All earthquakes
1.3
very light
EARTHQUAKE DETAILS

M1.3 earthquake · 6 km South-East of Castrovillari (CS)

9 years ago · 21 Jul 2017, 14:03

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 55% of Italian events in the past year

Where

6 km South-East 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

14 events
Magnitude:lightweakmoderatestrong

The energy released

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

1.3kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×355 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
    22 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
    91 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
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 (~19 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 (M2.6). This can only be said after the fact — it was not predictable beforehand.

2.6
The mainshock
6 km South-East of Cassano all'Ionio
9 years ago · 27 Jul 2017, 18:37
Activity in the area right now (30 km radius)
0
last 24 hours
0
last 7 days
8
last 30 days
9 before4 after
this quake
Strongest of the sequence2.6

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: 283 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 · 43 km from here
IXDestructive: many buildings partly or fully collapse.
18366.2
Calabria settentrionale earthquake
25 April 1836 · 46 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

1.3
5 km East of Mormanno
25 km West · 8 km
9 years ago
19 Jul 2017, 03:21
1.3
9 years ago
19 Jul 2017, 00:16
2.5
9 years ago
17 Jul 2017, 11:57
1.3
6 km East of Mormanno
24 km West · 8 km
9 years ago
15 Jul 2017, 20:41
2.6
6 km South-East of Cassano all'Ionio
15 km South-East · 66 km
9 years ago
27 Jul 2017, 18:37
0.9
1 km North-East of Roggiano Gravina
16 km South-West · 8 km
9 years ago
14 Jul 2017, 10:48
1.5
4 km North of Morano Calabro
20 km North-West · 8 km
9 years ago
11 Jul 2017, 09:07
1.6
9 years ago
1 Aug 2017, 03:05
0.9
6 km North-East of Morano Calabro
19 km North-West · 9 km
9 years ago
10 Jul 2017, 01:29
1.3
4 km South-East of Rotonda
21 km North-West · 8 km
9 years ago
6 Aug 2017, 00:53

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).