All earthquakes
1.7
very light
EARTHQUAKE DETAILS

M1.7 offshore earthquake

9 years ago · 16 Feb 2017, 21:18

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 78% of Italian events in the past year

Where

Nearest Italian town: Ricadi (VV)Earthquakes in the province of Vibo ValentiaEarthquakes in Calabria

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

18 events
Magnitude:lightweakmoderatestrong

The energy released

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

5.4kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×89 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 ≈ 27 s

Animation sped up ~5× compared to reality.

  • Messina
    56 km from the epicentre
    first tremor in ~9 s
    main shaking in ~16 s
  • Reggio di Calabria
    69 km from the epicentre
    first tremor in ~12 s
    main shaking in ~20 s
  • Lamezia Terme
    77 km from the epicentre
    first tremor in ~13 s
    main shaking in ~22 s
  • Cosenza
    95 km from the epicentre
    first tremor in ~16 s
    main shaking in ~27 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

At only a few km deep the shaking is felt more sharply at the surface.

shallower than the area average (~112 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 (M2.8, 9 years ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

2.8
The mainshock
25 km North of Villafranca Tirrena
9 years ago · 8 Feb 2017, 02:52
Activity in the area right now (30 km radius)
2
last 24 hours
4
last 7 days
14
last 30 days
7 before10 after
this quake
Strongest of the sequence2.8

How often does it happen here?

about every ~3 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 1705 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.

19057.0
Calabria centrale earthquake
8 September 1905 · 48 km from here
X-XICatastrophic: very few buildings remain standing; landslides and ground cracks.
19786.0
Golfo di Patti earthquake
15 April 1978 · 48 km from here
VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
19285.9
Calabria centro-meridionale earthquake
7 March 1928 · 41 km from here
VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
20065.8
Tirreno meridionale earthquake
26 October 2006 · 10 km from here

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

The closest seismic structure

Bagnara-Bovalino

The epicentre lies about 37 km from Bagnara-Bovalino, one of the seismic structures mapped by INGV geologists.

estimated maximum magnitude 7.1between 3 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

2.7
Tirreno Meridionale [Mare]
19 km South-West · 187 km
9 years ago
17 Feb 2017, 00:40
2.5
Isole Eolie (Messina)
15 km South-West · 216 km
9 years ago
15 Feb 2017, 11:33
2.4
Tirreno Meridionale [Mare]
7 km South-West · 218 km
9 years ago
20 Feb 2017, 11:44
2.8
9 years ago
8 Feb 2017, 02:52
2.5
22 km West of Ricadi
15 km South-East · 86 km
9 years ago
5 Feb 2017, 10:02
2.3
Tirreno Meridionale [Mare]
13 km South-West · 5 km
9 years ago
2 Mar 2017, 19:56
1.9
22 km North-West of Tropea
25 km North-East · 101 km
9 years ago
2 Mar 2017, 23:05
2.1
Tirreno Meridionale [Mare]
12 km South-East · 170 km
9 years ago
2 Mar 2017, 23:20
2.0
Tirreno Meridionale [Mare]
23 km North-East · 178 km
9 years ago
4 Mar 2017, 01:47
2.2
Tirreno Meridionale [Mare]
24 km South · 133 km
9 years ago
4 Mar 2017, 16:42

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).