All earthquakes
0.9
very light
EARTHQUAKE DETAILS

2 km South of Songavazzo

78 months ago · 20 Mar, 09:34

A very light earthquake, probably not felt by people. At only a few km deep the shaking is felt more sharply at the surface.

Stronger than 23% of Italian events in the past year

Where

2 km South of SongavazzoEarthquakes in the province of BergamoEarthquakes in Lombardia

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

6 events
Magnitude:lightweakmoderatestrong

The energy released

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

0.3kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×1,413 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 ≈ 20 s

Animation sped up ~4× compared to reality.

  • Bergamo
    34 km from the epicentre
    first tremor in ~6 s
    main shaking in ~10 s
  • Brescia
    39 km from the epicentre
    first tremor in ~7 s
    main shaking in ~11 s
  • Monza
    66 km from the epicentre
    first tremor in ~11 s
    main shaking in ~19 s
  • Sesto San Giovanni
    71 km from the epicentre
    first tremor in ~12 s
    main shaking in ~20 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

7 km
shallow

At only a few km deep the shaking is felt more sharply at the surface.

in line with the area average (~9 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?

Aftershock

It is an aftershock: it follows a stronger quake (M2.5, 79 months ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

2.5
The mainshock
1 km North-East of Sovere
79 months ago · 24 Feb, 03:11
Activity in the area right now (30 km radius)
0
last 24 hours
2
last 7 days
2
last 30 days
2 before3 after
this quake
Strongest of the sequence2.5

How often does it happen here?

about every ~51 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 84 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.

19015.4
Garda occidentale earthquake
30 October 1901 · 46 km from here
VII-VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
10655.1
Brescia earthquake
27 March 1065 · 38 km from here
VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
20045.0
Garda occidentale earthquake
24 November 2004 · 42 km from here
VII-VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
18925.0
Garda occidentale earthquake
5 January 1892 · 45 km from here
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 S-Alps internal thrust

The epicentre lies about 25 km from Western S-Alps internal thrust, one of the seismic structures mapped by INGV geologists.

estimated maximum magnitude 6.9between 5 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

1.1
1 km South of Bossico
3 km South · 8 km
78 months ago
28 Mar, 22:59
1.4
2 km South-West of Pisogne
11 km South-East · 2 km
79 months ago
11 Mar, 10:26
1.1
1 km South-West of Brione
26 km South-East · 8 km
78 months ago
6 Apr, 03:43
1.3
3 km South-West of Pisogne
10 km South-East · 2 km
78 months ago
8 Apr, 10:10
2.5
1 km North-East of Sovere
3 km South-West · 6 km
79 months ago
24 Feb, 03:11

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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