All earthquakes
1.8
very light
EARTHQUAKE DETAILS

6 km East of Trecchina

47 months ago · 12 Oct, 06:20

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 82% of Italian events in the past year

Where

6 km East of TrecchinaEarthquakes 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

10 events
Magnitude:lightweakmoderatestrong

The energy released

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

7.6kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×63 its energy
M1this quakeM3

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 ≈ 28 s

Animation sped up ~5× compared to reality.

  • Corigliano-Rossano
    68 km from the epicentre
    first tremor in ~12 s
    main shaking in ~20 s
  • Potenza
    70 km from the epicentre
    first tremor in ~12 s
    main shaking in ~20 s
  • Cosenza
    92 km from the epicentre
    first tremor in ~15 s
    main shaking in ~26 s
  • Battipaglia
    98 km from the epicentre
    first tremor in ~16 s
    main shaking in ~28 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

8 km
shallow

At only a few km deep the shaking is felt more sharply at the surface.

shallower than the area average (~19 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: 47 months ago the same area had a stronger quake (M5.4). This can only be said after the fact — it was not predictable beforehand.

5.4
The mainshock
9 km West of San Nicola Arcella
47 months ago · 31 Oct, 22:42
Activity in the area right now (30 km radius)
0
last 24 hours
1
last 7 days
14
last 30 days
3 before6 after
this quake
Strongest of the sequence5.4

How often does it happen here?

about every ~12 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 347 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 · 36 km from here
XICatastrophic: very few buildings remain standing; landslides and ground cracks.
19775.9
Golfo di Policastro earthquake
30 December 1977 · 34 km from here
18365.9
Appennino lucano earthquake
20 November 1836 · 14 km from here
IXDestructive: many buildings partly or fully collapse.
17085.6
Pollino earthquake
26 January 1708 · 25 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 5 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

1.3
4 km South of Sarconi
19 km North-East · 61 km
47 months ago
9 Oct, 13:27
2.1
48 months ago
30 Sept, 07:17
1.3
16 km South-West of Maratea
28 km South-West · 9 km
47 months ago
24 Oct, 11:02
1.4
2 km South-West of San Martino d'Agri
29 km North-East · 10 km
48 months ago
26 Sept, 13:56
5.4
9 km West of San Nicola Arcella
22 km South-West · 287 km
47 months ago
31 Oct, 22:42
1.3
5 km North-East of Nemoli
10 km North · 9 km
46 months ago
1 Nov, 21:48
1.7
3 km West of Rotonda
18 km South-East · 9 km
46 months ago
4 Nov, 00:02
2.6
5 km West of Praia a Mare
19 km South-West · 20 km
46 months ago
9 Nov, 12:08
1.2
18 km South-West of Maratea
29 km South-West · 8 km
46 months ago
10 Nov, 00:57

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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