All earthquakes
1.2
very light
EARTHQUAKE DETAILS

2 km South-East of Spinoso

50 months ago · 11 Jul, 13:36

A very light earthquake, probably not felt by people. At this depth the shaking is felt, but rarely causes damage.

Stronger than 47% of Italian events in the past year

Where

2 km South-East of SpinosoEarthquakes 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

19 events
Magnitude:lightweakmoderatestrong

The energy released

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

1.0kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×501 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 ≈ 25 s

Animation sped up ~5× compared to reality.

  • Potenza
    50 km from the epicentre
    first tremor in ~9 s
    main shaking in ~15 s
  • Matera
    76 km from the epicentre
    first tremor in ~13 s
    main shaking in ~23 s
  • Corigliano-Rossano
    78 km from the epicentre
    first tremor in ~13 s
    main shaking in ~23 s
  • Altamura
    84 km from the epicentre
    first tremor in ~15 s
    main shaking in ~25 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

20 km
medium depth
2.3 times the height of Mount Everest

At this depth the shaking is felt, but rarely causes damage.

in line with 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 (M1.7, 50 months ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

1.7
The mainshock
5 km North-West of Viggianello
50 months ago · 5 Jul, 07:12
Activity in the area right now (30 km radius)
1
last 24 hours
1
last 7 days
8
last 30 days
11 before7 after
this quake
Strongest of the sequence1.7

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: 318 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 · 18 km from here
XICatastrophic: very few buildings remain standing; landslides and ground cracks.
18365.9
Appennino lucano earthquake
20 November 1836 · 19 km from here
IXDestructive: many buildings partly or fully collapse.
12735.8
Potenza earthquake
18 December 1273 · 48 km from here
VIII-IXDestructive: many buildings partly or fully collapse.
18265.7
Potentino earthquake
1 February 1826 · 39 km from here
IXDestructive: many buildings partly or fully collapse.

Source: Parametric Catalogue of Italian Earthquakes CPTI15 (INGV, CC BY 4.0).

The closest seismic structure

Irpinia-Agri Valley

The epicentre lies about 7 km from Irpinia-Agri Valley, one of the seismic structures mapped by INGV geologists.

estimated maximum magnitude 6.8between 1 and 14 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

1.0
50 months ago
11 Jul, 21:41
0.5
5 km North-East of Nemoli
16 km South-West · 14 km
50 months ago
10 Jul, 23:37
0.7
4 km South-East of Sarconi
3 km South-West · 7 km
50 months ago
8 Jul, 01:25
1.7
5 km North-West of Viggianello
25 km South-East · 8 km
50 months ago
5 Jul, 07:12
1.0
1 km East of Episcopia
21 km South-East · 21 km
50 months ago
18 Jul, 19:00
0.9
2 km South-East of Marsicovetere
19 km North-West · 9 km
50 months ago
19 Jul, 00:12
1.1
51 months ago
3 Jul, 23:06
0.3
6 km East of Lagonegro
13 km South-West · 8 km
50 months ago
20 Jul, 03:44
0.8
1 km West of Rivello
26 km South-West · 10 km
51 months ago
30 Jun, 22:01
1.5
2 km North of Fardella
25 km South-East · 24 km
50 months ago
22 Jul, 18:01

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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