All earthquakes
1.5
very light
EARTHQUAKE DETAILS

10 km South-East of Firenzuola

76 months ago · 9 Mar, 04:43

A very light earthquake, probably not felt by people. At this depth the shaking is felt, but rarely causes damage.

Stronger than 68% of Italian events in the past year

Where

10 km South-East of FirenzuolaEarthquakes in the province of FirenzeEarthquakes 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

61 events
Magnitude:lightweakmoderatestrong

The energy released

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

2.7kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×178 its energy
M1this quakeM3

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 ≈ 13 s

Animation sped up ~2× compared to reality.

  • Prato
    33 km from the epicentre
    first tremor in ~6 s
    main shaking in ~10 s
  • Firenze
    35 km from the epicentre
    first tremor in ~6 s
    main shaking in ~10 s
  • Imola
    43 km from the epicentre
    first tremor in ~7 s
    main shaking in ~13 s
  • Pistoia
    43 km from the epicentre
    first tremor in ~7 s
    main shaking in ~13 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
medium depth
1.1 times the height of Mount Everest

At this depth the shaking is felt, but rarely causes damage.

in line with 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?

Foreshock

In hindsight it was a foreshock: 76 months ago the same area had a stronger quake (M3.0). This can only be said after the fact — it was not predictable beforehand.

3.0
The mainshock
1 km North-East of Fontanelice
76 months ago · 31 Mar, 03:19
Activity in the area right now (30 km radius)
0
last 24 hours
6
last 7 days
21
last 30 days
20 before44 after
this quake
Strongest of the sequence3.0

How often does it happen here?

about every ~4 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 996 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.

19196.4
Mugello earthquake
29 June 1919 · 12 km from here
XCompletely destructive: most buildings are destroyed.
17816.1
Faentino earthquake
4 April 1781 · 36 km from here
IX-XCompletely destructive: most buildings are destroyed.
16616.0
Appennino forlivese earthquake
22 March 1661 · 38 km from here
XCompletely destructive: most buildings are destroyed.
15426.0
Mugello earthquake
13 June 1542 · 7 km from here
IXDestructive: many buildings partly or fully collapse.

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

The closest seismic structure

Mugello-Citta' di Castello-Leonessa

The epicentre lies about 3 km from Mugello-Citta' di Castello-Leonessa, one of the seismic structures mapped by INGV geologists.

estimated maximum magnitude 6.9between 1 and 8 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

0.7
76 months ago
8 Mar, 21:34
1.7
3 km East of Casola Valsenio
23 km North-East · 27 km
76 months ago
7 Mar, 23:46
1.4
2 km North of Premilcuore
30 km East · 9 km
76 months ago
6 Mar, 09:23
1.1
3 km South-West of Marradi
15 km East · 10 km
76 months ago
6 Mar, 07:34
1.0
3 km South of Tredozio
26 km East · 10 km
76 months ago
12 Mar, 08:12
1.2
76 months ago
12 Mar, 09:27
1.3
1 km North of Premilcuore
30 km East · 9 km
76 months ago
4 Mar, 21:26
1.9
2 km North of Scarperia e San Piero
12 km South-West · 9 km
76 months ago
13 Mar, 15:02
1.9
2 km North of Scarperia e San Piero
12 km South-West · 9 km
76 months ago
13 Mar, 15:02
2.0
2 km South-West of Monterenzio
25 km North · 22 km
76 months ago
18 Mar, 16:29

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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