All earthquakes
1.0
very light
EARTHQUAKE DETAILS

3 km South-West of Alberona

41 months ago · 17 Apr, 16:00

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

Stronger than 30% of Italian events in the past year

Where

3 km South-West of AlberonaEarthquakes in the province of FoggiaEarthquakes in Puglia

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

17 events
Magnitude:lightweakmoderatestrong

The energy released

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

0.5kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×1,000 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 ≈ 18 s

Animation sped up ~3× compared to reality.

  • San Severo
    36 km from the epicentre
    first tremor in ~7 s
    main shaking in ~11 s
  • Foggia
    40 km from the epicentre
    first tremor in ~7 s
    main shaking in ~12 s
  • Benevento
    42 km from the epicentre
    first tremor in ~8 s
    main shaking in ~13 s
  • Manfredonia
    59 km from the epicentre
    first tremor in ~10 s
    main shaking in ~18 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
2 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?

Foreshock

In hindsight it was a foreshock: 41 months ago the same area had a stronger quake (M1.5). This can only be said after the fact — it was not predictable beforehand.

1.5
The mainshock
1 km South-West of Castelpagano
41 months ago · 21 Apr, 12:46
Activity in the area right now (30 km radius)
0
last 24 hours
0
last 7 days
7
last 30 days
0 before16 after
this quake
Strongest of the sequence1.5

How often does it happen here?

about every ~9 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 460 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.

14567.2
Appennino centro-meridionale earthquake
5 December 1456 · 38 km from here
XICatastrophic: very few buildings remain standing; landslides and ground cracks.
17326.8
Irpinia earthquake
29 November 1732 · 40 km from here
X-XICatastrophic: very few buildings remain standing; landslides and ground cracks.
19306.7
Irpinia earthquake
23 July 1930 · 42 km from here
XCompletely destructive: most buildings are destroyed.
16276.7
Capitanata earthquake
30 July 1627 · 40 km from here
XCompletely destructive: most buildings are destroyed.

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

The closest seismic structure

Pago Veiano-Montaguto

The epicentre lies about 18 km from Pago Veiano-Montaguto, one of the seismic structures mapped by INGV geologists.

estimated maximum magnitude 6.8between 11 and 25 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

1.0
3 km North of Tufara
19 km North-West · 25 km
41 months ago
19 Apr, 02:15
1.3
1 km West of Castelpagano
28 km West · 14 km
41 months ago
19 Apr, 18:40
0.7
1 km West of Castelpagano
28 km West · 20 km
41 months ago
21 Apr, 03:07
1.5
41 months ago
21 Apr, 12:46
1.3
3 km West of Castelpagano
29 km West · 18 km
41 months ago
21 Apr, 23:00
0.8
2 km South of Castelpagano
27 km West · 11 km
41 months ago
22 Apr, 06:31
1.0
4 km East of Tufara
15 km North-West · 22 km
41 months ago
28 Apr, 05:16
0.9
2 km South of Castelpagano
27 km West · 20 km
41 months ago
28 Apr, 21:07
1.4
2 km North-East of Pago Veiano
28 km South-West · 24 km
41 months ago
29 Apr, 23:50
1.2
41 months ago
30 Apr, 03:28

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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