All earthquakes
1.1
very light
EARTHQUAKE DETAILS

6 km South-West of Bisignano

58 months ago · 27 Nov, 19:35

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 39% of Italian events in the past year

Where

6 km South-West of BisignanoEarthquakes in the province of CosenzaEarthquakes in Calabria

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

17 events
Magnitude:lightweakmoderatestrong

The energy released

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

0.7kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×708 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 ≈ 21 s

Animation sped up ~4× compared to reality.

  • Corigliano-Rossano
    22 km from the epicentre
    first tremor in ~4 s
    main shaking in ~7 s
  • Cosenza
    23 km from the epicentre
    first tremor in ~4 s
    main shaking in ~7 s
  • Lamezia Terme
    59 km from the epicentre
    first tremor in ~10 s
    main shaking in ~17 s
  • Catanzaro
    73 km from the epicentre
    first tremor in ~12 s
    main shaking in ~21 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

4 km
shallow

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

shallower than the area average (~21 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: 58 months ago the same area had a stronger quake (M2.0). This can only be said after the fact — it was not predictable beforehand.

2.0
The mainshock
7 km West of Fuscaldo
58 months ago · 6 Dec, 05:00
Activity in the area right now (30 km radius)
0
last 24 hours
2
last 7 days
13
last 30 days
10 before6 after
this quake
Strongest of the sequence2.0

How often does it happen here?

about every ~10 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 435 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.

16387.1
Calabria centrale earthquake
27 March 1638 · 49 km from here
XICatastrophic: very few buildings remain standing; landslides and ground cracks.
11846.8
Valle del Crati earthquake
24 May 1184 · 11 km from here
IXDestructive: many buildings partly or fully collapse.
18546.3
Cosentino earthquake
12 February 1854 · 26 km from here
XCompletely destructive: most buildings are destroyed.
18706.2
Cosentino earthquake
4 October 1870 · 30 km from here
XCompletely destructive: most buildings are destroyed.

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

The closest seismic structure

Crati Valley

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

estimated maximum magnitude 6.6between 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

1.2
6 km South-West of Acri
13 km East · 11 km
58 months ago
24 Nov, 17:22
1.3
2 km East of San Benedetto Ullano
11 km South-West · 8 km
58 months ago
1 Dec, 19:02
1.2
2 km East of Cerisano
23 km South · 11 km
58 months ago
22 Nov, 03:04
2.0
7 km West of Fuscaldo
26 km West · 54 km
58 months ago
6 Dec, 05:00
1.2
4 km East of Luzzi
8 km East · 12 km
58 months ago
17 Nov, 02:14
2.0
3 km West of Rota Greca
16 km West · 27 km
57 months ago
10 Dec, 05:08
0.3
2 km West of Zumpano
19 km South · 8 km
58 months ago
12 Nov, 23:12
1.1
5 km North-East of Pietrafitta
24 km South-East · 13 km
58 months ago
11 Nov, 07:57
2.0
3 km South of Castrolibero
22 km South · 56 km
57 months ago
15 Dec, 04:41
1.2
58 months ago
10 Nov, 02:00

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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