All earthquakes
0.8
very light
EARTHQUAKE DETAILS

6 km South-East of Pieve Santo Stefano

83 months ago · 2 Sept, 21:32

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 16% of Italian events in the past year

Where

6 km South-East 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

28 events
Magnitude:lightweakmoderatestrong

The energy released

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

0.2kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×1,995 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
    27 km from the epicentre
    first tremor in ~5 s
    main shaking in ~8 s
  • Cesena
    51 km from the epicentre
    first tremor in ~9 s
    main shaking in ~15 s
  • Rimini
    54 km from the epicentre
    first tremor in ~9 s
    main shaking in ~16 s
  • Perugia
    62 km from the epicentre
    first tremor in ~11 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 (~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 (M1.8, 83 months ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

1.8
The mainshock
3 km South-East of Mercatello sul Metauro
83 months ago · 10 Aug, 07:12
Activity in the area right now (30 km radius)
2
last 24 hours
10
last 7 days
67
last 30 days
13 before14 after
this quake
Strongest of the sequence1.8

How often does it happen here?

about every ~8 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 514 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.

17816.5
Cagliese earthquake
3 June 1781 · 33 km from here
XCompletely destructive: most buildings are destroyed.
13526.3
Alta Valtiberina earthquake
25 December 1352 · 20 km from here
IXDestructive: many buildings partly or fully collapse.
16616.0
Appennino forlivese earthquake
22 March 1661 · 45 km from here
XCompletely destructive: most buildings are destroyed.
13896.0
Alta Valtiberina earthquake
18 October 1389 · 20 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

1.1
83 months ago
2 Sept, 21:23
1.0
6 km South-West of Città di Castello
23 km South-East · 10 km
83 months ago
2 Sept, 21:45
1.2
5 km North of Pietralunga
29 km South-East · 7 km
83 months ago
1 Sept, 01:24
0.5
82 months ago
10 Sept, 19:16
1.2
2 km North-East of Sansepolcro
7 km South-East · 10 km
82 months ago
10 Sept, 19:31
1.1
6 km West of Pietralunga
30 km South-East · 7 km
82 months ago
10 Sept, 20:34
1.2
5 km North-West of Sansepolcro
2 km South-East · 10 km
82 months ago
11 Sept, 07:18
0.3
6 km South-West of Apecchio
27 km South-East · 10 km
82 months ago
12 Sept, 05:04
1.4
3 km South of Sestino
15 km East · 10 km
83 months ago
22 Aug, 21:11
1.2
5 km South-East of Bagno di Romagna
24 km North-West · 20 km
82 months ago
14 Sept, 07:15

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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