18 km North-East · 10 km
37 months ago
18 Aug, 21:25
1.5
5 km East of Aulla
22 km North-East · 7 km
37 months ago
18 Aug, 22:07
2.2
4 km East of Aulla
22 km North-East · 8 km
37 months ago
19 Aug, 17:07
1.6
4 km East of Aulla
23 km North · 8 km
37 months ago
19 Aug, 22:41
0.5
38 months ago
8 Jul, 01:49

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).

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