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2.3
light
EARTHQUAKE DETAILS

M2.3 earthquake · 3 km East of Padula (SA)

9 years ago · 20 May 2017, 09:38

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

Stronger than 93% of Italian events in the past year

Where

3 km East of PadulaEarthquakes 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

26 events
Magnitude:lightweakmoderatestrong

The energy released

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

43kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×11 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 ≈ 25 s

Animation sped up ~5× compared to reality.

  • Potenza
    37 km from the epicentre
    first tremor in ~6 s
    main shaking in ~11 s
  • Battipaglia
    68 km from the epicentre
    first tremor in ~11 s
    main shaking in ~20 s
  • Salerno
    85 km from the epicentre
    first tremor in ~14 s
    main shaking in ~24 s
  • Matera
    88 km from the epicentre
    first tremor in ~15 s
    main shaking in ~25 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 (~16 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?

Mainshock

It is the strongest quake of its sequence: so far it has been followed by 17 aftershocks within 30 km. Aftershocks tend to fade in number and strength over time.

Activity in the area right now (30 km radius)
0
last 24 hours
3
last 7 days
16
last 30 days
8 before17 after
this quake
Strongest of the sequence2.2

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: 361 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 · 29 km from here
X-XICatastrophic: very few buildings remain standing; landslides and ground cracks.
15616.3
Vallo di Diano earthquake
31 July 1561 · 43 km from here
IX-XCompletely destructive: most buildings are destroyed.
19775.9
Golfo di Policastro earthquake
30 December 1977 · 45 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 3 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

1.1
9 years ago
15 May 2017, 20:47
1.1
3 km South of Grumento Nova
19 km East · 10 km
9 years ago
15 May 2017, 15:24
1.3
4 km West of Paterno
4 km North · 8 km
9 years ago
14 May 2017, 06:54
1.1
3 km West of Paterno
4 km North-East · 10 km
9 years ago
28 May 2017, 13:01
1.0
3 km West of Tramutola
5 km East · 7 km
9 years ago
30 May 2017, 21:59
1.8
3 km South-East of Sarconi
25 km South-East · 21 km
9 years ago
31 May 2017, 20:17
0.5
3 km North-East of Sanza
13 km South-West · 16 km
9 years ago
2 Jun 2017, 09:53
0.4
5 km South-West of Casalbuono
19 km South · 10 km
9 years ago
5 May 2017, 09:04
2.2
4 km West of Tramutola
5 km East · 8 km
9 years ago
4 Jun 2017, 13:59
1.2
5 km West of Pignola
28 km North · 21 km
9 years ago
5 Jun 2017, 22:14

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).