All earthquakes
1.8
very light
EARTHQUAKE DETAILS

6 km South-West of Scarperia e San Piero

82 months ago · 9 Sept, 02:13

A very light earthquake, probably not felt by people. Being deep, it is felt less at the surface.

Stronger than 82% of Italian events in the past year

Where

6 km South-West of Scarperia e San PieroEarthquakes 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

16 events
Magnitude:lightweakmoderatestrong

The energy released

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

7.6kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×63 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 ≈ 24 s

Animation sped up ~5× compared to reality.

  • Prato
    15 km from the epicentre
    first tremor in ~10 s
    main shaking in ~18 s
  • Firenze
    19 km from the epicentre
    first tremor in ~10 s
    main shaking in ~18 s
  • Pistoia
    29 km from the epicentre
    first tremor in ~11 s
    main shaking in ~19 s
  • Imola
    61 km from the epicentre
    first tremor in ~14 s
    main shaking in ~24 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

60 km
deep
6.7 times the height of Mount Everest

Being deep, it is felt less at the surface.

deeper than 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?

Aftershock

It is an aftershock: it follows a stronger quake (M2.1, 83 months ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

2.1
The mainshock
9 km North-East of Scarperia e San Piero
83 months ago · 4 Sept, 09:05
Activity in the area right now (30 km radius)
0
last 24 hours
4
last 7 days
17
last 30 days
10 before5 after
this quake
Strongest of the sequence2.1

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: 959 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 · 18 km from here
XCompletely destructive: most buildings are destroyed.
15426.0
Mugello earthquake
13 June 1542 · 12 km from here
IXDestructive: many buildings partly or fully collapse.
17255.7
Appennino tosco-emiliano earthquake
29 October 1725 · 38 km from here
VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
14705.6
Appennino bolognese earthquake
11 April 1470 · 29 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 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

2.1
83 months ago
4 Sept, 09:05
1.4
5 km South-East of Firenzuola
21 km North-East · 8 km
83 months ago
4 Sept, 01:10
1.1
5 km South-East of Firenzuola
22 km North-East · 11 km
82 months ago
17 Sept, 10:19
1.0
6 km South-West of Firenzuola
16 km North-East · 11 km
83 months ago
30 Aug, 23:34
1.1
4 km East of Firenzuola
23 km North-East · 10 km
83 months ago
28 Aug, 11:15
0.7
82 months ago
21 Sept, 20:39
1.0
82 months ago
22 Sept, 00:36
0.8
83 months ago
26 Aug, 23:38
1.0
5 km South of Pistoia
30 km West · 11 km
82 months ago
25 Sept, 14:18
2.0
83 months ago
18 Aug, 15:50

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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