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2.8
light
EARTHQUAKE DETAILS

10 km East of Formazza

27 months ago · 18 Mar, 16:52

A light earthquake, rarely felt by people. At this depth the shaking is felt, but rarely causes damage.

Stronger than 97% of Italian events in the past yearNo. 5 of the year in Piemonte

Where

10 km East of FormazzaEarthquakes in the province of Verbano-Cusio-OssolaEarthquakes in Piemonte

How far away could it be felt?

An estimate of how far people may have felt this quake.

  • up to ~4 km · felt only by some, at rest

The coloured rings on the map below show these distances.

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.

239kgof TNT equivalent
1.0 lightning bolt
M3
A magnitude 3 earthquake releases ×2 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 ≈ 27 s

Animation sped up ~5× compared to reality.

  • Varese
    68 km from the epicentre
    first tremor in ~11 s
    main shaking in ~20 s
  • Como
    80 km from the epicentre
    first tremor in ~13 s
    main shaking in ~23 s
  • Gallarate
    85 km from the epicentre
    first tremor in ~14 s
    main shaking in ~25 s
  • Busto Arsizio
    92 km from the epicentre
    first tremor in ~16 s
    main shaking in ~27 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

11 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?

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 ~1.6 years

Within 50 km of this epicentre, a magnitude ≥ 2.5 earthquake has occurred on average this often: 7 events in the last 11 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.

17555.7
Vallese, Brig-Naters earthquake
9 December 1755 · 42 km from here
18375.4
Berna, Birgisch earthquake
24 January 1837 · 43 km from here
19245.2
Vallese, Brig earthquake
15 April 1924 · 44 km from here
19605.0
Vallese earthquake
23 March 1960 · 38 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 Valais

The epicentre lies about 46 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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