All earthquakes
2.1
light
EARTHQUAKE DETAILS

9 km North-East of Pollina

23 days ago · 2 Aug, 10:10

A light earthquake, rarely felt by people. At only a few km deep the shaking is felt more sharply at the surface.

Stronger than 90% of Italian events in the past year

Where

9 km North-East 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

33 events
Magnitude:lightweakmoderatestrong

The energy released

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

21kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×22 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 ≈ 28 s

Animation sped up ~5× compared to reality.

  • Bagheria
    60 km from the epicentre
    first tremor in ~10 s
    main shaking in ~17 s
  • Caltanissetta
    66 km from the epicentre
    first tremor in ~11 s
    main shaking in ~19 s
  • Palermo
    75 km from the epicentre
    first tremor in ~13 s
    main shaking in ~21 s
  • Agrigento
    98 km from the epicentre
    first tremor in ~16 s
    main shaking in ~28 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

7 km
shallow

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

shallower than the area average (~15 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 (M2.3, 23 days ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

2.3
The mainshock
11 km North-East of Pollina
23 days ago · 2 Aug, 09:41
Activity in the area right now (30 km radius)
1
last 24 hours
1
last 7 days
13
last 30 days
23 before9 after
nowthis quake
Strongest of the sequence2.3

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: 564 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.

18235.8
Sicilia settentrionale earthquake
5 March 1823 · 20 km from here
VIII-IXDestructive: many buildings partly or fully collapse.
19805.7
Tirreno meridionale earthquake
28 May 1980 · 48 km from here
VI-VIIVery strong: hard to stand; chimneys and roof tiles fall, serious damage to weaker buildings.
17395.4
Monti Nebrodi earthquake
10 May 1739 · 50 km from here
VIII-IXDestructive: many buildings partly or fully collapse.
18195.4
Monti Madonie earthquake
24 February 1819 · 18 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 36 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

2.3
11 km North-East of Pollina
2 km North · 5 km
23 days ago
2 Aug, 09:41
1.5
10 km North-West of Tusa
2 km North-East · 5 km
24 days ago
1 Aug, 14:11
1.0
21 days ago
4 Aug, 07:59
1.3
25 days ago
31 Jul, 02:03
0.8
12 km North-East of Pollina
3 km North · 6 km
16 days ago
9 Aug, 19:24
1.2
4 km East of Castelbuono
15 km South · 8 km
14 days ago
11 Aug, 11:06
1.9
6 km East of Castelbuono
13 km South · 7 km
13 days ago
12 Aug, 07:50
1.5
13 days ago
12 Aug, 19:41
1.5
5 km East of Castelbuono
15 km South · 6 km
12 days ago
13 Aug, 15:02
1.6
8 km North-West of Tusa
1 km South · 9 km
11 days ago
14 Aug, 03:25

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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