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2.6
light
EARTHQUAKE DETAILS

M2.6 earthquake · 16 km North-West of Tropea (VV)

11 years ago · 22 Mar 2015, 20:18

A light earthquake, rarely felt by people. Being deep, it is felt less at the surface.

Stronger than 96% of Italian events in the past year

Where

16 km North-West of TropeaEarthquakes in the province of Vibo ValentiaEarthquakes in Calabria

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

11 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 ≈ 51 s

Animation sped up ~10× compared to reality.

  • Lamezia Terme
    54 km from the epicentre
    first tremor in ~28 s
    main shaking in ~49 s
  • Messina
    64 km from the epicentre
    first tremor in ~29 s
    main shaking in ~50 s
  • Reggio di Calabria
    71 km from the epicentre
    first tremor in ~30 s
    main shaking in ~51 s
  • Cosenza
    76 km from the epicentre
    first tremor in ~30 s
    main shaking in ~51 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

162 km
deep
18 times the height of Mount Everest

Being deep, it is felt less at the surface.

deeper than the area average (~86 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: 11 years ago the same area had a stronger quake (M4.3). This can only be said after the fact — it was not predictable beforehand.

4.3
The mainshock
Tirreno Meridionale [Mare]
11 years ago · 15 Apr 2015, 18:57
Activity in the area right now (30 km radius)
1
last 24 hours
1
last 7 days
9
last 30 days
5 before5 after
this quake
Strongest of the sequence4.3

How often does it happen here?

about every ~10 days

Within 50 km of this epicentre, a magnitude ≥ 2.5 earthquake has occurred on average this often: 451 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 · 25 km from here
X-XICatastrophic: very few buildings remain standing; landslides and ground cracks.
17836.7
Calabria centrale earthquake
7 February 1783 · 45 km from here
X-XICatastrophic: very few buildings remain standing; landslides and ground cracks.
16596.6
Calabria centrale earthquake
5 November 1659 · 45 km from here
XCompletely destructive: most buildings are destroyed.
17916.1
Calabria centrale earthquake
13 October 1791 · 48 km from here
IXDestructive: many buildings partly or fully collapse.

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

The closest seismic structure

Sant'Eufemia

The epicentre lies about 26 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

1.9
Tirreno Meridionale [Mare]
17 km West · 90 km
11 years ago
15 Mar 2015, 04:49
2.4
24 km West of Ricadi
22 km South-West · 153 km
11 years ago
11 Mar 2015, 19:04
2.3
Tirreno Meridionale [Mare]
25 km North-West · 91 km
11 years ago
7 Mar 2015, 10:59
1.8
Tirreno Meridionale [Mare]
24 km West · 76 km
11 years ago
11 Apr 2015, 04:45
3.1
Costa Calabra sud-occidentale (Catanzaro, Vibo Valentia, Reggio di Calabria)
25 km North · 222 km
11 years ago
12 Apr 2015, 03:43
1.8
18 km South-West of Ricadi
24 km South · 56 km
11 years ago
2 Mar 2015, 09:44
1.9
18 km North-West of Ricadi
4 km South-West · 162 km
11 years ago
28 Feb 2015, 21:28
1.1
23 km West of Ricadi
10 km West · 9 km
11 years ago
14 Apr 2015, 04:03
2.1
11 km North-West of Tropea
5 km East · 159 km
11 years ago
14 Apr 2015, 06:52
4.3
Tirreno Meridionale [Mare]
29 km North-West · 257 km
11 years ago
15 Apr 2015, 18:57

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).