All earthquakes
1.0
very light
EARTHQUAKE DETAILS

1 km South-West of San Chirico Raparo

27 months ago · 31 May, 15:45

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 30% of Italian events in the past year

Where

1 km South-West of San Chirico RaparoEarthquakes in the province of PotenzaEarthquakes in Basilicata

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

35 events
Magnitude:lightweakmoderatestrong

The energy released

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

0.5kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×1,000 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 ≈ 24 s

Animation sped up ~4× compared to reality.

  • Potenza
    56 km from the epicentre
    first tremor in ~9 s
    main shaking in ~16 s
  • Corigliano-Rossano
    72 km from the epicentre
    first tremor in ~12 s
    main shaking in ~21 s
  • Matera
    73 km from the epicentre
    first tremor in ~12 s
    main shaking in ~21 s
  • Altamura
    82 km from the epicentre
    first tremor in ~14 s
    main shaking in ~24 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 (~16 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 (M2.6, 27 months ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

2.6
The mainshock
2 km South of Viggiano
27 months ago · 31 May, 13:58
Activity in the area right now (30 km radius)
1
last 24 hours
1
last 7 days
8
last 30 days
24 before10 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: 291 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.

18577.1
Basilicata earthquake
16 December 1857 · 26 km from here
XICatastrophic: very few buildings remain standing; landslides and ground cracks.
18365.9
Appennino lucano earthquake
20 November 1836 · 26 km from here
IXDestructive: many buildings partly or fully collapse.
18265.7
Potentino earthquake
1 February 1826 · 46 km from here
IXDestructive: many buildings partly or fully collapse.
17085.6
Pollino earthquake
26 January 1708 · 30 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 lies about 14 km from Rimendiello-Mormanno, one of the seismic structures mapped by INGV geologists.

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

2.6
2 km South of Viggiano
20 km North-West · 59 km
27 months ago
31 May, 13:58
2.5
27 months ago
31 May, 13:08
0.8
27 months ago
1 Jun, 03:15
0.9
4 km West of Viggiano
25 km North-West · 9 km
27 months ago
2 Jun, 19:20
0.9
27 months ago
2 Jun, 19:55
1.2
2 km North-East of Spinoso
10 km North-West · 9 km
27 months ago
29 May, 06:28
0.7
5 km East of Spinoso
5 km West · 16 km
27 months ago
26 May, 02:49
1.0
27 months ago
6 Jun, 09:53
2.3
3 km West of Castelsaraceno
12 km West · 8 km
28 months ago
23 May, 22:34
1.7
2 km West of Castelsaraceno
11 km West · 9 km
28 months ago
22 May, 18:09

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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