All earthquakes
1.2
very light
EARTHQUAKE DETAILS

M1.2 earthquake · 3 km North-West of Atena Lucana (SA)

9 years ago · 14 Aug 2017, 13:08

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 48% of Italian events in the past year

Where

3 km North-West of Atena LucanaEarthquakes 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

35 events
Magnitude:lightweakmoderatestrong

The energy released

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

1.0kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×501 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 ≈ 21 s

Animation sped up ~4× compared to reality.

  • Potenza
    31 km from the epicentre
    first tremor in ~5 s
    main shaking in ~9 s
  • Battipaglia
    50 km from the epicentre
    first tremor in ~8 s
    main shaking in ~14 s
  • Salerno
    66 km from the epicentre
    first tremor in ~11 s
    main shaking in ~19 s
  • Cava de' Tirreni
    74 km from the epicentre
    first tremor in ~12 s
    main shaking in ~21 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 (~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 (M2.1, 9 years ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

2.1
The mainshock
2 km South of Ricigliano
9 years ago · 6 Aug 2017, 18:23
Activity in the area right now (30 km radius)
0
last 24 hours
2
last 7 days
12
last 30 days
25 before9 after
this quake
Strongest of the sequence2.1

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: 353 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 · 30 km from here
XICatastrophic: very few buildings remain standing; landslides and ground cracks.
19806.8
Irpinia-Basilicata earthquake
23 November 1980 · 45 km from here
XCompletely destructive: most buildings are destroyed.
16946.7
Irpinia-Basilicata earthquake
8 September 1694 · 44 km from here
XCompletely destructive: most buildings are destroyed.
15616.7
Vallo di Diano earthquake
19 August 1561 · 10 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 4 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

1.7
4 km East of Pignola
28 km East · 22 km
9 years ago
13 Aug 2017, 18:41
1.4
3 km South-West of Balvano
18 km North · 9 km
9 years ago
16 Aug 2017, 05:17
0.8
3 km East of Paterno
25 km South-East · 10 km
9 years ago
12 Aug 2017, 03:00
1.0
3 km South-East of Piaggine
21 km South-West · 10 km
9 years ago
17 Aug 2017, 06:52
0.7
3 km North of Campora
26 km South-West · 9 km
9 years ago
19 Aug 2017, 04:58
1.5
2 km South-East of Sanza
27 km South · 10 km
9 years ago
9 Aug 2017, 15:53
0.4
3 km North-East of Campora
25 km South-West · 10 km
9 years ago
9 Aug 2017, 10:26
0.9
1 km South of Satriano di Lucania
10 km North-East · 21 km
9 years ago
9 Aug 2017, 08:57
1.1
3 km South of Sanza
28 km South · 11 km
9 years ago
9 Aug 2017, 07:36
1.4
3 km South-East of Sanza
27 km South · 11 km
9 years ago
9 Aug 2017, 03:35

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).