All earthquakes
1.9
very light
EARTHQUAKE DETAILS

Costa Calabra nord-occidentale (Cosenza)

24 months ago · 22 Sept, 15:05

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

Costa Calabra nord-occidentale (Cosenza)Earthquakes in the province of CosenzaEarthquakes in Calabria

Epicentre at sea

The epicentre is at sea: for the same magnitude, the shaking is felt less on land, because the energy fades along the way before reaching the coast.

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.

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 ≈ 26 s

Animation sped up ~5× compared to reality.

  • Cosenza
    48 km from the epicentre
    first tremor in ~8 s
    main shaking in ~14 s
  • Lamezia Terme
    65 km from the epicentre
    first tremor in ~11 s
    main shaking in ~19 s
  • Corigliano-Rossano
    68 km from the epicentre
    first tremor in ~11 s
    main shaking in ~20 s
  • Catanzaro
    91 km from the epicentre
    first tremor in ~15 s
    main shaking in ~26 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
medium depth
1.1 times the height of Mount Everest

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

shallower than the area average (~79 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: 24 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
Tirreno Meridionale [Mare]
24 months ago · 22 Sept, 21:24
Activity in the area right now (30 km radius)
0
last 24 hours
0
last 7 days
2
last 30 days
1 before9 after
this quake
Strongest of the sequence2.6

How often does it happen here?

about every ~7 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 635 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.

11846.8
Valle del Crati earthquake
24 May 1184 · 40 km from here
IXDestructive: many buildings partly or fully collapse.
18546.3
Cosentino earthquake
12 February 1854 · 50 km from here
XCompletely destructive: most buildings are destroyed.
18355.9
Cosentino earthquake
12 October 1835 · 48 km from here
XCompletely destructive: most buildings are destroyed.
17675.9
Valle del Crati earthquake
14 July 1767 · 47 km from here
VIII-IXDestructive: many buildings partly or fully collapse.

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

The closest seismic structure

Crati Valley

The epicentre lies about 42 km from Crati Valley, one of the seismic structures mapped by INGV geologists.

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

2.6
Tirreno Meridionale [Mare]
28 km South-West · 268 km
24 months ago
22 Sept, 21:24
1.9
11 km West of Longobardi
26 km South-East · 42 km
23 months ago
30 Sept, 03:30
2.3
23 months ago
1 Oct, 01:49
1.6
Tirreno Meridionale [Mare]
27 km North-West · 82 km
24 months ago
12 Sept, 01:07
1.9
12 km West of Paola
16 km East · 65 km
23 months ago
4 Oct, 16:11
1.8
11 km West of Longobardi
30 km South-East · 54 km
23 months ago
8 Oct, 03:57
1.7
3 km West of Paola
26 km East · 47 km
23 months ago
13 Oct, 07:32
1.8
12 km West of Longobardi
23 km South-East · 31 km
23 months ago
14 Oct, 00:41
2.3
10 km West of Longobardi
26 km South-East · 47 km
23 months ago
19 Oct, 13:43
2.6
Tirreno Meridionale [Mare]
24 km West · 228 km
23 months ago
20 Oct, 11:00

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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