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2.6
light
EARTHQUAKE DETAILS

M2.6 offshore earthquake

7 years ago · 25 Nov 2018, 03:40

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

Stronger than 96% of Italian events in the past year

Where

Nearest Italian town: Acquedolci (ME)Earthquakes in the province of MessinaEarthquakes 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

4 events
Magnitude:lightweakmoderatestrong

The energy released

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

120kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×4 its energy
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 ≈ 29 s

Animation sped up ~5× compared to reality.

  • Bagheria
    88 km from the epicentre
    first tremor in ~15 s
    main shaking in ~26 s
  • Messina
    93 km from the epicentre
    first tremor in ~16 s
    main shaking in ~28 s
  • Acireale
    96 km from the epicentre
    first tremor in ~17 s
    main shaking in ~28 s
  • Caltanissetta
    99 km from the epicentre
    first tremor in ~17 s
    main shaking in ~29 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.

deeper than the area average (~20 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?

Foreshock

In hindsight it was a foreshock: 7 years ago the same area had a stronger quake (M3.0). This can only be said after the fact — it was not predictable beforehand.

3.0
The mainshock
23 km West of Leni
7 years ago · 16 Dec 2018, 13:34
Activity in the area right now (30 km radius)
0
last 24 hours
2
last 7 days
11
last 30 days
0 before3 after
this quake
Strongest of the sequence3.0

How often does it happen here?

about every ~11 days

Within 50 km of this epicentre, a magnitude ≥ 2.5 earthquake has occurred on average this often: 386 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 · 15 km from here
VIII-IXDestructive: many buildings partly or fully collapse.
19805.7
Tirreno meridionale earthquake
28 May 1980 · 27 km from here
VI-VIIVery strong: hard to stand; chimneys and roof tiles fall, serious damage to weaker buildings.
16135.6
Monti Nebrodi earthquake
25 August 1613 · 34 km from here
IXDestructive: many buildings partly or fully collapse.
20045.4
Isole Eolie earthquake
5 May 2004 · 41 km from here
IVModerate: felt by many indoors; glasses and dishes rattle.

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

The closest seismic structure

Southern Tyrrhenian S

The epicentre lies about 10 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

2.8
Costa Siciliana nord-orientale (Messina)
8 km East · 216 km
7 years ago
7 Dec 2018, 11:58
3.0
23 km West of Leni
28 km North-East · 253 km
7 years ago
16 Dec 2018, 13:34
2.3
15 km North of Capo d'Orlando
27 km East · 139 km
7 years ago
20 Dec 2018, 03:19

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).