All earthquakes
1.6
very light
EARTHQUAKE DETAILS

M1.6 offshore earthquake

6 years ago · 21 Feb 2020, 02:14

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 74% of Italian events in the past year

Where

Nearest Italian town: Leni (ME)Earthquakes in the province of MessinaEarthquakes in Sicilia

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

27 events
Magnitude:lightweakmoderatestrong

The energy released

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

3.8kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×126 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 ≈ 34 s

Animation sped up ~6× compared to reality.

  • Messina
    97 km from the epicentre
    first tremor in ~16 s
    main shaking in ~28 s
  • Bagheria
    110 km from the epicentre
    first tremor in ~18 s
    main shaking in ~32 s
  • Reggio di Calabria
    117 km from the epicentre
    first tremor in ~20 s
    main shaking in ~34 s
  • Palermo
    119 km from the epicentre
    first tremor in ~20 s
    main shaking in ~34 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 (~41 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?

Foreshock

In hindsight it was a foreshock: 6 years ago the same area had a stronger quake (M3.1). This can only be said after the fact — it was not predictable beforehand.

3.1
The mainshock
23 km West of Leni
6 years ago · 29 Feb 2020, 10:18
Activity in the area right now (30 km radius)
0
last 24 hours
3
last 7 days
14
last 30 days
1 before25 after
this quake
Strongest of the sequence3.1

How often does it happen here?

about every ~5 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 827 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.

19805.7
Tirreno meridionale earthquake
28 May 1980 · 28 km from here
VI-VIIVery strong: hard to stand; chimneys and roof tiles fall, serious damage to weaker buildings.
20045.4
Isole Eolie earthquake
5 May 2004 · 23 km from here
IVModerate: felt by many indoors; glasses and dishes rattle.
19575.3
Tirreno meridionale earthquake
21 May 1957 · 35 km from here
IV-VRather strong: felt by almost everyone; hanging objects swing.
19265.3
Isole Eolie earthquake
17 August 1926 · 26 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

Southern Tyrrhenian

The epicentre sits above this source area: the deep structure where this area's earthquakes can originate.

estimated maximum magnitude 8.2between 2 and 18 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

2.3
5 km South-West of Leni
22 km East · 19 km
6 years ago
24 Feb 2020, 06:04
2.2
Isole Eolie (Messina)
10 km West · 9 km
6 years ago
25 Feb 2020, 07:23
2.2
22 km West of Leni
12 km South · 14 km
6 years ago
26 Feb 2020, 07:11
1.8
24 km West of Leni
14 km South · 10 km
6 years ago
26 Feb 2020, 07:58
1.6
25 km West of Leni
18 km South · 5 km
6 years ago
26 Feb 2020, 08:43
2.9
23 km West of Leni
8 km South · 20 km
6 years ago
29 Feb 2020, 09:30
1.9
22 km West of Leni
11 km South · 14 km
6 years ago
29 Feb 2020, 09:48
2.3
22 km West of Leni
10 km South · 15 km
6 years ago
29 Feb 2020, 10:00
1.9
22 km West of Leni
11 km South · 15 km
6 years ago
29 Feb 2020, 10:08
3.1
23 km West of Leni
7 km South · 20 km
6 years ago
29 Feb 2020, 10:18

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).