All earthquakes
0.5
very light
EARTHQUAKE DETAILS

M0.5 earthquake · 4 km South-East of Silandro (BZ)

5 years ago · 2 Aug 2021, 22:36

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

Stronger than 3% of Italian events in the past year

Where

4 km South-East of SilandroEarthquakes in the province of BolzanoEarthquakes in Trentino-Alto Adige

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

9 events
Magnitude:lightweakmoderatestrong

The energy released

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

0.1kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×5,623 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 ≈ 38 s

Animation sped up ~7× compared to reality.

  • Bolzano
    48 km from the epicentre
    first tremor in ~8 s
    main shaking in ~14 s
  • Trento
    69 km from the epicentre
    first tremor in ~12 s
    main shaking in ~20 s
  • Brescia
    128 km from the epicentre
    first tremor in ~22 s
    main shaking in ~37 s
  • Verona
    132 km from the epicentre
    first tremor in ~22 s
    main shaking in ~38 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
1.6 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?

Aftershock

It is an aftershock: it follows a stronger quake (M1.6, 5 years ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

1.6
The mainshock
3 km North of Valfurva
5 years ago · 13 Jul 2021, 20:28
Activity in the area right now (30 km radius)
0
last 24 hours
3
last 7 days
11
last 30 days
3 before5 after
this quake
Strongest of the sequence1.6

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: 40 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.

16225.4
Bassa Engadina, Ftan earthquake
3 August 1622 · 47 km from here
19025.0
Alpi Retiche earthquake
19 June 1902 · 43 km from here
VI-VIIVery strong: hard to stand; chimneys and roof tiles fall, serious damage to weaker buildings.
19614.9
Val Monastero earthquake
9 August 1961 · 39 km from here
V-VIStrong: felt by everyone, many get scared; objects fall, first light damage to buildings.
20014.8
Val Venosta earthquake
17 July 2001 · 25 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

Brenner

The epicentre lies about 50 km from Brenner, one of the seismic structures mapped by INGV geologists.

estimated maximum magnitude 7.2between 4 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).

Other quakes in the area

1.3
5 km East of Malles Venosta
16 km North-West · 14 km
5 years ago
12 Aug 2021, 10:03
1.4
11 km North-West of Rabbi
18 km South-West · 10 km
5 years ago
14 Aug 2021, 15:44
1.2
3 km West of Malé
29 km South · 12 km
5 years ago
18 Aug 2021, 05:21
0.8
4 km North of Laces
8 km East · 16 km
5 years ago
17 Jul 2021, 18:19
1.6
3 km North of Valfurva
28 km South-West · 10 km
5 years ago
13 Jul 2021, 20:28
1.2
9 km East of Malles Venosta
13 km North-West · 16 km
5 years ago
25 Aug 2021, 08:26
0.8
8 km South-West of Tubre
28 km West · 11 km
5 years ago
29 Aug 2021, 05:54
0.8
4 km South of Lasa
9 km South-West · 11 km
5 years ago
4 Jul 2021, 03:06

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).