All earthquakes
1.9
very light
EARTHQUAKE DETAILS

3 km North of Polinago

53 months ago · 1 May, 20:05

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

Stronger than 85% of Italian events in the past year

Where

3 km North of PolinagoEarthquakes in the province of ModenaEarthquakes 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

38 events
Magnitude:lightweakmoderatestrong

The energy released

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

11kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×45 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 ≈ 16 s

Animation sped up ~3× compared to reality.

  • Reggio nell'Emilia
    34 km from the epicentre
    first tremor in ~7 s
    main shaking in ~12 s
  • Modena
    36 km from the epicentre
    first tremor in ~8 s
    main shaking in ~13 s
  • Carpi
    46 km from the epicentre
    first tremor in ~9 s
    main shaking in ~15 s
  • Pistoia
    47 km from the epicentre
    first tremor in ~9 s
    main shaking in ~16 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 (~15 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: 53 months ago the same area had a stronger quake (M2.2). This can only be said after the fact — it was not predictable beforehand.

2.2
The mainshock
2 km South-East of Prignano sulla Secchia
53 months ago · 5 May, 06:34
Activity in the area right now (30 km radius)
0
last 24 hours
4
last 7 days
9
last 30 days
13 before24 after
this quake
Strongest of the sequence2.2

How often does it happen here?

about every ~4 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 1139 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.

19206.5
Garfagnana earthquake
7 September 1920 · 43 km from here
XCompletely destructive: most buildings are destroyed.
15016.0
Modenese earthquake
5 June 1501 · 16 km from here
IXDestructive: many buildings partly or fully collapse.
17405.6
Garfagnana earthquake
6 March 1740 · 41 km from here
VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
15055.6
Bolognese earthquake
3 January 1505 · 42 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

Langhirano-Sassuolo

The epicentre lies about 6 km from Langhirano-Sassuolo, one of the seismic structures mapped by INGV geologists.

estimated maximum magnitude 6.8between 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

1.7
4 km North-West of Polinago
2 km West · 29 km
53 months ago
2 May, 02:03
1.9
4 km North-East of Polinago
2 km North-East · 28 km
53 months ago
2 May, 06:25
1.9
4 km North of Polinago
1 km North · 29 km
53 months ago
2 May, 06:45
1.1
4 km West of Pavullo nel Frignano
8 km South-East · 23 km
53 months ago
1 May, 02:52
1.5
3 km South-East of Formigine
21 km North-East · 37 km
53 months ago
3 May, 05:46
1.5
5 km West of Gaggio Montano
25 km South-East · 9 km
53 months ago
3 May, 18:24
1.7
4 km East of Montese
25 km South-East · 27 km
53 months ago
29 Apr, 18:33
1.3
1 km East of Castel d'Aiano
28 km South-East · 16 km
53 months ago
3 May, 23:45
1.9
3 km South of Prignano sulla Secchia
2 km North-West · 28 km
53 months ago
4 May, 21:12
1.4
4 km North of Polinago
2 km North-West · 32 km
53 months ago
5 May, 04:57

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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