All earthquakes
1.8
very light
EARTHQUAKE DETAILS

M1.8 earthquake · 5 km North-East of Vigarano Mainarda (FE)

9 years ago · 7 Apr 2017, 22:46

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 82% of Italian events in the past year

Where

5 km North-East of Vigarano MainardaEarthquakes in the province of FerraraEarthquakes 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.

7.6kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×63 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 ≈ 15 s

Animation sped up ~3× compared to reality.

  • Ferrara
    12 km from the epicentre
    first tremor in ~3 s
    main shaking in ~4 s
  • Rovigo
    29 km from the epicentre
    first tremor in ~5 s
    main shaking in ~9 s
  • Bologna
    45 km from the epicentre
    first tremor in ~8 s
    main shaking in ~13 s
  • Carpi
    51 km from the epicentre
    first tremor in ~9 s
    main shaking in ~15 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

8 km
shallow

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

in line with 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?

Foreshock

In hindsight it was a foreshock: 9 years ago the same area had a stronger quake (M3.2). This can only be said after the fact — it was not predictable beforehand.

3.2
The mainshock
4 km North-East of Terre del Reno
9 years ago · 26 Apr 2017, 21:15
Activity in the area right now (30 km radius)
0
last 24 hours
0
last 7 days
2
last 30 days
1 before14 after
this quake
Strongest of the sequence3.2

How often does it happen here?

about every ~20 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 219 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.

20126.1
Pianura emiliana earthquake
20 May 2012 · 23 km from here
VIIVery strong: hard to stand; chimneys and roof tiles fall, serious damage to weaker buildings.
20125.9
Pianura emiliana earthquake
29 May 2012 · 39 km from here
VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
15055.6
Bolognese earthquake
3 January 1505 · 48 km from here
VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
20125.5
Pianura emiliana earthquake
29 May 2012 · 45 km from here

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

The closest seismic structure

Poggio Rusco-Migliarino

The epicentre sits above this source area: the deep structure where this area's earthquakes can originate.

estimated maximum magnitude 6.8between 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

2.0
2 km South-West of Bondeno
15 km West · 8 km
9 years ago
6 Apr 2017, 21:54
2.6
4 km North of Finale Emilia
21 km West · 10 km
9 years ago
13 Apr 2017, 00:42
2.6
3 km North of Finale Emilia
22 km West · 7 km
9 years ago
13 Apr 2017, 02:14
2.6
5 km North of Finale Emilia
24 km West · 4 km
9 years ago
13 Apr 2017, 18:12
2.1
2 km North of Finale Emilia
22 km West · 7 km
9 years ago
20 Apr 2017, 21:29
2.1
9 years ago
24 Apr 2017, 09:06
3.1
9 years ago
26 Apr 2017, 18:46
2.6
4 km East of Terre del Reno
11 km South-West · 8 km
9 years ago
26 Apr 2017, 18:46
3.2
9 years ago
26 Apr 2017, 21:15
2.6
4 km North-East of Terre del Reno
10 km South-West · 8 km
9 years ago
26 Apr 2017, 21:15

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).