All earthquakes
1.9
very light
EARTHQUAKE DETAILS

Costa Calabra sud-occidentale (Catanzaro, Vibo Valentia, Reggio di Calabria)

24 months ago · 2 Sept, 18:02

A very light earthquake, probably not felt by people. Being deep, it is felt less at the surface.

Stronger than 85% of Italian events in the past year

Where

Costa Calabra sud-occidentale (Catanzaro, Vibo Valentia, Reggio di Calabria)Earthquakes in the province of Vibo ValentiaEarthquakes in Calabria

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

14 events
Magnitude:lightweakmoderatestrong

The energy released

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

11kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×45 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 ≈ 34 s

Animation sped up ~6× compared to reality.

  • Lamezia Terme
    53 km from the epicentre
    first tremor in ~17 s
    main shaking in ~29 s
  • Cosenza
    69 km from the epicentre
    first tremor in ~19 s
    main shaking in ~32 s
  • Messina
    75 km from the epicentre
    first tremor in ~19 s
    main shaking in ~33 s
  • Catanzaro
    80 km from the epicentre
    first tremor in ~20 s
    main shaking in ~34 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

88 km
deep
9.9 times the height of Mount Everest

Being deep, it is felt less at the surface.

shallower than the area average (~112 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: 23 months ago the same area had a stronger quake (M2.7). This can only be said after the fact — it was not predictable beforehand.

2.7
The mainshock
24 km West of Ricadi
23 months ago · 27 Sept, 11:20
Activity in the area right now (30 km radius)
0
last 24 hours
2
last 7 days
14
last 30 days
5 before8 after
this quake
Strongest of the sequence2.7

How often does it happen here?

about every ~4 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 1161 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.

19057.0
Calabria centrale earthquake
8 September 1905 · 28 km from here
X-XICatastrophic: very few buildings remain standing; landslides and ground cracks.
19285.9
Calabria centro-meridionale earthquake
7 March 1928 · 29 km from here
VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
20065.8
Tirreno meridionale earthquake
26 October 2006 · 27 km from here
19415.3
Isola di Stromboli earthquake
22 May 1941 · 39 km from here
VII-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

Sant'Eufemia

The epicentre lies about 34 km from Sant'Eufemia, one of the seismic structures mapped by INGV geologists.

estimated maximum magnitude 7.1between 1 and 12 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

2.4
Tirreno Meridionale [Mare]
24 km South-West · 115 km
24 months ago
5 Sept, 04:28
1.6
16 km South-West of Falerna
30 km East · 39 km
24 months ago
12 Sept, 11:10
2.0
Tirreno Meridionale [Mare]
8 km North-West · 174 km
24 months ago
16 Sept, 11:23
2.0
25 months ago
19 Aug, 15:45
2.1
24 km North-West of Ricadi
15 km South-West · 160 km
24 months ago
17 Sept, 02:54
1.9
18 km West of Falerna
27 km East · 40 km
24 months ago
20 Sept, 06:50
2.2
23 km North-West of Ricadi
15 km South · 92 km
25 months ago
13 Aug, 23:31
2.7
24 km West of Ricadi
26 km South-West · 83 km
23 months ago
27 Sept, 11:20
2.2
Tirreno Meridionale [Mare]
13 km West · 75 km
23 months ago
29 Sept, 19:44

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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