All earthquakes
1.5
very light
EARTHQUAKE DETAILS

4 km West of Barberino Tavarnelle

129 months ago · 26 Oct, 07:26

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 68% of Italian events in the past year

Where

4 km West of Barberino TavarnelleEarthquakes 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

9 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 ≈ 16 s

Animation sped up ~3× compared to reality.

  • Siena
    28 km from the epicentre
    first tremor in ~5 s
    main shaking in ~9 s
  • Firenze
    30 km from the epicentre
    first tremor in ~5 s
    main shaking in ~9 s
  • Prato
    41 km from the epicentre
    first tremor in ~7 s
    main shaking in ~12 s
  • Pistoia
    57 km from the epicentre
    first tremor in ~10 s
    main shaking in ~16 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

9 km
shallow
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 (~9 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 (M1.6, 130 months ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

1.6
The mainshock
6 km South-East of San Casciano in Val di Pesa
130 months ago · 22 Oct, 06:06
Activity in the area right now (30 km radius)
0
last 24 hours
0
last 7 days
1
last 30 days
3 before5 after
this quake
Strongest of the sequence1.6

How often does it happen here?

about every ~13 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 328 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.

18466.0
Colline Pisane earthquake
14 August 1846 · 48 km from here
XCompletely destructive: most buildings are destroyed.
15586.0
Valdarno superiore earthquake
13 April 1558 · 34 km from here
IXDestructive: many buildings partly or fully collapse.
14145.7
Colline Metallifere earthquake
7 August 1414 · 28 km from here
VII-VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
12935.6
Pistoia earthquake
March 1293 · 50 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

Mugello-Citta' di Castello-Leonessa

The epicentre lies about 48 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

1.6
130 months ago
22 Oct, 06:06
1.2
4 km North-East of Castelfiorentino
20 km North-West · 12 km
130 months ago
21 Oct, 17:52
1.2
5 km West of Greve in Chianti
14 km North-East · 7 km
129 months ago
5 Nov, 14:26
1.3
129 months ago
7 Nov, 12:52
1.0
130 months ago
12 Oct, 04:30
1.5
0 km South-West of San Gimignano
11 km South-West · 7 km
129 months ago
20 Nov, 16:26
1.5
4 km South-West of San Gimignano
15 km South-West · 8 km
129 months ago
22 Nov, 08:15
0.6
128 months ago
25 Nov, 03:15

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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