All earthquakes
0.9
very light
EARTHQUAKE DETAILS

2 km North of Grumento Nova

138 months ago · 6 May, 19:21

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

Stronger than 23% of Italian events in the past year

Where

2 km North of Grumento NovaEarthquakes 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

36 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
    39 km from the epicentre
    first tremor in ~7 s
    main shaking in ~12 s
  • Matera
    76 km from the epicentre
    first tremor in ~13 s
    main shaking in ~22 s
  • Altamura
    82 km from the epicentre
    first tremor in ~14 s
    main shaking in ~24 s
  • Battipaglia
    84 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

13 km
medium depth
1.4 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 (M2.4, 139 months ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

2.4
The mainshock
3 km North of Castelluccio Superiore
139 months ago · 9 Apr, 11:14
Activity in the area right now (30 km radius)
1
last 24 hours
1
last 7 days
13
last 30 days
16 before19 after
this quake
Strongest of the sequence2.4

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: 320 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 · 6 km from here
XICatastrophic: very few buildings remain standing; landslides and ground cracks.
15616.7
Vallo di Diano earthquake
19 August 1561 · 42 km from here
X-XICatastrophic: very few buildings remain standing; landslides and ground cracks.
18365.9
Appennino lucano earthquake
20 November 1836 · 21 km from here
IXDestructive: many buildings partly or fully collapse.
12735.8
Potenza earthquake
18 December 1273 · 37 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

Irpinia-Agri Valley

The epicentre sits above this source area: the deep structure where this area's earthquakes can originate.

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

0.9
4 km East of Lauria
25 km South · 14 km
138 months ago
5 May, 07:32
1.2
1 km East of Paterno
13 km North-West · 19 km
138 months ago
1 May, 18:00
0.5
138 months ago
1 May, 12:23
1.0
137 months ago
13 May, 08:51
1.1
2 km South-West of Spinoso
11 km South-East · 9 km
137 months ago
14 May, 12:08
1.3
1 km West of Casalbuono
21 km South-West · 11 km
138 months ago
27 Apr, 09:48
0.8
4 km East of Torraca
28 km South-West · 10 km
138 months ago
26 Apr, 22:50
0.9
2 km North-West of Abriola
27 km North · 19 km
138 months ago
26 Apr, 16:53
1.6
3 km North-East of Laurenzana
21 km North-East · 10 km
138 months ago
25 Apr, 17:26
0.3
3 km South-East of Sarconi
13 km South-East · 9 km
137 months ago
19 May, 07:33

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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