All earthquakes
3.1
weak
EARTHQUAKE DETAILS

M3.1 offshore earthquake

9 years ago · 24 Apr 2017, 01:42

A weak earthquake, felt by some of the population. Being deep, it is felt less at the surface.

Stronger than 98% of Italian events in the past year

Where

Nearest Italian town: Longobardi (CS)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

5 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 ≈ 71 s

Animation sped up ~13× compared to reality.

  • Cosenza
    48 km from the epicentre
    first tremor in ~40 s
    main shaking in ~68 s
  • Lamezia Terme
    56 km from the epicentre
    first tremor in ~40 s
    main shaking in ~68 s
  • Corigliano-Rossano
    76 km from the epicentre
    first tremor in ~41 s
    main shaking in ~70 s
  • Catanzaro
    84 km from the epicentre
    first tremor in ~41 s
    main shaking in ~71 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

232 km
deep
26 times the height of Mount Everest

Being deep, it is felt less at the surface.

deeper than the area average (~98 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 one aftershock 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
0
last 7 days
6
last 30 days
3 before1 after
this quake
Strongest of the sequence2.4

How often does it happen here?

about every ~41 days

Within 50 km of this epicentre, a magnitude ≥ 3 earthquake has occurred on average this often: 105 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 · 45 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.
19945.8
Tirreno meridionale earthquake
5 January 1994 · 47 km from here
IV-VRather strong: felt by almost everyone; hanging objects swing.
18865.6
Cosentino earthquake
6 March 1886 · 43 km from here
VII-VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.

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

The closest seismic structure

Crati Valley

The epicentre lies about 44 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

2.4
Costa Calabra nord-occidentale (Cosenza)
18 km North · 226 km
9 years ago
18 Apr 2017, 15:46
2.4
Costa Calabra nord-occidentale (Cosenza)
24 km North-West · 239 km
9 years ago
12 Apr 2017, 23:50
1.6
8 km South-West of Paola
26 km North-East · 55 km
9 years ago
11 Apr 2017, 09:40
1.7
9 years ago
20 May 2017, 01:21

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).