All earthquakes
0.5
very light
EARTHQUAKE DETAILS

2 km South-East of Portico e San Benedetto

78 months ago · 4 Jan, 07:07

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 3% of Italian events in the past year

Where

2 km South-East of Portico e San BenedettoEarthquakes 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

61 events
Magnitude:lightweakmoderatestrong

The energy released

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

0.1kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×5,623 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 ≈ 13 s

Animation sped up ~2× compared to reality.

  • Forlì
    36 km from the epicentre
    first tremor in ~6 s
    main shaking in ~10 s
  • Faenza
    36 km from the epicentre
    first tremor in ~6 s
    main shaking in ~10 s
  • Cesena
    41 km from the epicentre
    first tremor in ~7 s
    main shaking in ~12 s
  • Imola
    44 km from the epicentre
    first tremor in ~8 s
    main shaking in ~13 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

5 km
shallow

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

shallower 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?

Aftershock

It is an aftershock: it follows a stronger quake (M2.8, 79 months ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

2.8
The mainshock
5 km East of Castel del Rio
79 months ago · 29 Dec, 11:50
Activity in the area right now (30 km radius)
0
last 24 hours
2
last 7 days
9
last 30 days
39 before33 after
this quake
Strongest of the sequence2.8

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: 772 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 · 21 km from here
XCompletely destructive: most buildings are destroyed.
17816.1
Faentino earthquake
4 April 1781 · 29 km from here
IX-XCompletely destructive: most buildings are destroyed.
16616.0
Appennino forlivese earthquake
22 March 1661 · 14 km from here
XCompletely destructive: most buildings are destroyed.
15426.0
Mugello earthquake
13 June 1542 · 28 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 10 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

0.4
5 km North-West of Verghereto
29 km South-East · 10 km
78 months ago
4 Jan, 00:45
0.4
5 km North of Verghereto
29 km South-East · 9 km
78 months ago
4 Jan, 00:31
0.7
5 km North of Verghereto
29 km South-East · 9 km
78 months ago
4 Jan, 00:03
1.8
3 km South-East of Castel del Rio
28 km North-West · 10 km
78 months ago
5 Jan, 13:14
2.1
4 km South of Castel del Rio
27 km North-West · 8 km
78 months ago
5 Jan, 17:41
1.4
3 km South-East of Castel del Rio
28 km North-West · 9 km
78 months ago
5 Jan, 18:15
0.8
5 km East of Premilcuore
9 km East · 10 km
78 months ago
6 Jan, 01:29
0.9
5 km East of Premilcuore
10 km East · 8 km
79 months ago
1 Jan, 16:57
1.0
78 months ago
8 Jan, 04:12
1.3
4 km West of Palazzuolo sul Senio
23 km North-West · 7 km
78 months ago
8 Jan, 13:15

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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