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2.8
light
EARTHQUAKE DETAILS

M2.8 earthquake · 13 km East of Ravenna (RA)

6 years ago · 19 Apr 2020, 05:27

A light earthquake, rarely felt by people. At only a few km deep the shaking is felt more sharply at the surface.

Stronger than 97% of Italian events in the past year

Where

13 km East of RavennaEarthquakes in the province of RavennaEarthquakes in Emilia-Romagna

How far away could it be felt?

An estimate of how far people may have felt this quake.

  • up to ~5 km · felt only by some, at rest

The coloured rings on the map below show these distances.

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

4 events
Magnitude:lightweakmoderatestrong

The energy released

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

239kgof TNT equivalent
1.0 lightning bolt
M3
A magnitude 3 earthquake releases ×2 its energy
M2this quakeM4

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.

  • Ravenna
    13 km from the epicentre
    first tremor in ~3 s
    main shaking in ~5 s
  • Forlì
    32 km from the epicentre
    first tremor in ~6 s
    main shaking in ~10 s
  • Cesena
    37 km from the epicentre
    first tremor in ~6 s
    main shaking in ~11 s
  • Faenza
    38 km from the epicentre
    first tremor in ~7 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

10 km
shallow
1.1 times the height of Mount Everest

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

shallower than the area average (~22 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?

Mainshock

It is the strongest quake of its sequence: so far it has been followed by 2 aftershocks within 30 km. Aftershocks tend to fade in number and strength over time.

Activity in the area right now (30 km radius)
0
last 24 hours
1
last 7 days
2
last 30 days
1 before2 after
this quake
Strongest of the sequence2.4

How often does it happen here?

about every ~45 days

Within 50 km of this epicentre, a magnitude ≥ 2.5 earthquake has occurred on average this often: 95 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 · 46 km from here
IX-XCompletely destructive: most buildings are destroyed.
16885.8
Romagna earthquake
11 April 1688 · 31 km from here
IXDestructive: many buildings partly or fully collapse.
19165.8
Riminese earthquake
17 May 1916 · 47 km from here
VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
18755.7
Costa romagnola earthquake
17 March 1875 · 35 km from here
VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.

Source: Parametric Catalogue of Italian Earthquakes CPTI15 (INGV, CC BY 4.0).

The closest seismic structure

Malalbergo-Ravenna

The epicentre lies about 4 km from Malalbergo-Ravenna, one of the seismic structures mapped by INGV geologists.

estimated maximum magnitude 6.9between 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
4 km South-East of Ravenna
12 km South-West · 25 km
6 years ago
25 Apr 2020, 20:35
1.0
5 km South-West of Russi
26 km West · 25 km
6 years ago
8 May 2020, 05:17
2.4
3 km North-East of Cesenatico
24 km South · 43 km
6 years ago
23 Mar 2020, 15:49

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).