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3.4
weak
EARTHQUAKE DETAILS

3 km East of Bella

120 months ago · 20 Oct, 02:09

A weak earthquake, felt by some of the population. At this depth the shaking is felt, but rarely causes damage.

Stronger than 99% of Italian events in the past yearNo. 1 of the year in Basilicata

Where

3 km East of BellaEarthquakes in the province of PotenzaEarthquakes in Basilicata

How far away could it be felt?

An estimate of how far people may have felt this quake.

  • up to ~15 km · felt only by some, at rest
    ≈ 41,000 people live in this area

The coloured rings on the map below show these distances.

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

21 events
Magnitude:lightweakmoderatestrong

The energy released

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

1.9tof TNT equivalent
7.9 lightning bolts
M3
×4 the energy of a magnitude 3 earthquake
M2this quakeM4

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 ≈ 20 s

Animation sped up ~4× compared to reality.

  • Potenza
    17 km from the epicentre
    first tremor in ~4 s
    main shaking in ~7 s
  • Cerignola
    58 km from the epicentre
    first tremor in ~10 s
    main shaking in ~17 s
  • Battipaglia
    60 km from the epicentre
    first tremor in ~11 s
    main shaking in ~18 s
  • Andria
    67 km from the epicentre
    first tremor in ~12 s
    main shaking in ~20 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

17 km
medium depth
1.9 times the height of Mount Everest

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

in line with the area average (~15 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?

Mainshock

It is the strongest quake of its sequence: so far it has been followed by 11 aftershocks within 30 km. Aftershocks tend to fade in number and strength over time.

Activity in the area right now (30 km radius)
0
last 24 hours
2
last 7 days
15
last 30 days
9 before11 after
this quake
Strongest of the sequence2.5

How often does it happen here?

about every ~4 months

Within 50 km of this epicentre, a magnitude ≥ 3 earthquake has occurred on average this often: 36 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 · 48 km from here
XICatastrophic: very few buildings remain standing; landslides and ground cracks.
19806.8
Irpinia-Basilicata earthquake
23 November 1980 · 32 km from here
XCompletely destructive: most buildings are destroyed.
16946.7
Irpinia-Basilicata earthquake
8 September 1694 · 23 km from here
XCompletely destructive: most buildings are destroyed.
15616.7
Vallo di Diano earthquake
19 August 1561 · 24 km from here
X-XICatastrophic: very few buildings remain standing; landslides and ground cracks.

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

The closest seismic structure

Andretta-Filano

The epicentre lies about 3 km from Andretta-Filano, one of the seismic structures mapped by INGV geologists.

estimated maximum magnitude 7.0between 2 and 15 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

1.3
6 km North-East of Bella
3 km North-East · 20 km
120 months ago
20 Oct, 03:03
1.2
2 km South-West of Vietri di Potenza
21 km South-West · 8 km
120 months ago
22 Oct, 10:04
1.3
2 km West of Pignola
22 km South-East · 21 km
120 months ago
23 Oct, 18:55
1.4
5 km East of Balvano
14 km South-West · 6 km
120 months ago
10 Oct, 20:37
1.6
5 km West of Potenza
15 km South-East · 17 km
120 months ago
6 Oct, 14:31
2.1
3 km East of Romagnano al Monte
20 km South-West · 5 km
120 months ago
5 Oct, 23:06
1.3
4 km West of Muro Lucano
19 km West · 14 km
121 months ago
30 Sept, 12:52
1.1
3 km East of Ricigliano
17 km South-West · 14 km
121 months ago
28 Sept, 22:38
1.2
2 km South-East of Baragiano
9 km South · 10 km
121 months ago
28 Sept, 22:33
1.7
121 months ago
28 Sept, 16:28

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).

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