All earthquakes
0.5
very light
EARTHQUAKE DETAILS

4 km North-East of Fosciandora

50 months ago · 4 Aug, 02:02

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 3% of Italian events in the past year

Where

4 km North-East of FosciandoraEarthquakes 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

34 events
Magnitude:lightweakmoderatestrong

The energy released

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

0.1kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×5,623 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 ≈ 10 s

Animation sped up ~2× compared to reality.

  • Massa
    30 km from the epicentre
    first tremor in ~5 s
    main shaking in ~9 s
  • Lucca
    33 km from the epicentre
    first tremor in ~6 s
    main shaking in ~10 s
  • Carrara
    34 km from the epicentre
    first tremor in ~6 s
    main shaking in ~10 s
  • Pistoia
    35 km from the epicentre
    first tremor in ~6 s
    main shaking in ~10 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

6 km
shallow

At only a few km deep the shaking is felt more sharply at the surface.

shallower than the area average (~14 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 (M2.5, 50 months ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

2.5
The mainshock
5 km North-West of Abetone Cutigliano
50 months ago · 6 Jul, 12:19
Activity in the area right now (30 km radius)
0
last 24 hours
0
last 7 days
6
last 30 days
13 before20 after
this quake
Strongest of the sequence2.5

How often does it happen here?

about every ~5 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 804 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 · 19 km from here
XCompletely destructive: most buildings are destroyed.
15016.0
Modenese earthquake
5 June 1501 · 49 km from here
IXDestructive: many buildings partly or fully collapse.
18375.9
Lunigiana earthquake
11 April 1837 · 27 km from here
XCompletely destructive: most buildings are destroyed.
17405.6
Garfagnana earthquake
6 March 1740 · 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

Garfagnana

The epicentre sits above this source area: the deep structure where this area's earthquakes can originate.

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

1.0
2 km East of Borgo a Mozzano
19 km South · 1 km
50 months ago
4 Aug, 09:46
0.6
49 months ago
8 Aug, 01:21
1.0
2 km East of Borgo a Mozzano
21 km South · 1 km
49 months ago
8 Aug, 07:57
1.3
49 months ago
8 Aug, 16:06
1.3
2 km North-East of Montecreto
22 km North-East · 10 km
49 months ago
9 Aug, 17:19
1.0
4 km South of Montefiorino
19 km North-East · 10 km
50 months ago
29 Jul, 00:19
1.1
49 months ago
13 Aug, 17:41
0.8
49 months ago
13 Aug, 21:34
0.7
3 km West of Fosciandora
7 km South-West · 11 km
50 months ago
19 Jul, 05:08
1.3
4 km North of Lama Mocogno
26 km North-East · 15 km
50 months ago
18 Jul, 13:35

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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