All earthquakes
1.1
very light
EARTHQUAKE DETAILS

5 km West of Montemurro

48 months ago · 6 Sept, 05:07

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 39% of Italian events in the past year

Where

5 km West of MontemurroEarthquakes 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

9 events
Magnitude:lightweakmoderatestrong

The energy released

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

0.7kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×708 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
    40 km from the epicentre
    first tremor in ~7 s
    main shaking in ~12 s
  • Matera
    72 km from the epicentre
    first tremor in ~12 s
    main shaking in ~21 s
  • Altamura
    78 km from the epicentre
    first tremor in ~13 s
    main shaking in ~23 s
  • Corigliano-Rossano
    88 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

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?

Foreshock

In hindsight it was a foreshock: 48 months ago the same area had a stronger quake (M1.4). This can only be said after the fact — it was not predictable beforehand.

1.4
The mainshock
2 km South-West of San Martino d'Agri
48 months ago · 26 Sept, 13:56
Activity in the area right now (30 km radius)
1
last 24 hours
1
last 7 days
11
last 30 days
3 before5 after
this quake
Strongest of the sequence1.4

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: 312 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 · 9 km from here
XICatastrophic: very few buildings remain standing; landslides and ground cracks.
15616.7
Vallo di Diano earthquake
19 August 1561 · 46 km from here
X-XICatastrophic: very few buildings remain standing; landslides and ground cracks.
18365.9
Appennino lucano earthquake
20 November 1836 · 24 km from here
IXDestructive: many buildings partly or fully collapse.
12735.8
Potenza earthquake
18 December 1273 · 38 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 lies about 4 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

1.1
2 km West of Pietrapertosa
23 km North-East · 20 km
48 months ago
9 Sept, 04:39
1.3
3 km West of Pietrapertosa
23 km North-East · 19 km
48 months ago
9 Sept, 06:01
1.1
4 km South-West of Montemurro
5 km South-East · 17 km
49 months ago
26 Aug, 23:56
0.9
1 km North of Abriola
28 km North-West · 22 km
49 months ago
22 Aug, 22:25
1.2
5 km North of Calvello
22 km North-West · 19 km
48 months ago
26 Sept, 08:17
1.4
2 km South-West of San Martino d'Agri
13 km South-East · 10 km
48 months ago
26 Sept, 13:56
1.4
4 km South-East of Abriola
23 km North-West · 13 km
48 months ago
29 Sept, 22:08
0.6
49 months ago
9 Aug, 00:22

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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