All earthquakes
0.8
very light
EARTHQUAKE DETAILS

4 km South of Pavullo nel Frignano

4 months ago · 9 May, 20:51

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

Stronger than 16% of Italian events in the past year

Where

4 km South of Pavullo nel FrignanoEarthquakes 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

21 events
Magnitude:lightweakmoderatestrong

The energy released

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

0.2kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×1,995 its energy
M0this quakeM2

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.

  • Pistoia
    35 km from the epicentre
    first tremor in ~6 s
    main shaking in ~11 s
  • Bologna
    44 km from the epicentre
    first tremor in ~8 s
    main shaking in ~14 s
  • Modena
    45 km from the epicentre
    first tremor in ~8 s
    main shaking in ~14 s
  • Reggio nell'Emilia
    47 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

18 km
medium depth
2 times the height of Mount Everest

At this depth the shaking is felt, but rarely causes damage.

in line with the area average (~14 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 (M2.4, 4 months ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

2.4
The mainshock
5 km East of Toano
4 months ago · 22 Apr, 02:06
Activity in the area right now (30 km radius)
0
last 24 hours
6
last 7 days
14
last 30 days
13 before7 after
this quake
Strongest of the sequence2.4

How often does it happen here?

about every ~5 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 877 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 · 47 km from here
XCompletely destructive: most buildings are destroyed.
15016.0
Modenese earthquake
5 June 1501 · 24 km from here
IXDestructive: many buildings partly or fully collapse.
17405.6
Garfagnana earthquake
6 March 1740 · 38 km from here
VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
19145.6
Lucchesia earthquake
27 October 1914 · 48 km from here
VIIVery strong: hard to stand; chimneys and roof tiles fall, serious damage to weaker buildings.

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

The closest seismic structure

Langhirano-Sassuolo

The epicentre lies about 14 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 months ago
8 May, 13:21
2.3
3 km East of Pavullo nel Frignano
6 km North-East · 30 km
4 months ago
4 May, 11:38
1.8
2 km West of Prignano sulla Secchia
20 km North-West · 33 km
3 months ago
15 May, 19:13
1.2
3 months ago
18 May, 17:53
1.8
4 months ago
29 Apr, 03:44
1.2
3 km South-East of Polinago
10 km North-West · 24 km
3 months ago
23 May, 12:58
1.1
2 km South of Riolunato
18 km South-West · 10 km
3 months ago
24 May, 05:50
1.0
3 months ago
27 May, 02:44
2.4
5 km East of Toano
22 km West · 22 km
4 months ago
22 Apr, 02:06
2.1
4 months ago
22 Apr, 02:03

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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