All earthquakes
1.0
very light
EARTHQUAKE DETAILS

2 km South-West of Serravalle Pistoiese

131 months ago · 20 Sept, 22:58

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 30% of Italian events in the past year

Where

2 km South-West of Serravalle PistoieseEarthquakes in the province of PistoiaEarthquakes 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

7 events
Magnitude:lightweakmoderatestrong

The energy released

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

0.5kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×1,000 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.

  • Pistoia
    15 km from the epicentre
    first tremor in ~3 s
    main shaking in ~5 s
  • Prato
    19 km from the epicentre
    first tremor in ~4 s
    main shaking in ~6 s
  • Lucca
    32 km from the epicentre
    first tremor in ~6 s
    main shaking in ~9 s
  • Firenze
    33 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

10 km
shallow
1.1 times the height of Mount Everest

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

in line with the area average (~12 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: 130 months ago the same area had a stronger quake (M2.9). This can only be said after the fact — it was not predictable beforehand.

2.9
The mainshock
3 km West of Pistoia
130 months ago · 10 Oct, 20:42
Activity in the area right now (30 km radius)
0
last 24 hours
3
last 7 days
4
last 30 days
1 before5 after
this quake
Strongest of the sequence2.9

How often does it happen here?

about every ~6 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 700 events in the last 11 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.

15426.0
Mugello earthquake
13 June 1542 · 45 km from here
IXDestructive: many buildings partly or fully collapse.
17405.6
Garfagnana earthquake
6 March 1740 · 38 km from here
VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
19145.6
Lucchesia earthquake
27 October 1914 · 22 km from here
VIIVery strong: hard to stand; chimneys and roof tiles fall, serious damage to weaker buildings.
14705.6
Appennino bolognese earthquake
11 April 1470 · 36 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 26 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

1.4
5 km East of Marliana
12 km North · 10 km
130 months ago
4 Oct, 10:45
1.2
6 km South of Abetone Cutigliano
27 km North-West · 11 km
130 months ago
7 Oct, 01:06
1.8
3 km East of Sambuca Pistoiese
27 km North-East · 13 km
130 months ago
7 Oct, 19:05
2.9
3 km West of Pistoia
14 km North · 35 km
130 months ago
10 Oct, 20:42
1.0
4 km North-East of Montespertoli
29 km South-East · 10 km
130 months ago
12 Oct, 04:30
2.2
2 km North-East of Agliana
13 km East · 54 km
132 months ago
25 Aug, 10:07

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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