All earthquakes
1.2
very light
EARTHQUAKE DETAILS

2 km South of Pieve Santo Stefano

56 months ago · 28 Oct, 02:23

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 47% of Italian events in the past year

Where

2 km South of Pieve Santo StefanoEarthquakes in the province of ArezzoEarthquakes 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

35 events
Magnitude:lightweakmoderatestrong

The energy released

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

1.0kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×501 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 ≈ 18 s

Animation sped up ~3× compared to reality.

  • Arezzo
    26 km from the epicentre
    first tremor in ~5 s
    main shaking in ~8 s
  • Cesena
    50 km from the epicentre
    first tremor in ~9 s
    main shaking in ~15 s
  • Rimini
    55 km from the epicentre
    first tremor in ~9 s
    main shaking in ~16 s
  • Forlì
    61 km from the epicentre
    first tremor in ~10 s
    main shaking in ~18 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 (~10 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 (M2.6, 57 months ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

2.6
The mainshock
5 km West of Verghereto
57 months ago · 14 Oct, 19:34
Activity in the area right now (30 km radius)
0
last 24 hours
7
last 7 days
40
last 30 days
18 before16 after
this quake
Strongest of the sequence2.6

How often does it happen here?

about every ~9 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 485 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.

17816.5
Cagliese earthquake
3 June 1781 · 38 km from here
XCompletely destructive: most buildings are destroyed.
13526.3
Alta Valtiberina earthquake
25 December 1352 · 23 km from here
IXDestructive: many buildings partly or fully collapse.
16616.0
Appennino forlivese earthquake
22 March 1661 · 42 km from here
XCompletely destructive: most buildings are destroyed.
13896.0
Alta Valtiberina earthquake
18 October 1389 · 25 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 1 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

1.5
3 km South of Pieve Santo Stefano
1 km South-West · 10 km
56 months ago
28 Oct, 02:23
1.1
3 km South of Pieve Santo Stefano
1 km South-West · 9 km
56 months ago
28 Oct, 02:22
0.9
56 months ago
28 Oct, 02:24
0.9
56 months ago
27 Oct, 14:50
1.1
56 months ago
26 Oct, 05:14
0.6
3 km North-East of Verghereto
19 km North · 10 km
56 months ago
30 Oct, 04:44
0.7
56 months ago
25 Oct, 21:26
1.8
6 km South of Pieve Santo Stefano
4 km South-East · 10 km
56 months ago
25 Oct, 19:12
0.7
56 months ago
25 Oct, 19:02
0.9
56 months ago
25 Oct, 16:36

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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