All earthquakes
1.1
very light
EARTHQUAKE DETAILS

3 km South-West of Anzi

37 months ago · 25 Aug, 02:13

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

Stronger than 39% of Italian events in the past year

Where

3 km South-West of AnziEarthquakes 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

47 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 ≈ 23 s

Animation sped up ~4× compared to reality.

  • Potenza
    18 km from the epicentre
    first tremor in ~4 s
    main shaking in ~7 s
  • Matera
    65 km from the epicentre
    first tremor in ~11 s
    main shaking in ~19 s
  • Altamura
    67 km from the epicentre
    first tremor in ~12 s
    main shaking in ~20 s
  • Andria
    78 km from the epicentre
    first tremor in ~13 s
    main shaking in ~23 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

18 km
medium depth
2 times the height of Mount Everest

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

in line with the area average (~14 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 (M1.9, 37 months ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

1.9
The mainshock
4 km North-East of Brienza
37 months ago · 22 Aug, 08:46
Activity in the area right now (30 km radius)
2
last 24 hours
5
last 7 days
23
last 30 days
30 before16 after
this quake
Strongest of the sequence1.9

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: 343 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 · 17 km from here
XICatastrophic: very few buildings remain standing; landslides and ground cracks.
15616.7
Vallo di Diano earthquake
19 August 1561 · 33 km from here
X-XICatastrophic: very few buildings remain standing; landslides and ground cracks.
15616.3
Vallo di Diano earthquake
31 July 1561 · 45 km from here
IX-XCompletely destructive: most buildings are destroyed.
18365.9
Appennino lucano earthquake
20 November 1836 · 41 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 14 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

0.7
3 km South-West of Anzi
1 km North · 19 km
37 months ago
25 Aug, 02:18
1.1
5 km West of Anzi
3 km North-West · 20 km
37 months ago
25 Aug, 02:01
1.1
3 km South-West of Anzi
1 km North-West · 18 km
37 months ago
25 Aug, 01:58
0.5
4 km East of Abriola
4 km North-West · 21 km
37 months ago
25 Aug, 02:36
1.4
4 km South-West of Anzi
1 km South-East · 20 km
37 months ago
25 Aug, 02:40
1.1
4 km South-West of Anzi
1 km South-East · 20 km
37 months ago
25 Aug, 02:49
1.2
3 km South-West of Anzi
1 km South-East · 17 km
37 months ago
25 Aug, 03:14
0.8
4 km West of Anzi
2 km North-West · 20 km
37 months ago
25 Aug, 05:34
0.6
37 months ago
25 Aug, 10:58
1.5
4 km North-East of Moliterno
28 km South · 10 km
37 months ago
25 Aug, 17:48

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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