All earthquakes
4.1
moderate
EARTHQUAKE DETAILS

Tunisia [Sea]

6 days ago · 18 Aug, 20:21

A moderate earthquake, felt by people in the area. At this depth the shaking is felt, but rarely causes damage.

No. 3 of the month in ItalyStronger than 99% of Italian events in the past year

Where

Tunisia [Sea]Earthquakes in the province of AgrigentoEarthquakes 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 ~17 km · felt by many people, especially on upper floors
  • up to ~48 km · felt only by some, at rest

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.

How deep it was born

15 km
medium depth
1.7 times the height of Mount Everest

At this depth the shaking is felt, but rarely causes damage.

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
1
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?

It is the first magnitude ≥ 4 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.

19935.3
Stretto di Sicilia earthquake
10 September 1993 · 24 km from here

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

The closest seismic structure

LampedusaN

The epicentre lies about 53 km from LampedusaN, one of the seismic structures mapped by INGV geologists.

estimated maximum magnitude 7.6between 3 and 13 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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