All earthquakes
1.1
very light
EARTHQUAKE DETAILS

2 km West of Issime

83 months ago · 31 Oct, 20:57

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

Stronger than 39% of Italian events in the past year

Where

2 km West of IssimeEarthquakes in the province of AostaEarthquakes in Valle d'Aosta

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

8 events
Magnitude:lightweakmoderatestrong

The energy released

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

0.7kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×708 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 ≈ 23 s

Animation sped up ~4× compared to reality.

  • Torino
    67 km from the epicentre
    first tremor in ~11 s
    main shaking in ~19 s
  • Novara
    68 km from the epicentre
    first tremor in ~11 s
    main shaking in ~20 s
  • Gallarate
    75 km from the epicentre
    first tremor in ~13 s
    main shaking in ~22 s
  • Varese
    78 km from the epicentre
    first tremor in ~13 s
    main shaking in ~23 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
1.2 times the height of Mount Everest

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

in line with the area average (~10 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: 83 months ago the same area had a stronger quake (M2.3). This can only be said after the fact — it was not predictable beforehand.

2.3
The mainshock
8 km West of Macugnaga
83 months ago · 6 Nov, 05:02
Activity in the area right now (30 km radius)
0
last 24 hours
0
last 7 days
0
last 30 days
3 before4 after
this quake
Strongest of the sequence2.3

How often does it happen here?

about every ~4 months

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 38 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.

18925.0
Valle d'Aosta earthquake
5 March 1892 · 14 km from here
VII-VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
19684.9
Valle d'Aosta earthquake
18 June 1968 · 5 km from here
VIStrong: felt by everyone, many get scared; objects fall, first light damage to buildings.
19124.7
Canavese earthquake
31 May 1912 · 16 km from here
V-VIStrong: felt by everyone, many get scared; objects fall, first light damage to buildings.
19364.5
Biellese earthquake
17 October 1936 · 23 km from here
VI-VIIVery strong: hard to stand; chimneys and roof tiles fall, serious damage to weaker buildings.

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

The closest seismic structure

Western Monferrato

The epicentre lies about 57 km from Western Monferrato, one of the seismic structures mapped by INGV geologists.

estimated maximum magnitude 6.4between 1 and 8 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

0.9
3 km North-East of Issogne
13 km West · 10 km
83 months ago
29 Oct, 08:15
2.3
8 km West of Macugnaga
28 km North · 11 km
83 months ago
6 Nov, 05:02
0.8
2 km North-West of Issogne
15 km West · 11 km
83 months ago
6 Nov, 08:12
1.4
4 km North-West of Issime
2 km North-West · 10 km
83 months ago
7 Nov, 21:35
0.8
6 km West of Carcoforo
27 km North-East · 15 km
83 months ago
21 Oct, 23:57
1.0
1 km North-West of Issogne
14 km West · 11 km
83 months ago
21 Oct, 08:39
0.6
2 km North of Issogne
14 km West · 10 km
82 months ago
26 Nov, 11:39

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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