All earthquakes
0.9
very light
EARTHQUAKE DETAILS

4 km South-West of San Chirico Raparo

123 months ago · 31 Jul, 02:16

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 23% of Italian events in the past year

Where

4 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

26 events
Magnitude:lightweakmoderatestrong

The energy released

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

0.3kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×1,413 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 ~5× 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
    75 km from the epicentre
    first tremor in ~13 s
    main shaking in ~22 s
  • Altamura
    85 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

9 km
shallow

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 (M2.0, 124 months ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

2.0
The mainshock
6 km South-West of Sant'Arcangelo
124 months ago · 5 Jul, 01:37
Activity in the area right now (30 km radius)
1
last 24 hours
1
last 7 days
8
last 30 days
12 before13 after
this quake
Strongest of the sequence2.0

How often does it happen here?

about every ~14 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 295 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 · 24 km from here
XICatastrophic: very few buildings remain standing; landslides and ground cracks.
18365.9
Appennino lucano earthquake
20 November 1836 · 23 km from here
IXDestructive: many buildings partly or fully collapse.
18265.7
Potentino earthquake
1 February 1826 · 45 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 11 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

0.9
3 km South-East of Marsicovetere
25 km North-West · 10 km
123 months ago
1 Aug, 02:25
1.4
5 km North-West of Grumento Nova
22 km North-West · 9 km
123 months ago
29 Jul, 22:25
0.7
4 km West of Castelsaraceno
9 km West · 12 km
123 months ago
2 Aug, 11:19
1.7
6 km West of Stigliano
26 km North-East · 22 km
123 months ago
27 Jul, 00:44
1.4
4 km East of Marsicovetere
25 km North-West · 5 km
123 months ago
26 Jul, 07:37
1.7
3 km North-West of Rivello
30 km West · 10 km
122 months ago
5 Aug, 04:44
1.1
122 months ago
8 Aug, 00:28
1.5
1 km South-East of Marsicovetere
27 km North-West · 9 km
122 months ago
9 Aug, 08:33
1.1
5 km North-West of Grumento Nova
22 km North-West · 13 km
123 months ago
20 Jul, 12:22
0.9
4 km South-East of Sarconi
8 km West · 12 km
123 months ago
18 Jul, 15:38

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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