All earthquakes
1.7
very light
EARTHQUAKE DETAILS

6 km NW Escalaplano (CA)

39 months ago · 31 May, 10:13

A very light earthquake, probably not felt by people. At only a few km deep the shaking is felt more sharply at the surface.

Stronger than 78% of Italian events in the past year

Where

6 km NW Escalaplano (CA)Earthquakes in the province of CagliariEarthquakes in Sardegna

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?

A quake this small is usually not felt by people: only seismographs record it.

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

7 events
Magnitude:lightweakmoderatestrong

The energy released

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

5.4kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×89 its energy
M1this quakeM3

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 ≈ 41 s

Animation sped up ~8× compared to reality.

  • Quartu Sant'Elena
    51 km from the epicentre
    first tremor in ~9 s
    main shaking in ~15 s
  • Cagliari
    54 km from the epicentre
    first tremor in ~9 s
    main shaking in ~16 s
  • Olbia
    139 km from the epicentre
    first tremor in ~23 s
    main shaking in ~40 s
  • Sassari
    144 km from the epicentre
    first tremor in ~24 s
    main shaking in ~41 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

1 km
shallow

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

in line with the area average (~2 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?

Aftershock

It is an aftershock: it follows a stronger quake (M1.8, 40 months ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

1.8
The mainshock
6 km SE Orroli (CA)
40 months ago · 26 May, 10:03
Activity in the area right now (30 km radius)
0
last 24 hours
0
last 7 days
0
last 30 days
3 before3 after
this quake
Strongest of the sequence1.8

How often does it happen here?

It is the first magnitude ≥ 2 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 closest seismic structure

Northern Africa offshore - East

The epicentre lies about 141 km from Northern Africa offshore - East, one of the seismic structures mapped by INGV geologists.

estimated maximum magnitude 8.0between 1 and 25 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

1.8
6 km SE Orroli (CA)
2 km West · 1 km
40 months ago
26 May, 10:03
1.5
6 km NW Escalaplano (CA)
1 km West · 1 km
39 months ago
7 Jun, 09:56
1.6
5 km N Escalaplano (CA)
1 km South-East · 1 km
40 months ago
22 May, 10:43
1.7
5 km SE Orroli (CA)
2 km West · 1 km
39 months ago
13 Jun, 10:18
1.7
5 km N Escalaplano (CA)
1 km East · 1 km
40 months ago
10 May, 12:12
1.7
6 km NW Escalaplano (CA)
1 km West · 1 km
39 months ago
26 Jun, 10:48

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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