All earthquakes
0.9
very light
EARTHQUAKE DETAILS

3 km East of Borgo a Mozzano

121 months ago · 21 Sept, 09:51

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 23% of Italian events in the past year

Where

3 km East of Borgo a MozzanoEarthquakes 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

20 events
Magnitude:lightweakmoderatestrong

The energy released

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

0.3kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×1,413 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.

  • Lucca
    13 km from the epicentre
    first tremor in ~2 s
    main shaking in ~4 s
  • Viareggio
    26 km from the epicentre
    first tremor in ~4 s
    main shaking in ~7 s
  • Pistoia
    28 km from the epicentre
    first tremor in ~5 s
    main shaking in ~8 s
  • Massa
    33 km from the epicentre
    first tremor in ~6 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

1 km
shallow

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

shallower than the area average (~13 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 (M2.0, 121 months ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

2.0
The mainshock
3 km West of Abetone Cutigliano
121 months ago · 14 Sept, 16:50
Activity in the area right now (30 km radius)
0
last 24 hours
3
last 7 days
10
last 30 days
12 before7 after
this quake
Strongest of the sequence2.0

How often does it happen here?

about every ~8 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 546 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 · 33 km from here
XCompletely destructive: most buildings are destroyed.
18375.9
Lunigiana earthquake
11 April 1837 · 38 km from here
XCompletely destructive: most buildings are destroyed.
17405.6
Garfagnana earthquake
6 March 1740 · 14 km from here
VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
19145.6
Lucchesia earthquake
27 October 1914 · 6 km from here
VIIVery strong: hard to stand; chimneys and roof tiles fall, serious damage to weaker buildings.

Source: Parametric Catalogue of Italian Earthquakes CPTI15 (INGV, CC BY 4.0).

The closest seismic structure

Garfagnana

The epicentre lies about 4 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

1.0
121 months ago
20 Sept, 20:30
1.4
3 km East of Borgo a Mozzano
0 km North-West · 1 km
121 months ago
23 Sept, 10:33
1.4
3 km South-East of Altopascio
22 km South-East · 10 km
121 months ago
15 Sept, 07:08
2.0
3 km West of Abetone Cutigliano
22 km North-East · 11 km
121 months ago
14 Sept, 16:50
1.3
121 months ago
13 Sept, 11:17
1.1
4 km North-West of Cascina
29 km South · 10 km
121 months ago
13 Sept, 06:00
1.9
121 months ago
29 Sept, 15:24
0.7
7 km West of San Marcello Piteglio
16 km North-East · 5 km
121 months ago
12 Sept, 09:27
1.1
3 km East of Vecchiano
23 km South-West · 9 km
120 months ago
4 Oct, 01:04
1.0
120 months ago
5 Oct, 21:33

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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