All earthquakes
1.7
very light
EARTHQUAKE DETAILS

1 km South of Rocca San Casciano

103 months ago · 27 Dec, 11:19

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

Stronger than 78% of Italian events in the past year

Where

1 km South of Rocca San CascianoEarthquakes 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

16 events
Magnitude:lightweakmoderatestrong

The energy released

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

5.4kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×89 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 ≈ 13 s

Animation sped up ~2× compared to reality.

  • Forlì
    24 km from the epicentre
    first tremor in ~6 s
    main shaking in ~10 s
  • Faenza
    26 km from the epicentre
    first tremor in ~6 s
    main shaking in ~11 s
  • Cesena
    30 km from the epicentre
    first tremor in ~7 s
    main shaking in ~12 s
  • Imola
    38 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

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 (~13 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 (M2.4, 104 months ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

2.4
The mainshock
3 km North-West of Faenza
104 months ago · 7 Dec, 17:48
Activity in the area right now (30 km radius)
0
last 24 hours
5
last 7 days
13
last 30 days
7 before8 after
this quake
Strongest of the sequence2.4

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: 761 events in the last 11 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 · 31 km from here
XCompletely destructive: most buildings are destroyed.
17816.1
Faentino earthquake
4 April 1781 · 21 km from here
IX-XCompletely destructive: most buildings are destroyed.
16616.0
Appennino forlivese earthquake
22 March 1661 · 6 km from here
XCompletely destructive: most buildings are destroyed.
15426.0
Mugello earthquake
13 June 1542 · 37 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

Castel San Pietro Terme-Meldola

The epicentre lies about 14 km from Castel San Pietro Terme-Meldola, one of the seismic structures mapped by INGV geologists.

estimated maximum magnitude 6.5between 2 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

1.9
1 km South-East of Casola Valsenio
24 km North-West · 50 km
103 months ago
26 Dec, 01:35
1.6
6 km North of Premilcuore
6 km South-West · 25 km
103 months ago
24 Dec, 21:52
1.9
2 km West of Galeata
8 km South-East · 35 km
103 months ago
3 Jan, 03:56
1.6
5 km South of Bertinoro
24 km East · 9 km
103 months ago
19 Dec, 21:12
1.6
3 km North-West of Premilcuore
10 km South-West · 9 km
103 months ago
8 Jan, 14:26
1.1
5 km South-West of Galeata
10 km South · 9 km
102 months ago
13 Jan, 16:22
1.6
5 km South-West of Galeata
11 km South · 7 km
104 months ago
10 Dec, 04:08
1.4
4 km North of Santa Sofia
13 km South · 8 km
102 months ago
14 Jan, 12:33
1.3
5 km West of Sarsina
24 km South-East · 8 km
102 months ago
15 Jan, 19:31
2.4
3 km North-West of Faenza
28 km North · 18 km
104 months ago
7 Dec, 17:48

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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