All earthquakes
1.6
very light
EARTHQUAKE DETAILS

M1.6 earthquake · 3 km North-East of Monno (BS)

5 years ago · 10 Jul 2021, 04:28

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 74% of Italian events in the past year

Where

3 km North-East of MonnoEarthquakes in the province of BresciaEarthquakes 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

8 events
Magnitude:lightweakmoderatestrong

The energy released

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

3.8kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×126 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 ≈ 24 s

Animation sped up ~4× compared to reality.

  • Trento
    64 km from the epicentre
    first tremor in ~11 s
    main shaking in ~18 s
  • Bergamo
    82 km from the epicentre
    first tremor in ~14 s
    main shaking in ~23 s
  • Brescia
    82 km from the epicentre
    first tremor in ~14 s
    main shaking in ~24 s
  • Bolzano
    83 km from the epicentre
    first tremor in ~14 s
    main shaking in ~24 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?

Foreshock

In hindsight it was a foreshock: 5 years ago the same area had a stronger quake (M2.2). This can only be said after the fact — it was not predictable beforehand.

2.2
The mainshock
5 km East of Mazzo di Valtellina
5 years ago · 25 Jul 2021, 13:57
Activity in the area right now (30 km radius)
0
last 24 hours
0
last 7 days
4
last 30 days
2 before5 after
this quake
Strongest of the sequence2.2

How often does it happen here?

about every ~3 months

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 45 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.

18514.9
Valli Giudicarie earthquake
3 August 1851 · 40 km from here
19994.8
Alpi Retiche earthquake
29 December 1999 · 32 km from here
V-VIStrong: felt by everyone, many get scared; objects fall, first light damage to buildings.
19314.8
Valli Giudicarie earthquake
14 April 1931 · 41 km from here
VIStrong: felt by everyone, many get scared; objects fall, first light damage to buildings.
19074.8
Alpi Retiche earthquake
20 April 1907 · 29 km from here
VIStrong: felt by everyone, many get scared; objects fall, first light damage to buildings.

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

The closest seismic structure

Giudicarie

The epicentre lies about 47 km from Giudicarie, one of the seismic structures mapped by INGV geologists.

estimated maximum magnitude 6.8between 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

1.6
5 km South of Sondalo
5 km North-East · 11 km
5 years ago
10 Jul 2021, 00:23
1.6
3 km North of Valfurva
24 km North-East · 10 km
5 years ago
13 Jul 2021, 20:28
0.5
1 km West of Lovero
9 km West · 8 km
5 years ago
21 Jul 2021, 21:17
1.0
4 km North-East of Valdaone
29 km South-East · 9 km
5 years ago
22 Jul 2021, 03:31
1.0
7 km North-West of Peio
26 km North-East · 10 km
5 years ago
27 Jun 2021, 07:03
2.2
5 years ago
25 Jul 2021, 13:57
1.6
5 km East of Mazzo di Valtellina
2 km North-West · 10 km
5 years ago
30 Jul 2021, 22:29

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).