All earthquakes
1.1
very light
EARTHQUAKE DETAILS

3 km North-West of Montesano sulla Marcellana

1 month ago · 22 Jul, 07:58

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

3 km North-West of Montesano sulla MarcellanaEarthquakes in the province of SalernoEarthquakes in Campania

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

29 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 ≈ 26 s

Animation sped up ~5× compared to reality.

  • Potenza
    42 km from the epicentre
    first tremor in ~7 s
    main shaking in ~12 s
  • Battipaglia
    72 km from the epicentre
    first tremor in ~12 s
    main shaking in ~21 s
  • Salerno
    89 km from the epicentre
    first tremor in ~15 s
    main shaking in ~25 s
  • Matera
    89 km from the epicentre
    first tremor in ~15 s
    main shaking in ~26 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 (~17 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: 22 days ago the same area had a stronger quake (M3.2). This can only be said after the fact — it was not predictable beforehand.

3.2
The mainshock
4 km East of Cannalonga
22 days ago · 3 Aug, 20:11
Activity in the area right now (30 km radius)
0
last 24 hours
2
last 7 days
17
last 30 days
6 before22 after
this quake
Strongest of the sequence3.2

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: 345 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 · 13 km from here
XICatastrophic: very few buildings remain standing; landslides and ground cracks.
15616.7
Vallo di Diano earthquake
19 August 1561 · 35 km from here
X-XICatastrophic: very few buildings remain standing; landslides and ground cracks.
15616.3
Vallo di Diano earthquake
31 July 1561 · 48 km from here
IX-XCompletely destructive: most buildings are destroyed.
19775.9
Golfo di Policastro earthquake
30 December 1977 · 41 km from here

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

The closest seismic structure

Irpinia-Agri Valley

The epicentre lies about 5 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

1.6
5 km East of Caselle in Pittari
15 km South-West · 12 km
1 month ago
23 Jul, 06:07
1.8
3 km East of Tramutola
9 km East · 36 km
1 month ago
24 Jul, 08:09
2.0
1 km West of Paterno
9 km North · 9 km
1 month ago
25 Jul, 12:24
1.3
1 km West of Paterno
9 km North · 9 km
1 month ago
25 Jul, 12:36
1.2
1 km West of Paterno
9 km North · 10 km
1 month ago
25 Jul, 12:40
1.3
1 month ago
18 Jul, 05:12
0.8
1 month ago
17 Jul, 19:01
0.7
2 km West of Roccagloriosa
29 km South-West · 9 km
1 month ago
17 Jul, 07:52
1.0
0 km North of Abriola
28 km North · 10 km
26 days ago
29 Jul, 21:31
1.1
2 km North-West of Sala Consilina
16 km North-West · 18 km
26 days ago
30 Jul, 06:49

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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