All earthquakes
1.1
very light
EARTHQUAKE DETAILS

3 km East of Roggiano Gravina

13 months ago · 12 Aug, 21:28

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 39% of Italian events in the past year

Where

3 km East of Roggiano GravinaEarthquakes 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

11 events
Magnitude:lightweakmoderatestrong

The energy released

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

0.7kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×708 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 ≈ 26 s

Animation sped up ~5× compared to reality.

  • Corigliano-Rossano
    20 km from the epicentre
    first tremor in ~4 s
    main shaking in ~6 s
  • Cosenza
    41 km from the epicentre
    first tremor in ~7 s
    main shaking in ~12 s
  • Lamezia Terme
    76 km from the epicentre
    first tremor in ~13 s
    main shaking in ~22 s
  • Catanzaro
    90 km from the epicentre
    first tremor in ~15 s
    main shaking in ~26 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

10 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 (~22 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?

Aftershock

It is an aftershock: it follows a stronger quake (M1.5, 14 months ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

1.5
The mainshock
1 km South-East of Spezzano Albanese
14 months ago · 14 Jul, 08:12
Activity in the area right now (30 km radius)
2
last 24 hours
4
last 7 days
13
last 30 days
4 before6 after
this quake
Strongest of the sequence1.5

How often does it happen here?

about every ~11 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 372 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 · 27 km from here
IXDestructive: many buildings partly or fully collapse.
18546.3
Cosentino earthquake
12 February 1854 · 43 km from here
XCompletely destructive: most buildings are destroyed.
18706.2
Cosentino earthquake
4 October 1870 · 48 km from here
XCompletely destructive: most buildings are destroyed.
18366.2
Calabria settentrionale earthquake
25 April 1836 · 46 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 lies about 4 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

0.9
7 km West of Morano Calabro
29 km North-West · 11 km
13 months ago
11 Aug, 06:47
1.4
7 km East of Bisignano
17 km South-East · 11 km
13 months ago
16 Aug, 16:50
0.7
13 months ago
16 Aug, 20:40
0.7
6 km South-West of Acri
24 km South-East · 13 km
13 months ago
4 Aug, 02:08
0.9
4 km West of Tarsia
2 km South-East · 10 km
12 months ago
3 Sept, 12:19
1.1
3 km East of Tarsia
8 km East · 10 km
12 months ago
4 Sept, 06:43
1.2
1 km North-West of Cetraro
24 km West · 32 km
12 months ago
8 Sept, 01:59
0.6
3 km West of Acri
23 km South-East · 10 km
12 months ago
10 Sept, 01:53
1.2
7 km West of Acri
19 km South-East · 12 km
14 months ago
14 Jul, 12:50
1.5
14 months ago
14 Jul, 08:12

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).

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