All earthquakes
1.2
very light
EARTHQUAKE DETAILS

M1.2 earthquake · 6 km South of Castrovillari (CS)

9 years ago · 28 Aug 2017, 20:51

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 48% of Italian events in the past year

Where

6 km South of CastrovillariEarthquakes 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

18 events
Magnitude:lightweakmoderatestrong

The energy released

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

1.0kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×501 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 ≈ 29 s

Animation sped up ~5× compared to reality.

  • Corigliano-Rossano
    24 km from the epicentre
    first tremor in ~4 s
    main shaking in ~7 s
  • Cosenza
    55 km from the epicentre
    first tremor in ~9 s
    main shaking in ~16 s
  • Lamezia Terme
    90 km from the epicentre
    first tremor in ~15 s
    main shaking in ~26 s
  • Catanzaro
    102 km from the epicentre
    first tremor in ~17 s
    main shaking in ~29 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 (~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?

Foreshock

In hindsight it was a foreshock: 9 years ago the same area had a stronger quake (M2.2). This can only be said after the fact — it was not predictable beforehand.

2.2
The mainshock
7 km South of Castrovillari
9 years ago · 1 Sept 2017, 14:48
Activity in the area right now (30 km radius)
0
last 24 hours
0
last 7 days
8
last 30 days
3 before14 after
this quake
Strongest of the sequence2.2

How often does it happen here?

about every ~15 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 287 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 · 42 km from here
IXDestructive: many buildings partly or fully collapse.
18366.2
Calabria settentrionale earthquake
25 April 1836 · 48 km from here
XCompletely destructive: most buildings are destroyed.
18355.9
Cosentino earthquake
12 October 1835 · 49 km from here
XCompletely destructive: most buildings are destroyed.
17675.9
Valle del Crati earthquake
14 July 1767 · 44 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

Pollino

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

estimated maximum magnitude 6.4between 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

0.6
9 years ago
28 Aug 2017, 22:01
2.2
7 km South of Castrovillari
1 km South-East · 4 km
9 years ago
1 Sept 2017, 14:48
1.1
5 km East of Rotonda
20 km North-West · 9 km
9 years ago
7 Sept 2017, 20:06
1.4
3 km South-East of Morano Calabro
12 km North-West · 11 km
9 years ago
17 Aug 2017, 05:57
1.9
3 km North-West of Fagnano Castello
28 km South-West · 38 km
9 years ago
9 Sept 2017, 11:50
1.8
5 km South-East of Castrovillari
3 km North-East · 8 km
9 years ago
16 Sept 2017, 12:02
1.3
4 km South-East of Rotonda
20 km North-West · 8 km
9 years ago
6 Aug 2017, 00:53
1.4
9 years ago
23 Sept 2017, 02:36
1.6
5 km South-East of Castrovillari
3 km North-East · 8 km
9 years ago
23 Sept 2017, 18:58
1.8
2 km North of Morano Calabro
16 km North-West · 9 km
9 years ago
24 Sept 2017, 15:41

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).