All earthquakes
4.1
moderate
EARTHQUAKE DETAILS

14 km North-West of Favignana

18 months ago · 15 Mar, 21:45

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

No. 20 of the year in ItalyStronger than 99% of Italian events in the past yearNo. 5 of the year in Sicilia

Where

14 km North-West of FavignanaEarthquakes in the province of TrapaniEarthquakes in Sicilia

How far away could it be felt?

An estimate of how far people may have felt this quake.

  • up to ~1 km · clearly felt by almost everyone
  • up to ~21 km · felt by many people, especially on upper floors
    ≈ 4,000 people live in this area
  • up to ~49 km · felt only by some, at rest
    ≈ 226,000 people live in this area

The coloured rings on the map below show these distances.

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

1 events
Magnitude:lightweakmoderatestrong

The energy released

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

21tof TNT equivalent
89 lightning bolts
M3
×45 the energy of a magnitude 3 earthquake
M3this quakeM5

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 ≈ 32 s

Animation sped up ~6× compared to reality.

  • Trapani
    31 km from the epicentre
    first tremor in ~5 s
    main shaking in ~9 s
  • Marsala
    32 km from the epicentre
    first tremor in ~5 s
    main shaking in ~9 s
  • Palermo
    97 km from the epicentre
    first tremor in ~16 s
    main shaking in ~28 s
  • Bagheria
    112 km from the epicentre
    first tremor in ~19 s
    main shaking in ~32 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

6 km
shallow

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

shallower than the area average (~13 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
0
last 7 days
1
last 30 days

No other quakes within 30 km in the 30 days around the event.

How often does it happen here?

about every ~3.9 years

Within 50 km of this epicentre, a magnitude ≥ 4 earthquake has occurred on average this often: 3 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.

19415.9
Tirreno meridionale earthquake
16 March 1941 · 26 km from here
19795.3
Stretto di Sicilia earthquake
8 December 1979 · 48 km from here
18285.1
Sicilia occidentale earthquake
18 May 1828 · 36 km from here
VIIVery strong: hard to stand; chimneys and roof tiles fall, serious damage to weaker buildings.
19814.9
Mazara del Vallo earthquake
7 June 1981 · 49 km from here
VIStrong: felt by everyone, many get scared; objects fall, first light damage to buildings.

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

The closest seismic structure

Southern Tyrrhenian

The epicentre lies about 22 km from Southern Tyrrhenian, one of the seismic structures mapped by INGV geologists.

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).

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).

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