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4.7
moderate
EARTHQUAKE DETAILS

Tirreno Meridionale [Mare]

12 months ago · 26 Aug, 06:07

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. 4 of the year in ItalyStronger than 99% of Italian events in the past yearNo. 1 of the year in SiciliaThe strongest of the past 12 months within 50 km

Where

Tirreno Meridionale [Mare]Earthquakes in the province of TrapaniEarthquakes 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?

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

  • up to ~18 km · clearly felt by almost everyone
  • up to ~44 km · felt by many people, especially on upper floors
  • up to ~92 km · felt only by some, at rest
    ≈ 4,000 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.

169tof TNT equivalent
708 lightning bolts
M3
×355 the energy of a magnitude 3 earthquake
M4this quakeM6

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.

  • Erice
    95 km from the epicentre
    first tremor in ~16 s
    main shaking in ~27 s
  • Trapani
    96 km from the epicentre
    first tremor in ~16 s
    main shaking in ~28 s
  • Marsala
    97 km from the epicentre
    first tremor in ~16 s
    main shaking in ~28 s
  • Mazara del Vallo
    120 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
1.1 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 (~17 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

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

How often does it happen here?

It is the first magnitude ≥ 4.5 earthquake recorded within 50 km since 2014, the start of our archive.

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.

19795.3
Stretto di Sicilia earthquake
8 December 1979 · 21 km from here
19994.8
Tirreno meridionale earthquake
30 December 1999 · 34 km from here
IIILight: felt by few people, like a passing truck.
19774.8
Tirreno meridionale earthquake
30 June 1977 · 38 km from here
20004.5
Tirreno meridionale earthquake
7 January 2000 · 31 km from here

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).

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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