All earthquakes
1.8
very light
EARTHQUAKE DETAILS

4 km South-East of Bagno di Romagna

81 months ago · 21 Oct, 17:10

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 82% of Italian events in the past year

Where

4 km South-East of Bagno di RomagnaEarthquakes 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

34 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 ≈ 14 s

Animation sped up ~3× compared to reality.

  • Cesena
    33 km from the epicentre
    first tremor in ~6 s
    main shaking in ~10 s
  • Forlì
    41 km from the epicentre
    first tremor in ~7 s
    main shaking in ~12 s
  • Arezzo
    45 km from the epicentre
    first tremor in ~8 s
    main shaking in ~13 s
  • Rimini
    48 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

8 km
shallow

At only a few km deep the shaking is felt more sharply at the surface.

in line with the area average (~11 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 (M2.7, 81 months ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

2.7
The mainshock
4 km East of Chitignano
81 months ago · 15 Oct, 19:52
Activity in the area right now (30 km radius)
0
last 24 hours
2
last 7 days
23
last 30 days
16 before17 after
this quake
Strongest of the sequence2.7

How often does it happen here?

about every ~7 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 635 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 · 41 km from here
XCompletely destructive: most buildings are destroyed.
13526.3
Alta Valtiberina earthquake
25 December 1352 · 44 km from here
IXDestructive: many buildings partly or fully collapse.
17816.1
Faentino earthquake
4 April 1781 · 47 km from here
IX-XCompletely destructive: most buildings are destroyed.
16616.0
Appennino forlivese earthquake
22 March 1661 · 20 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 16 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

1.2
5 km North-West of Santa Sofia
15 km North-West · 9 km
81 months ago
21 Oct, 15:15
1.4
4 km North-East of Premilcuore
20 km North-West · 28 km
81 months ago
23 Oct, 10:26
1.5
3 km South-West of Galeata
16 km North-West · 32 km
81 months ago
26 Oct, 05:26
1.6
3 km South-West of Galeata
17 km North-West · 32 km
81 months ago
26 Oct, 05:26
0.7
4 km South-East of Galeata
13 km North-West · 10 km
81 months ago
26 Oct, 11:03
1.3
6 km North of San Godenzo
29 km West · 8 km
81 months ago
16 Oct, 10:56
0.7
81 months ago
27 Oct, 00:37
0.5
4 km West of Sansepolcro
29 km South-East · 14 km
81 months ago
27 Oct, 02:43
2.7
4 km East of Chitignano
22 km South · 11 km
81 months ago
15 Oct, 19:52
1.5
5 km East of Premilcuore
18 km North-West · 32 km
81 months ago
15 Oct, 14:31

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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