All earthquakes
3.9
weak
EARTHQUAKE DETAILS

7 km East of Strongoli

84 months ago · 15 Oct, 13:54

A weak earthquake, felt by some of the population. At only a few km deep the shaking is felt more sharply at the surface.

No. 4 of the month in ItalyStronger than 99% of Italian events in the past yearThe strongest of the past 12 months within 50 km

Where

7 km East of StrongoliEarthquakes in the province of CrotoneEarthquakes in Calabria

How far away could it be felt?

An estimate of how far people may have felt this quake.

  • up to ~15 km · felt by many people, especially on upper floors
    ≈ 78,000 people live in this area
  • up to ~39 km · felt only by some, at rest
    ≈ 191,000 people live in this area

The coloured rings on the map below show these distances.

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

9 events
Magnitude:lightweakmoderatestrong

The energy released

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

11tof TNT equivalent
45 lightning bolts
M3
×22 the energy of a magnitude 3 earthquake
M3this quakeM5

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 ≈ 22 s

Animation sped up ~4× compared to reality.

  • Crotone
    13 km from the epicentre
    first tremor in ~3 s
    main shaking in ~5 s
  • Catanzaro
    59 km from the epicentre
    first tremor in ~10 s
    main shaking in ~17 s
  • Cosenza
    76 km from the epicentre
    first tremor in ~13 s
    main shaking in ~22 s
  • Corigliano-Rossano
    76 km from the epicentre
    first tremor in ~13 s
    main shaking in ~22 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 (~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?

Mainshock

It is the strongest quake of its sequence: so far it has been followed by 4 aftershocks within 30 km. Aftershocks tend to fade in number and strength over time.

Activity in the area right now (30 km radius)
0
last 24 hours
1
last 7 days
3
last 30 days
4 before4 after
this quake
Strongest of the sequence2.7

How often does it happen here?

about every ~6 months

Within 50 km of this epicentre, a magnitude ≥ 3.5 earthquake has occurred on average this often: 24 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.

16386.8
Crotonese earthquake
8 June 1638 · 30 km from here
XCompletely destructive: most buildings are destroyed.
18326.7
Crotonese earthquake
8 March 1832 · 25 km from here
XCompletely destructive: most buildings are destroyed.
17445.7
Sila Piccola earthquake
21 March 1744 · 37 km from here
IXDestructive: many buildings partly or fully collapse.
19325.5
Ionio settentrionale earthquake
2 January 1932 · 39 km from here
VIStrong: felt by everyone, many get scared; objects fall, first light damage to buildings.

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

The closest seismic structure

Crotone-Rossano

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

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

2.7
84 months ago
18 Oct, 00:03
2.1
9 km East of Strongoli
3 km East · 10 km
84 months ago
10 Oct, 08:07
2.5
6 km East of Cirò Marina
18 km North · 10 km
83 months ago
21 Oct, 20:07
1.8
7 km East of Strongoli
2 km North · 10 km
83 months ago
23 Oct, 22:09
2.4
3 km South of Strongoli
6 km West · 10 km
83 months ago
24 Oct, 07:19
0.6
10 km East of Cirò Marina
15 km North-East · 10 km
84 months ago
30 Sept, 01:15
2.3
7 km East of Cirò Marina
20 km North · 11 km
84 months ago
29 Sept, 21:50
2.6
10 km East of Cirò Marina
21 km North · 11 km
84 months ago
29 Sept, 18:54

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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