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EARTHQUAKE DETAILS

1 km West of Valva

122 months ago · 15 Aug, 21:51

A light earthquake, rarely felt by people. At only a few km deep the shaking is felt more sharply at the surface.

Stronger than 88% of Italian events in the past year

Where

1 km West of ValvaEarthquakes 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

15 events
Magnitude:lightweakmoderatestrong

The energy released

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

15kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×32 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 ≈ 14 s

Animation sped up ~3× compared to reality.

  • Battipaglia
    30 km from the epicentre
    first tremor in ~5 s
    main shaking in ~9 s
  • Salerno
    39 km from the epicentre
    first tremor in ~7 s
    main shaking in ~12 s
  • Avellino
    43 km from the epicentre
    first tremor in ~7 s
    main shaking in ~12 s
  • Cava de' Tirreni
    47 km from the epicentre
    first tremor in ~8 s
    main shaking in ~14 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

9 km
shallow
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 (~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?

Aftershock

It is an aftershock: it follows a stronger quake (M2.3, 123 months ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

2.3
The mainshock
2 km North-East of Romagnano al Monte
123 months ago · 1 Aug, 05:34
Activity in the area right now (30 km radius)
0
last 24 hours
1
last 7 days
5
last 30 days
6 before8 after
this quake
Strongest of the sequence2.3

How often does it happen here?

about every ~11 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 372 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.

19806.8
Irpinia-Basilicata earthquake
23 November 1980 · 10 km from here
XCompletely destructive: most buildings are destroyed.
17326.8
Irpinia earthquake
29 November 1732 · 38 km from here
X-XICatastrophic: very few buildings remain standing; landslides and ground cracks.
16946.7
Irpinia-Basilicata earthquake
8 September 1694 · 18 km from here
XCompletely destructive: most buildings are destroyed.
15616.7
Vallo di Diano earthquake
19 August 1561 · 30 km from here
X-XICatastrophic: very few buildings remain standing; landslides and ground cracks.

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

The closest seismic structure

Irpinia-Agri Valley

The epicentre lies about 2 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

1.5
4 km West of Muro Lucano
14 km East · 9 km
122 months ago
13 Aug, 11:35
1.3
3 km East of Rocca San Felice
24 km North · 11 km
122 months ago
5 Aug, 00:36
1.6
4 km West of Muro Lucano
15 km East · 10 km
122 months ago
27 Aug, 20:38
2.3
2 km North-East of Romagnano al Monte
21 km South-East · 10 km
123 months ago
1 Aug, 05:34
1.3
2 km South-East of Lioni
12 km North-West · 12 km
123 months ago
26 Jul, 21:31
1.3
3 km East of Castelgrande
19 km East · 10 km
121 months ago
5 Sept, 17:29
1.2
3 km South of Paternopoli
28 km North-West · 10 km
121 months ago
5 Sept, 22:55
1.6
2 km North-West of Castelfranci
27 km North-West · 16 km
121 months ago
5 Sept, 22:55
1.6
3 km North-East of Montemarano
28 km North-West · 10 km
121 months ago
5 Sept, 23:41
1.5
2 km East of Castelvetere sul Calore
29 km North-West · 9 km
121 months ago
6 Sept, 19:40

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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