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3.3
weak
EARTHQUAKE DETAILS

5 km North-West of Agira

94 months ago · 30 Sept, 08:23

A weak earthquake, felt by some of the population. Being deep, it is felt less at the surface.

Stronger than 99% of Italian events in the past year

Where

5 km North-West of AgiraEarthquakes in the province of EnnaEarthquakes 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

9 events
Magnitude:lightweakmoderatestrong

The energy released

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

1.3tof TNT equivalent
5.6 lightning bolts
M3
×2.8 the energy of a magnitude 3 earthquake
M2this quakeM4

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 ≈ 21 s

Animation sped up ~4× compared to reality.

  • Caltanissetta
    47 km from the epicentre
    first tremor in ~10 s
    main shaking in ~17 s
  • Catania
    51 km from the epicentre
    first tremor in ~11 s
    main shaking in ~18 s
  • Acireale
    59 km from the epicentre
    first tremor in ~12 s
    main shaking in ~20 s
  • Gela
    62 km from the epicentre
    first tremor in ~12 s
    main shaking in ~21 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

36 km
deep
4.1 times the height of Mount Everest

Being deep, it is felt less at the surface.

deeper 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?

Mainshock

It is the strongest quake of its sequence: so far it has been followed by 4 aftershocks 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
8
last 30 days
4 before4 after
this quake
Strongest of the sequence3.3

How often does it happen here?

about every ~27 days

Within 50 km of this epicentre, a magnitude ≥ 3 earthquake has occurred on average this often: 156 events in the last 11 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.

16985.7
Monti Iblei settentrionali earthquake
1 January 1698 · 47 km from here
VII-VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
16245.6
Monti Iblei settentrionali earthquake
3 October 1624 · 47 km from here
IXDestructive: many buildings partly or fully collapse.
18185.3
Monti Madonie earthquake
8 September 1818 · 41 km from here
VII-VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
19675.3
Monti Nebrodi earthquake
31 October 1967 · 26 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

Gela-Catania

The epicentre lies about 25 km from Gela-Catania, one of the seismic structures mapped by INGV geologists.

estimated maximum magnitude 7.1between 3 and 10 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

2.0
7 km West of Agira
3 km West · 37 km
94 months ago
30 Sept, 08:29
2.8
2 km North-West of San Teodoro
29 km North-East · 34 km
94 months ago
28 Sept, 16:45
2.5
1 km North of San Teodoro
29 km North-East · 32 km
94 months ago
28 Sept, 16:41
1.6
7 km South of Castel di Lucio
26 km North-West · 67 km
94 months ago
12 Sept, 00:42
3.3
4 km North-West of Capizzi
29 km North · 7 km
93 months ago
26 Oct, 10:28
2.7
5 km North-West of Capizzi
29 km North · 5 km
93 months ago
26 Oct, 14:23
1.3
3 km West of Capizzi
25 km North · 11 km
93 months ago
26 Oct, 14:31
1.7
8 km North-West of Troina
22 km North-East · 32 km
95 months ago
2 Sept, 16:38

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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