All earthquakes
1.8
very light
EARTHQUAKE DETAILS

M1.8 earthquake · 6 km East of Mormanno (CS)

9 years ago · 26 Feb 2017, 18:59

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 82% of Italian events in the past year

Where

6 km East of MormannoEarthquakes in the province of CosenzaEarthquakes 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

14 events
Magnitude:lightweakmoderatestrong

The energy released

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

7.6kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×63 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 ≈ 30 s

Animation sped up ~6× compared to reality.

  • Corigliano-Rossano
    45 km from the epicentre
    first tremor in ~8 s
    main shaking in ~13 s
  • Cosenza
    69 km from the epicentre
    first tremor in ~12 s
    main shaking in ~20 s
  • Potenza
    90 km from the epicentre
    first tremor in ~15 s
    main shaking in ~26 s
  • Lamezia Terme
    103 km from the epicentre
    first tremor in ~17 s
    main shaking in ~30 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

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?

Foreshock

In hindsight it was a foreshock: 9 years ago the same area had a stronger quake (M3.4). This can only be said after the fact — it was not predictable beforehand.

3.4
The mainshock
4 km West of Orsomarso
9 years ago · 11 Mar 2017, 13:35
Activity in the area right now (30 km radius)
0
last 24 hours
1
last 7 days
12
last 30 days
6 before7 after
this quake
Strongest of the sequence3.4

How often does it happen here?

about every ~12 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 355 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.

19775.9
Golfo di Policastro earthquake
30 December 1977 · 50 km from here
18365.9
Appennino lucano earthquake
20 November 1836 · 37 km from here
IXDestructive: many buildings partly or fully collapse.
19135.6
Calabria settentrionale earthquake
28 June 1913 · 42 km from here
VIII-IXDestructive: many buildings partly or fully collapse.
17085.6
Pollino earthquake
26 January 1708 · 11 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

Rimendiello-Mormanno

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

estimated maximum magnitude 6.6between 1 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

1.8
9 years ago
2 Mar 2017, 01:39
2.1
5 km East of Morano Calabro
14 km East · 11 km
9 years ago
23 Feb 2017, 11:29
0.9
7 km South of Lauria
20 km North-West · 10 km
9 years ago
3 Mar 2017, 22:33
1.5
4 km North of Castrovillari
18 km East · 9 km
9 years ago
21 Feb 2017, 08:06
0.5
9 years ago
16 Feb 2017, 20:11
1.7
2 km North-West of Scalea
20 km West · 48 km
9 years ago
10 Mar 2017, 15:17
3.4
4 km West of Orsomarso
14 km South-West · 277 km
9 years ago
11 Mar 2017, 13:35
1.5
9 years ago
11 Mar 2017, 16:27
1.3
5 km North-East of Lauria
28 km North · 13 km
9 years ago
19 Mar 2017, 04:42
1.7
1 km North-West of Viggianello
16 km North-East · 17 km
9 years ago
3 Feb 2017, 21:08

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).