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2.1
light
EARTHQUAKE DETAILS

5 km East of Floridia

61 months ago · 17 Aug, 15:08

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

Stronger than 90% of Italian events in the past year

Where

5 km East of FloridiaEarthquakes in the province of SiracusaEarthquakes 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

14 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 ≈ 15 s

Animation sped up ~3× compared to reality.

  • Siracusa
    10 km from the epicentre
    first tremor in ~4 s
    main shaking in ~7 s
  • Modica
    33 km from the epicentre
    first tremor in ~7 s
    main shaking in ~11 s
  • Ragusa
    47 km from the epicentre
    first tremor in ~9 s
    main shaking in ~15 s
  • Catania
    47 km from the epicentre
    first tremor in ~9 s
    main shaking in ~15 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

22 km
medium depth
2.5 times the height of Mount Everest

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

in line with the area average (~18 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 (M2.8, 61 months ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

2.8
The mainshock
7 km South-West of Palazzolo Acreide
61 months ago · 16 Aug, 18:53
Activity in the area right now (30 km radius)
0
last 24 hours
1
last 7 days
4
last 30 days
8 before5 after
this quake
Strongest of the sequence2.8

How often does it happen here?

about every ~17 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 255 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.

16937.3
Sicilia sud-orientale earthquake
11 January 1693 · 16 km from here
XICatastrophic: very few buildings remain standing; landslides and ground cracks.
15426.7
Sicilia sud-orientale earthquake
10 December 1542 · 26 km from here
XCompletely destructive: most buildings are destroyed.
11696.5
Sicilia sud-orientale earthquake
4 February 1169 · 25 km from here
XCompletely destructive: most buildings are destroyed.
16936.1
Sicilia sud-orientale earthquake
9 January 1693 · 14 km from here
VIII-IXDestructive: many buildings partly or fully collapse.

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

The closest seismic structure

Monte Lauro

The epicentre lies about 9 km from Monte Lauro, one of the seismic structures mapped by INGV geologists.

estimated maximum magnitude 7.0between 3 and 15 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

2.8
61 months ago
16 Aug, 18:53
1.4
7 km North-East of Siracusa
11 km East · 26 km
61 months ago
15 Aug, 04:29
2.3
7 km North-East of Siracusa
11 km East · 26 km
61 months ago
14 Aug, 13:37
1.0
4 km West of Melilli
16 km North · 17 km
62 months ago
8 Aug, 03:01
1.8
8 km East of Noto
25 km South · 24 km
61 months ago
28 Aug, 06:45
1.4
4 km South-West of Canicattini Bagni
12 km South-West · 25 km
61 months ago
31 Aug, 03:33
1.1
1 km West of Melilli
15 km North · 1 km
62 months ago
3 Aug, 08:40
1.9
7 km South of Canicattini Bagni
13 km South-West · 26 km
61 months ago
6 Sept, 00:09
2.6
5 km South-East of Floridia
2 km South-West · 18 km
61 months ago
7 Sept, 16:02
1.4
62 months ago
24 Jul, 00:47

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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