All earthquakes
1.7
very light
EARTHQUAKE DETAILS

M1.7 earthquake · 3 km West of Bertinoro (FC)

6 years ago · 27 Dec 2019, 01:31

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

3 km West of BertinoroEarthquakes 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

15 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 ≈ 11 s

Animation sped up ~2× compared to reality.

  • Forlì
    7 km from the epicentre
    first tremor in ~5 s
    main shaking in ~8 s
  • Cesena
    12 km from the epicentre
    first tremor in ~5 s
    main shaking in ~8 s
  • Faenza
    23 km from the epicentre
    first tremor in ~6 s
    main shaking in ~10 s
  • Ravenna
    26 km from the epicentre
    first tremor in ~6 s
    main shaking in ~11 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?

Foreshock

In hindsight it was a foreshock: 6 years ago the same area had a stronger quake (M2.7). This can only be said after the fact — it was not predictable beforehand.

2.7
The mainshock
12 km East of Ravenna
6 years ago · 25 Jan 2020, 00:17
Activity in the area right now (30 km radius)
0
last 24 hours
1
last 7 days
2
last 30 days
7 before7 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: 606 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.

17816.1
Faentino earthquake
4 April 1781 · 26 km from here
IX-XCompletely destructive: most buildings are destroyed.
16616.0
Appennino forlivese earthquake
22 March 1661 · 23 km from here
XCompletely destructive: most buildings are destroyed.
17686.0
Appennino forlivese earthquake
19 October 1768 · 29 km from here
IXDestructive: many buildings partly or fully collapse.
15846.0
Appennino forlivese earthquake
10 September 1584 · 35 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 sits above this source area: the deep structure where this area's earthquakes can originate.

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

1.2
3 km West of Sarsina
29 km South · 8 km
6 years ago
28 Dec 2019, 08:25
1.7
1 km East of Cervia
20 km North-East · 35 km
6 years ago
28 Dec 2019, 18:42
1.9
2 km South-East of Galeata
25 km South-West · 25 km
6 years ago
14 Dec 2019, 04:00
2.2
4 km South of Galeata
27 km South-West · 27 km
6 years ago
14 Dec 2019, 03:52
1.2
5 km West of Gambettola
15 km East · 24 km
6 years ago
12 Dec 2019, 14:19
2.3
6 km North-East of Forlimpopoli
10 km North-East · 19 km
6 years ago
10 Dec 2019, 17:31
1.5
4 km South-East of Rocca San Casciano
23 km South-West · 31 km
6 years ago
14 Jan 2020, 06:09
1.3
6 km South-West of Galeata
29 km South-West · 10 km
6 years ago
6 Dec 2019, 10:15
1.9
6 km East of Premilcuore
29 km South-West · 10 km
6 years ago
6 Dec 2019, 08:43
1.5
4 km South of Galeata
27 km South-West · 9 km
6 years ago
22 Jan 2020, 11:43

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).