All earthquakes
1.7
very light
EARTHQUAKE DETAILS

M1.7 earthquake · 1 km East of Acquaformosa (CS)

3 years ago · 18 May 2023, 01:32

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 78% of Italian events in the past year

Where

1 km East of AcquaformosaEarthquakes 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

20 events
Magnitude:lightweakmoderatestrong

The energy released

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

5.4kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×89 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 ≈ 29 s

Animation sped up ~5× compared to reality.

  • Corigliano-Rossano
    31 km from the epicentre
    first tremor in ~5 s
    main shaking in ~9 s
  • Cosenza
    52 km from the epicentre
    first tremor in ~9 s
    main shaking in ~15 s
  • Lamezia Terme
    87 km from the epicentre
    first tremor in ~15 s
    main shaking in ~25 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

8 km
shallow

At only a few km deep the shaking is felt more sharply at the surface.

shallower than the area average (~25 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 (M1.8, 3 years ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

1.8
The mainshock
4 km South of Bisignano
3 years ago · 14 May 2023, 10:51
Activity in the area right now (30 km radius)
0
last 24 hours
0
last 7 days
10
last 30 days
1 before18 after
this quake
Strongest of the sequence1.8

How often does it happen here?

about every ~13 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 343 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 · 38 km from here
IXDestructive: many buildings partly or fully collapse.
18355.9
Cosentino earthquake
12 October 1835 · 47 km from here
XCompletely destructive: most buildings are destroyed.
17675.9
Valle del Crati earthquake
14 July 1767 · 42 km from here
VIII-IXDestructive: many buildings partly or fully collapse.
19135.6
Calabria settentrionale earthquake
28 June 1913 · 25 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 lies about 11 km from Pollino, one of the seismic structures mapped by INGV geologists.

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

1.5
5 km East of Grisolia
12 km West · 9 km
3 years ago
21 May 2023, 13:48
1.8
4 km South of Bisignano
30 km South-East · 8 km
3 years ago
14 May 2023, 10:51
1.2
2 km North-West of Castrovillari
17 km North-East · 5 km
3 years ago
22 May 2023, 18:46
1.2
1 km South-East of Castrovillari
16 km North-East · 9 km
3 years ago
26 May 2023, 04:42
0.9
1 km South-East of Mottafollone
11 km South-West · 30 km
3 years ago
27 May 2023, 10:02
0.9
2 km North-West of Cerzeto
22 km South · 10 km
3 years ago
6 Jun 2023, 03:02
0.9
4 km South-East of Rotonda
21 km North · 9 km
3 years ago
7 Jun 2023, 06:49
1.6
4 km South-East of Rotonda
21 km North · 8 km
3 years ago
7 Jun 2023, 06:57
1.4
5 km North of Morano Calabro
20 km North · 9 km
3 years ago
7 Jun 2023, 10:17
1.2
1 km South of Morano Calabro
14 km North · 10 km
3 years ago
14 Jun 2023, 04:28

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).