All earthquakes
1.9
very light
EARTHQUAKE DETAILS

M1.9 offshore earthquake

8 years ago · 30 Dec 2017, 18:46

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 85% of Italian events in the past year

Where

Nearest Italian town: Camerota (SA)Earthquakes in the province of SalernoEarthquakes in Campania

Epicentre at sea

The epicentre is at sea: for the same magnitude, the shaking is felt less on land, because the energy fades along the way before reaching the coast.

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

2 events
Magnitude:lightweakmoderatestrong

The energy released

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

11kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×45 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 ≈ 33 s

Animation sped up ~6× compared to reality.

  • Cosenza
    92 km from the epicentre
    first tremor in ~15 s
    main shaking in ~26 s
  • Corigliano-Rossano
    94 km from the epicentre
    first tremor in ~16 s
    main shaking in ~27 s
  • Battipaglia
    107 km from the epicentre
    first tremor in ~18 s
    main shaking in ~31 s
  • Lamezia Terme
    114 km from the epicentre
    first tremor in ~19 s
    main shaking in ~33 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 (~75 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?

Isolated quake

In the 30 days around this event no other quakes were recorded within 30 km: a one-off episode, very common in Italy.

Activity in the area right now (30 km radius)
0
last 24 hours
1
last 7 days
1
last 30 days
1 before0 after
this quake
Strongest of the sequence1.2

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: 373 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.

19775.9
Golfo di Policastro earthquake
30 December 1977 · 34 km from here
19985.4
Tirreno meridionale earthquake
18 May 1998 · 48 km from here
19905.3
Tirreno meridionale earthquake
14 December 1990 · 37 km from here
19825.2
Golfo di Policastro earthquake
21 March 1982 · 38 km from here
VII-VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.

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

The closest seismic structure

Rimendiello-Mormanno

The epicentre lies about 60 km from Rimendiello-Mormanno, one of the seismic structures mapped by INGV geologists.

estimated maximum magnitude 6.6between 1 and 12 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

1.2
Golfo di Policastro (Salerno, Potenza)
11 km North · 10 km
8 years ago
6 Dec 2017, 23:16

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).