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3.1
weak
EARTHQUAKE DETAILS

M3.1 earthquake · 3 km North-West of Luzzi (CS)

9 years ago · 5 Apr 2017, 21:17

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

Stronger than 98% of Italian events in the past year

Where

3 km North-West of LuzziEarthquakes in the province of CosenzaEarthquakes in Calabria

How far away could it be felt?

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

  • up to ~13 km · felt only by some, at rest
    ≈ 55,000 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

19 events
Magnitude:lightweakmoderatestrong

The energy released

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

674kgof TNT equivalent
2.8 lightning bolts
M3
×1.4 the energy of a magnitude 3 earthquake
M2this quakeM4

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 ≈ 20 s

Animation sped up ~4× compared to reality.

  • Cosenza
    20 km from the epicentre
    first tremor in ~4 s
    main shaking in ~6 s
  • Corigliano-Rossano
    23 km from the epicentre
    first tremor in ~4 s
    main shaking in ~7 s
  • Lamezia Terme
    56 km from the epicentre
    first tremor in ~9 s
    main shaking in ~16 s
  • Catanzaro
    69 km from the epicentre
    first tremor in ~12 s
    main shaking in ~20 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

9 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 (~20 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 11 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
5
last 7 days
18
last 30 days
7 before11 after
this quake
Strongest of the sequence2.5

How often does it happen here?

about every ~3 months

Within 50 km of this epicentre, a magnitude ≥ 3 earthquake has occurred on average this often: 52 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 · 46 km from here
XICatastrophic: very few buildings remain standing; landslides and ground cracks.
11846.8
Valle del Crati earthquake
24 May 1184 · 10 km from here
IXDestructive: many buildings partly or fully collapse.
18546.3
Cosentino earthquake
12 February 1854 · 23 km from here
XCompletely destructive: most buildings are destroyed.
18706.2
Cosentino earthquake
4 October 1870 · 27 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

1.4
1 km East of Celico
17 km South-East · 18 km
9 years ago
2 Apr 2017, 14:45
1.5
9 years ago
9 Apr 2017, 04:36
1.6
8 km South-West of Paola
28 km South-West · 55 km
9 years ago
11 Apr 2017, 09:40
1.1
9 years ago
12 Apr 2017, 17:36
1.3
7 km North of Celico
12 km East · 14 km
9 years ago
16 Apr 2017, 04:56
1.6
3 km North of Terranova da Sibari
27 km North-East · 10 km
9 years ago
24 Mar 2017, 11:23
1.4
3 km South-East of Torano Castello
7 km North-West · 7 km
9 years ago
20 Apr 2017, 18:38
1.6
9 years ago
20 Apr 2017, 23:53
1.8
9 years ago
20 Mar 2017, 19:45
1.2
9 years ago
19 Mar 2017, 23:26

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).