All earthquakes
4.6
moderate
EARTHQUAKE DETAILS

Mar Ionio Settentrionale [Mare]

30 months ago · 22 Mar, 06:20

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

No. 7 of the year in ItalyStronger than 99% of Italian events in the past yearNo. 1 of the year in Puglia

Where

Mar Ionio Settentrionale [Mare]Earthquakes in the province of LecceEarthquakes in Puglia

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 ~15 km · clearly felt by almost everyone
  • up to ~39 km · felt by many people, especially on upper floors
  • up to ~84 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

4 events
Magnitude:lightweakmoderatestrong

The energy released

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

120tof TNT equivalent
501 lightning bolts
M3
×251 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 ≈ 39 s

Animation sped up ~7× compared to reality.

  • Casarano
    111 km from the epicentre
    first tremor in ~19 s
    main shaking in ~32 s
  • Galatina
    122 km from the epicentre
    first tremor in ~21 s
    main shaking in ~35 s
  • Gallipoli
    126 km from the epicentre
    first tremor in ~21 s
    main shaking in ~36 s
  • Lecce
    135 km from the epicentre
    first tremor in ~23 s
    main shaking in ~39 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

10 km
medium depth
1.1 times the height of Mount Everest

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

in line with the area average (~10 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?

Mainshock

It is the strongest quake of its sequence: so far it has been followed by one aftershock within 30 km. Aftershocks tend to fade in number and strength over time.

Activity in the area right now (30 km radius)
0
last 24 hours
0
last 7 days
0
last 30 days
2 before1 after
this quake
Strongest of the sequence3.8

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.

19745.0
Ionio settentrionale earthquake
20 October 1974 · 42 km from here
IVModerate: felt by many indoors; glasses and dishes rattle.
19744.8
Ionio settentrionale earthquake
23 November 1974 · 38 km from here
19764.7
Ionio settentrionale earthquake
22 October 1976 · 38 km from here
19764.6
Ionio settentrionale earthquake
27 October 1976 · 42 km from here

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

The closest seismic structure

Kerkyra offshore

The epicentre lies about 3 km from Kerkyra offshore, one of the seismic structures mapped by INGV geologists.

estimated maximum magnitude 8.0between 3 and 20 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

3.7
30 months ago
20 Mar, 06:19
3.7
30 months ago
20 Mar, 03:46
3.8
29 months ago
26 Mar, 10:00

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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