All earthquakes
1.3
very light
EARTHQUAKE DETAILS

0 km South-East of Viareggio

39 months ago · 26 Jun, 21:15

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 55% of Italian events in the past year

Where

0 km South-East of ViareggioEarthquakes in the province of LuccaEarthquakes in Toscana

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

11 events
Magnitude:lightweakmoderatestrong

The energy released

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

1.3kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×355 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 ≈ 7 s

Animation sped up ~1× compared to reality.

  • Viareggio
    0 km from the epicentre
    first tremor in ~1 s
    main shaking in ~2 s
  • Lucca
    17 km from the epicentre
    first tremor in ~3 s
    main shaking in ~5 s
  • Pisa
    21 km from the epicentre
    first tremor in ~4 s
    main shaking in ~6 s
  • Massa
    23 km from the epicentre
    first tremor in ~4 s
    main shaking in ~7 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 (M1.5, 39 months ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

1.5
The mainshock
3 km East of Gallicano
39 months ago · 23 Jun, 04:53
Activity in the area right now (30 km radius)
0
last 24 hours
4
last 7 days
67
last 30 days
4 before6 after
this quake
Strongest of the sequence1.5

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: 179 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 · 36 km from here
XCompletely destructive: most buildings are destroyed.
18466.0
Colline Pisane earthquake
14 August 1846 · 50 km from here
XCompletely destructive: most buildings are destroyed.
18375.9
Lunigiana earthquake
11 April 1837 · 36 km from here
XCompletely destructive: most buildings are destroyed.
17405.6
Garfagnana earthquake
6 March 1740 · 30 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

Garfagnana

The epicentre lies about 27 km from Garfagnana, one of the seismic structures mapped by INGV geologists.

estimated maximum magnitude 6.9between 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

1.5
3 km East of Gallicano
28 km North-East · 54 km
39 months ago
23 Jun, 04:53
0.8
6 km North-East of Vecchiano
13 km East · 10 km
39 months ago
17 Jun, 04:22
0.5
2 km North-West of Forte dei Marmi
16 km North-West · 8 km
38 months ago
8 Jul, 01:49
1.1
38 months ago
12 Jul, 10:46
1.1
38 months ago
14 Jul, 10:46
0.9
39 months ago
8 Jun, 09:58
0.8
4 km North-East of Massarosa
10 km East · 10 km
38 months ago
16 Jul, 01:30
0.9
39 months ago
6 Jun, 07:09
0.8
38 months ago
20 Jul, 10:36
1.3
13 km West of Viareggio
13 km West · 4 km
38 months ago
24 Jul, 01:40

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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