All earthquakes
0.8
very light
EARTHQUAKE DETAILS

6 km North-East of Chiusi della Verna

120 months ago · 27 Jul, 08:31

A very light earthquake, probably not felt by people. At this depth the shaking is felt, but rarely causes damage.

Stronger than 16% of Italian events in the past year

Where

6 km North-East of Chiusi della VernaEarthquakes 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

53 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 ≈ 16 s

Animation sped up ~3× compared to reality.

  • Arezzo
    33 km from the epicentre
    first tremor in ~6 s
    main shaking in ~11 s
  • Cesena
    44 km from the epicentre
    first tremor in ~8 s
    main shaking in ~14 s
  • Forlì
    53 km from the epicentre
    first tremor in ~9 s
    main shaking in ~16 s
  • Rimini
    55 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

16 km
medium depth
1.8 times the height of Mount Everest

At this depth the shaking is felt, but rarely causes damage.

deeper than 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?

Foreshock

In hindsight it was a foreshock: 120 months ago the same area had a stronger quake (M2.3). This can only be said after the fact — it was not predictable beforehand.

2.3
The mainshock
5 km North of Verghereto
120 months ago · 4 Aug, 20:51
Activity in the area right now (30 km radius)
1
last 24 hours
5
last 7 days
27
last 30 days
30 before22 after
this quake
Strongest of the sequence2.3

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: 522 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 · 48 km from here
XCompletely destructive: most buildings are destroyed.
19196.4
Mugello earthquake
29 June 1919 · 45 km from here
XCompletely destructive: most buildings are destroyed.
13526.3
Alta Valtiberina earthquake
25 December 1352 · 34 km from here
IXDestructive: many buildings partly or fully collapse.
16616.0
Appennino forlivese earthquake
22 March 1661 · 31 km from here
XCompletely destructive: most buildings are destroyed.

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 7 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

1.0
120 months ago
31 Jul, 12:35
0.4
4 km West of Citerna
28 km South-East · 5 km
121 months ago
22 Jul, 12:15
0.7
121 months ago
22 Jul, 02:53
0.9
6 km East of Chiusi della Verna
6 km South-East · 10 km
121 months ago
21 Jul, 18:44
0.6
3 km East of Borgo Pace
29 km East · 6 km
120 months ago
1 Aug, 22:31
1.1
6 km South of Borgo Pace
30 km South-East · 9 km
120 months ago
2 Aug, 04:42
1.1
11 km West of Verghereto
2 km North-West · 10 km
120 months ago
2 Aug, 17:00
1.2
120 months ago
4 Aug, 16:54
2.3
5 km North of Verghereto
14 km North-East · 8 km
120 months ago
4 Aug, 20:51
0.8
5 km South-West of Sarsina
16 km North-East · 9 km
120 months ago
4 Aug, 21:46

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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