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2.2
light
EARTHQUAKE DETAILS

M2.2 offshore earthquake

10 years ago · 16 Nov 2015, 08:51

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

Stronger than 92% of Italian events in the past year

Where

Nearest Italian town: Priolo Gargallo (SR)Earthquakes in the province of SiracusaEarthquakes in Sicilia

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

13 events
Magnitude:lightweakmoderatestrong

The energy released

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

30kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×16 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.

  • Siracusa
    57 km from the epicentre
    first tremor in ~11 s
    main shaking in ~18 s
  • Acireale
    69 km from the epicentre
    first tremor in ~12 s
    main shaking in ~21 s
  • Catania
    71 km from the epicentre
    first tremor in ~13 s
    main shaking in ~22 s
  • Reggio di Calabria
    93 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

27 km
medium depth
3 times the height of Mount Everest

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

in line with the area average (~24 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 (M3.5, 10 years ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

3.5
The mainshock
Mar Ionio Meridionale [Mare]
10 years ago · 7 Nov 2015, 23:36
Activity in the area right now (30 km radius)
0
last 24 hours
1
last 7 days
2
last 30 days
9 before3 after
this quake
Strongest of the sequence3.5

How often does it happen here?

about every ~12 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 362 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.

19905.6
Sicilia sud-orientale earthquake
13 December 1990 · 33 km from here
VII-VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
19635.0
Ionio meridionale earthquake
30 September 1963 · 26 km from here
18975.0
Ionio meridionale earthquake
11 February 1897 · 45 km from here
V-VIStrong: felt by everyone, many get scared; objects fall, first light damage to buildings.
19974.5
Ionio meridionale earthquake
25 March 1997 · 12 km from here
VRather strong: felt by almost everyone; hanging objects swing.

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

The closest seismic structure

Aretusa

The epicentre sits above this source area: the deep structure where this area's earthquakes can originate.

estimated maximum magnitude 6.3between 10 and 20 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
Mar Ionio Meridionale [Mare]
9 km West · 19 km
10 years ago
15 Nov 2015, 19:48
1.7
Mar Ionio Meridionale [Mare]
6 km North-West · 37 km
10 years ago
14 Nov 2015, 15:30
2.1
Costa Siracusana (Siracusa)
16 km South-West · 23 km
10 years ago
20 Nov 2015, 00:40
1.9
Costa Siracusana (Siracusa)
19 km West · 28 km
10 years ago
11 Nov 2015, 20:44
2.2
Costa Siracusana (Siracusa)
26 km North-West · 26 km
10 years ago
11 Nov 2015, 02:36
2.1
Mar Ionio Meridionale [Mare]
3 km North-West · 29 km
10 years ago
8 Nov 2015, 19:00
2.5
Mar Ionio Meridionale [Mare]
4 km East · 22 km
10 years ago
8 Nov 2015, 13:22
2.0
Mar Ionio Meridionale [Mare]
2 km East · 21 km
10 years ago
7 Nov 2015, 23:46
2.0
Mar Ionio Meridionale [Mare]
2 km South-East · 24 km
10 years ago
7 Nov 2015, 23:42
3.5
Mar Ionio Meridionale [Mare]
8 km East · 23 km
10 years ago
7 Nov 2015, 23:36

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).