All earthquakes
3.2
weak
EARTHQUAKE DETAILS

5 km South-West of Trapani

77 months ago · 4 May, 19:14

A weak earthquake, felt by some of the population. At only a few km deep the shaking is felt more sharply at the surface.

Stronger than 98% of Italian events in the past yearThe strongest of the past 12 months within 50 km

Where

5 km South-West of TrapaniEarthquakes 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 ~15 km · felt only by some, at rest
    ≈ 201,000 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

2 events
Magnitude:lightweakmoderatestrong

The energy released

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

952kgof TNT equivalent
4.0 lightning bolts
M3
×2 the energy of a magnitude 3 earthquake
M2this quakeM4

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 ≈ 25 s

Animation sped up ~5× compared to reality.

  • Trapani
    5 km from the epicentre
    first tremor in ~2 s
    main shaking in ~3 s
  • Marsala
    11 km from the epicentre
    first tremor in ~2 s
    main shaking in ~4 s
  • Palermo
    74 km from the epicentre
    first tremor in ~12 s
    main shaking in ~21 s
  • Bagheria
    87 km from the epicentre
    first tremor in ~15 s
    main shaking in ~25 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.

in line with the area average (~11 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
0
last 30 days
0 before1 after
this quake
Strongest of the sequence2.0

How often does it happen here?

about every ~13 months

Within 50 km of this epicentre, a magnitude ≥ 3 earthquake has occurred on average this often: 11 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.

19686.4
Valle del Belice earthquake
15 January 1968 · 47 km from here
XCompletely destructive: most buildings are destroyed.
19415.9
Tirreno meridionale earthquake
16 March 1941 · 47 km from here
19685.5
Valle del Belice earthquake
15 January 1968 · 41 km from here
19685.5
Valle del Belice earthquake
16 January 1968 · 44 km from here
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

Mazara-Belice

The epicentre lies about 29 km from Mazara-Belice, one of the seismic structures mapped by INGV geologists.

estimated maximum magnitude 6.1between 2 and 6 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

2.0
20 km North of Favignana
24 km North-West · 5 km
76 months ago
26 May, 16:26

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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