All earthquakes
1.6
very light
EARTHQUAKE DETAILS

5 km East of Rocca San Casciano

38 months ago · 23 Apr, 18:23

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

Stronger than 73% of Italian events in the past year

Where

5 km East 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

29 events
Magnitude:lightweakmoderatestrong

The energy released

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

3.8kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×126 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.

  • Forlì
    21 km from the epicentre
    first tremor in ~6 s
    main shaking in ~10 s
  • Cesena
    25 km from the epicentre
    first tremor in ~6 s
    main shaking in ~11 s
  • Faenza
    26 km from the epicentre
    first tremor in ~6 s
    main shaking in ~11 s
  • Imola
    40 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 (~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 (M2.7, 38 months ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

2.7
The mainshock
4 km South of Rocca San Casciano
38 months ago · 23 Apr, 18:17
Activity in the area right now (30 km radius)
0
last 24 hours
3
last 7 days
10
last 30 days
21 before7 after
this quake
Strongest of the sequence2.7

How often does it happen here?

about every ~6 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 748 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 · 36 km from here
XCompletely destructive: most buildings are destroyed.
17816.1
Faentino earthquake
4 April 1781 · 23 km from here
IX-XCompletely destructive: most buildings are destroyed.
16616.0
Appennino forlivese earthquake
22 March 1661 · 4 km from here
XCompletely destructive: most buildings are destroyed.
15426.0
Mugello earthquake
13 June 1542 · 42 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 10 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

1.5
5 km North of Galeata
2 km South-East · 29 km
38 months ago
23 Apr, 18:22
2.0
38 months ago
23 Apr, 18:20
1.8
38 months ago
23 Apr, 18:19
2.7
38 months ago
23 Apr, 18:17
1.8
38 months ago
23 Apr, 18:33
1.2
38 months ago
23 Apr, 18:06
0.9
4 km North of Bagno di Romagna
17 km South · 15 km
38 months ago
20 Apr, 15:44
1.2
3 km North of Bagno di Romagna
18 km South · 15 km
38 months ago
20 Apr, 09:45
1.2
38 months ago
27 Apr, 05:00
0.9
2 km East of Bagno di Romagna
22 km South · 15 km
38 months ago
19 Apr, 20:33

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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