All earthquakes
1.7
very light
EARTHQUAKE DETAILS

25 km North of Pollina

62 months ago · 19 Jul, 17:02

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

25 km North of PollinaEarthquakes in the province of PalermoEarthquakes in Sicilia

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

4 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 ≈ 31 s

Animation sped up ~6× compared to reality.

  • Bagheria
    56 km from the epicentre
    first tremor in ~9 s
    main shaking in ~16 s
  • Palermo
    69 km from the epicentre
    first tremor in ~12 s
    main shaking in ~20 s
  • Caltanissetta
    82 km from the epicentre
    first tremor in ~14 s
    main shaking in ~24 s
  • Agrigento
    110 km from the epicentre
    first tremor in ~18 s
    main shaking in ~31 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

6 km
shallow

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

shallower than the area average (~12 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
2
last 7 days
9
last 30 days
2 before1 after
this quake
Strongest of the sequence0.9

How often does it happen here?

about every ~8 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 527 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.

20025.9
Tirreno meridionale earthquake
6 September 2002 · 41 km from here
VIStrong: felt by everyone, many get scared; objects fall, first light damage to buildings.
18235.8
Sicilia settentrionale earthquake
5 March 1823 · 21 km from here
VIII-IXDestructive: many buildings partly or fully collapse.
19805.7
Tirreno meridionale earthquake
28 May 1980 · 33 km from here
VI-VIIVery strong: hard to stand; chimneys and roof tiles fall, serious damage to weaker buildings.
18195.4
Monti Madonie earthquake
24 February 1819 · 31 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

Southern Tyrrhenian S

The epicentre lies about 18 km from Southern Tyrrhenian S, one of the seismic structures mapped by INGV geologists.

estimated maximum magnitude 7.0between 3 and 16 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

0.9
3 km West of Pollina
25 km South · 4 km
62 months ago
24 Jul, 22:49
0.4
63 months ago
27 Jun, 23:08
0.9
3 km South-East of Cefalù
27 km South · 4 km
63 months ago
21 Jun, 10:53

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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