All earthquakes
1.5
very light
EARTHQUAKE DETAILS

1 km South of Gignese

41 months ago · 15 Apr, 21:07

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

Stronger than 68% of Italian events in the past year

Where

1 km South of GigneseEarthquakes in the province of Verbano-Cusio-OssolaEarthquakes 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

1 events
Magnitude:lightweakmoderatestrong

The energy released

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

2.7kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×178 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 ≈ 13 s

Animation sped up ~2× compared to reality.

  • Varese
    25 km from the epicentre
    first tremor in ~5 s
    main shaking in ~8 s
  • Gallarate
    32 km from the epicentre
    first tremor in ~6 s
    main shaking in ~10 s
  • Busto Arsizio
    39 km from the epicentre
    first tremor in ~7 s
    main shaking in ~12 s
  • Legnano
    43 km from the epicentre
    first tremor in ~8 s
    main shaking in ~13 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

14 km
medium depth
1.5 times the height of Mount Everest

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

in line with the area average (~12 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?

Isolated quake

In the 30 days around this event no other quakes were recorded within 30 km: a one-off episode, very common in Italy.

Activity in the area right now (30 km radius)
0
last 24 hours
0
last 7 days
0
last 30 days

No other quakes within 30 km in the 30 days around the event.

How often does it happen here?

about every ~1.7 years

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 7 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.

19364.5
Biellese earthquake
17 October 1936 · 49 km from here
VI-VIIVery strong: hard to stand; chimneys and roof tiles fall, serious damage to weaker buildings.
19934.3
Val d'Ossola earthquake
14 June 1993 · 20 km from here
V-VIStrong: felt by everyone, many get scared; objects fall, first light damage to buildings.
18804.2
Biellese earthquake
2 August 1880 · 48 km from here
VRather strong: felt by almost everyone; hanging objects swing.
18914.0
Val d'Ossola earthquake
20 December 1891 · 42 km from here
VRather strong: felt by almost everyone; hanging objects swing.

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

The closest seismic structure

Western Valais

The epicentre lies about 62 km from Western Valais, one of the seismic structures mapped by INGV geologists.

estimated maximum magnitude 7.0between 3 and 15 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).

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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