All earthquakes
1.3
very light
EARTHQUAKE DETAILS

3 km North-West of Tredozio

118 months ago · 17 Oct, 08:24

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

Stronger than 54% of Italian events in the past year

Where

3 km North-West of TredozioEarthquakes in the province of Forlì-CesenaEarthquakes in Emilia-Romagna

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.

1.3kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×355 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 ≈ 14 s

Animation sped up ~3× compared to reality.

  • Faenza
    27 km from the epicentre
    first tremor in ~6 s
    main shaking in ~11 s
  • Forlì
    30 km from the epicentre
    first tremor in ~7 s
    main shaking in ~11 s
  • Imola
    35 km from the epicentre
    first tremor in ~7 s
    main shaking in ~12 s
  • Cesena
    39 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

27 km
medium depth
3 times the height of Mount Everest

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

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?

Foreshock

In hindsight it was a foreshock: 117 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
4 km North-West of Tredozio
117 months ago · 9 Nov, 01:44
Activity in the area right now (30 km radius)
0
last 24 hours
4
last 7 days
14
last 30 days
17 before10 after
this quake
Strongest of the sequence2.3

How often does it happen here?

about every ~5 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 825 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 · 24 km from here
XCompletely destructive: most buildings are destroyed.
17816.1
Faentino earthquake
4 April 1781 · 20 km from here
IX-XCompletely destructive: most buildings are destroyed.
16616.0
Appennino forlivese earthquake
22 March 1661 · 15 km from here
XCompletely destructive: most buildings are destroyed.
15426.0
Mugello earthquake
13 June 1542 · 29 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 17 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

1.6
6 km North-West of Tredozio
3 km North · 27 km
118 months ago
17 Oct, 08:38
0.6
3 km West of Premilcuore
11 km South · 9 km
118 months ago
17 Oct, 04:46
1.3
4 km East of Galeata
21 km South-East · 22 km
118 months ago
15 Oct, 03:10
1.1
118 months ago
12 Oct, 17:25
1.3
3 km South-West of Bagno di Romagna
29 km South-East · 14 km
118 months ago
12 Oct, 08:09
1.5
4 km South-West of Bagno di Romagna
29 km South-East · 13 km
118 months ago
12 Oct, 06:33
1.2
3 km South-West of Bagno di Romagna
29 km South-East · 14 km
118 months ago
12 Oct, 06:14
0.9
5 km West of Sarsina
30 km South-East · 9 km
117 months ago
22 Oct, 15:12
1.6
2 km North-West of Casola Valsenio
19 km North-West · 16 km
117 months ago
23 Oct, 05:24
1.1
117 months ago
25 Oct, 08:57

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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