All earthquakes
1.9
very light
EARTHQUAKE DETAILS

3 km East of Vernio

21 months ago · 16 Dec, 09:37

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 85% of Italian events in the past year

Where

3 km East of VernioEarthquakes in the province of PratoEarthquakes 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

44 events
Magnitude:lightweakmoderatestrong

The energy released

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

11kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×45 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 ≈ 14 s

Animation sped up ~3× compared to reality.

  • Prato
    21 km from the epicentre
    first tremor in ~4 s
    main shaking in ~7 s
  • Pistoia
    24 km from the epicentre
    first tremor in ~4 s
    main shaking in ~7 s
  • Firenze
    32 km from the epicentre
    first tremor in ~6 s
    main shaking in ~10 s
  • Bologna
    50 km from the epicentre
    first tremor in ~8 s
    main shaking in ~14 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

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

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?

Aftershock

It is an aftershock: it follows a stronger quake (M2.8, 22 months ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

2.8
The mainshock
5 km West of Gaggio Montano
22 months ago · 20 Nov, 19:04
Activity in the area right now (30 km radius)
1
last 24 hours
2
last 7 days
8
last 30 days
17 before26 after
this quake
Strongest of the sequence2.8

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: 978 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.

19196.4
Mugello earthquake
29 June 1919 · 27 km from here
XCompletely destructive: most buildings are destroyed.
15426.0
Mugello earthquake
13 June 1542 · 18 km from here
IXDestructive: many buildings partly or fully collapse.
17255.7
Appennino tosco-emiliano earthquake
29 October 1725 · 35 km from here
VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
19145.6
Lucchesia earthquake
27 October 1914 · 50 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

Mugello-Citta' di Castello-Leonessa

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

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
21 months ago
11 Dec, 16:18
1.6
3 km West of Alto Reno Terme
23 km West · 11 km
21 months ago
10 Dec, 02:39
2.7
21 months ago
10 Dec, 02:00
0.9
21 months ago
9 Dec, 10:21
0.4
0 km North-East of Pistoia
23 km West · 9 km
21 months ago
7 Dec, 12:04
1.4
20 months ago
25 Dec, 19:29
1.6
3 km North-East of Montale
14 km South-West · 50 km
20 months ago
26 Dec, 00:29
1.0
4 km West of Alto Reno Terme
24 km West · 14 km
21 months ago
5 Dec, 22:18
1.4
20 months ago
27 Dec, 14:58
1.5
3 km North-East of Gaggio Montano
24 km North-West · 11 km
20 months ago
29 Dec, 22:51

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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