All earthquakes
0.7
very light
EARTHQUAKE DETAILS

8 km South of Pietraporzio

41 months ago · 28 Apr, 06:34

A very light earthquake, probably not felt by people. At this depth the shaking is felt, but rarely causes damage.

Stronger than 11% of Italian events in the past year

Where

8 km South of PietraporzioEarthquakes in the province of CuneoEarthquakes in Piemonte

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.

0.2kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×2,818 its energy
M0this quakeM2

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 ≈ 31 s

Animation sped up ~6× compared to reality.

  • Cuneo
    47 km from the epicentre
    first tremor in ~8 s
    main shaking in ~14 s
  • Sanremo
    78 km from the epicentre
    first tremor in ~13 s
    main shaking in ~22 s
  • Moncalieri
    97 km from the epicentre
    first tremor in ~16 s
    main shaking in ~28 s
  • Torino
    109 km from the epicentre
    first tremor in ~18 s
    main shaking in ~31 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

10 km
medium depth
1.1 times the height of Mount Everest

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

in line with the area average (~11 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: 40 months ago the same area had a stronger quake (M2.0). This can only be said after the fact — it was not predictable beforehand.

2.0
The mainshock
10 km West of Acceglio
40 months ago · 2 May, 03:31
Activity in the area right now (30 km radius)
1
last 24 hours
4
last 7 days
8
last 30 days
9 before4 after
this quake
Strongest of the sequence2.0

How often does it happen here?

about every ~16 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 265 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.

15645.8
Lantosque earthquake
20 July 1564 · 34 km from here
VIII-IXDestructive: many buildings partly or fully collapse.
16445.7
Alpes Niçoises earthquake
15 February 1644 · 36 km from here
VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
16185.6
Alpes Niçoises earthquake
18 January 1618 · 41 km from here
VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
19595.4
Ubaye earthquake
5 April 1959 · 35 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

Brianconnais

The epicentre lies about 21 km from Brianconnais, one of the seismic structures mapped by INGV geologists.

estimated maximum magnitude 7.2between 5 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

1.1
6 km South-East of Vinadio
13 km East · 11 km
41 months ago
28 Apr, 08:27
2.0
10 km West of Acceglio
29 km North-West · 10 km
40 months ago
2 May, 03:31
0.9
4 km South-East of Vinadio
12 km East · 11 km
41 months ago
21 Apr, 21:46
1.4
6 km South-West of Acceglio
21 km North · 11 km
41 months ago
20 Apr, 08:14
1.4
3 km South-West of Pradleves
26 km North-East · 14 km
40 months ago
10 May, 05:54
0.8
10 km South-East of Vinadio
17 km East · 10 km
40 months ago
13 May, 02:14
1.2
4 km South-West of Aisone
16 km East · 10 km
41 months ago
12 Apr, 17:35
1.9
6 km South-West of Aisone
15 km East · 8 km
41 months ago
12 Apr, 17:32
1.2
1 km West of Pradleves
27 km North-East · 11 km
41 months ago
8 Apr, 03:06
1.1
3 km South-West of Aisone
17 km East · 11 km
41 months ago
7 Apr, 01:43

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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