All earthquakes
0.9
very light
EARTHQUAKE DETAILS

M0.9 earthquake · 3 km South-West of Cutro (KR)

5 years ago · 25 Jul 2021, 12:49

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 23% of Italian events in the past year

Where

3 km South-West of CutroEarthquakes in the province of CrotoneEarthquakes 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.

0.3kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×1,413 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 ≈ 19 s

Animation sped up ~4× compared to reality.

  • Crotone
    19 km from the epicentre
    first tremor in ~3 s
    main shaking in ~6 s
  • Catanzaro
    32 km from the epicentre
    first tremor in ~6 s
    main shaking in ~9 s
  • Lamezia Terme
    58 km from the epicentre
    first tremor in ~10 s
    main shaking in ~17 s
  • Cosenza
    67 km from the epicentre
    first tremor in ~11 s
    main shaking in ~19 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

8 km
shallow

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

shallower than the area average (~18 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: 5 years 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 East of Crotone
5 years ago · 15 Aug 2021, 15:17
Activity in the area right now (30 km radius)
0
last 24 hours
0
last 7 days
1
last 30 days
6 before10 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: 611 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.

17837.0
Calabria centrale earthquake
28 March 1783 · 47 km from here
XICatastrophic: very few buildings remain standing; landslides and ground cracks.
16386.8
Crotonese earthquake
8 June 1638 · 36 km from here
XCompletely destructive: most buildings are destroyed.
18326.7
Crotonese earthquake
8 March 1832 · 12 km from here
XCompletely destructive: most buildings are destroyed.
16266.1
Calabria centrale earthquake
4 April 1626 · 45 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

Crotone-Rossano

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

estimated maximum magnitude 7.3between 3 and 12 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

0.9
5 km South-East of Rocca di Neto
22 km North-East · 22 km
5 years ago
28 Jul 2021, 22:24
1.5
4 km North of Crotone
21 km North-East · 20 km
5 years ago
29 Jul 2021, 00:16
1.6
3 km West of Cutro
4 km North · 10 km
5 years ago
20 Jul 2021, 21:30
1.1
2 km South-West of Cutro
1 km North-East · 7 km
5 years ago
31 Jul 2021, 04:02
2.1
3 km South of Crotone
16 km North-East · 7 km
5 years ago
17 Jul 2021, 03:35
1.5
3 km North-East of Sellia
26 km West · 34 km
5 years ago
6 Jul 2021, 20:07
2.6
7 km East of Crotone
24 km North-East · 18 km
5 years ago
15 Aug 2021, 15:17
2.4
7 km East of Crotone
24 km North-East · 19 km
5 years ago
15 Aug 2021, 15:23
1.0
3 km West of Crotone
17 km North-East · 16 km
5 years ago
15 Aug 2021, 15:39
1.4
5 km East of Scandale
21 km North-East · 22 km
5 years ago
15 Aug 2021, 22:49

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).