All earthquakes
1.8
very light
EARTHQUAKE DETAILS

6 km North of Frassinoro

9 months ago · 9 Dec, 17:24

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

6 km North of FrassinoroEarthquakes 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

11 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 ≈ 14 s

Animation sped up ~3× compared to reality.

  • Massa
    36 km from the epicentre
    first tremor in ~6 s
    main shaking in ~11 s
  • Carrara
    38 km from the epicentre
    first tremor in ~7 s
    main shaking in ~11 s
  • Pistoia
    45 km from the epicentre
    first tremor in ~8 s
    main shaking in ~13 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

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 (~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: 8 months ago the same area had a stronger quake (M2.6). This can only be said after the fact — it was not predictable beforehand.

2.6
The mainshock
7 km South-West of Vetto
8 months ago · 15 Dec, 10:56
Activity in the area right now (30 km radius)
0
last 24 hours
1
last 7 days
5
last 30 days
7 before3 after
this quake
Strongest of the sequence2.6

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: 1133 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 · 20 km from here
XCompletely destructive: most buildings are destroyed.
15016.0
Modenese earthquake
5 June 1501 · 39 km from here
IXDestructive: many buildings partly or fully collapse.
18375.9
Lunigiana earthquake
11 April 1837 · 28 km from here
XCompletely destructive: most buildings are destroyed.
17405.6
Garfagnana earthquake
6 March 1740 · 23 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

Garfagnana

The epicentre lies about 11 km from Garfagnana, one of the seismic structures mapped by INGV geologists.

estimated maximum magnitude 6.9between 1 and 10 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

1.3
9 months ago
7 Dec, 20:48
1.2
9 months ago
12 Dec, 06:53
0.9
7 km West of Abetone Cutigliano
21 km South-East · 11 km
9 months ago
6 Dec, 10:44
1.3
9 months ago
5 Dec, 01:41
1.4
9 months ago
5 Dec, 01:33
2.6
7 km South-West of Vetto
22 km North-West · 25 km
8 months ago
15 Dec, 10:56
1.8
5 km West of Baiso
25 km North · 25 km
8 months ago
31 Dec, 22:31
1.4
6 km North-East of Montefiorino
16 km North-East · 9 km
9 months ago
15 Nov, 23:19
1.6
10 months ago
13 Nov, 14:13
1.7
10 months ago
12 Nov, 02:29

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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