All earthquakes
2.8
light
EARTHQUAKE DETAILS

M2.8 earthquake outside Italy

6 years ago · 21 Aug 2020, 17:49

A light earthquake, rarely felt by people. At only a few km deep the shaking is felt more sharply at the surface.

Where

Nearest Italian town: Savogna (UD)Earthquakes in the province of UdineEarthquakes in Friuli-Venezia Giulia

Epicentre abroad

The epicentre lies outside Italy's borders. The quake appears here because the INGV seismic network also records events close to Italy, which can be felt on Italian territory.

How far away could it be felt?

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

  • up to ~5 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

17 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 ≈ 35 s

Animation sped up ~6× compared to reality.

  • Udine
    32 km from the epicentre
    first tremor in ~6 s
    main shaking in ~10 s
  • Trieste
    72 km from the epicentre
    first tremor in ~12 s
    main shaking in ~21 s
  • Pordenone
    78 km from the epicentre
    first tremor in ~13 s
    main shaking in ~23 s
  • Treviso
    122 km from the epicentre
    first tremor in ~20 s
    main shaking in ~35 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

9 km
shallow
1 times the height of Mount Everest

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

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 (M3.0, 6 years ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

3.0
The mainshock
12 km North of Drenchia
6 years ago · 2 Aug 2020, 18:04
Activity in the area right now (30 km radius)
1
last 24 hours
1
last 7 days
6
last 30 days
13 before3 after
this quake
Strongest of the sequence3.0

How often does it happen here?

about every ~56 days

Within 50 km of this epicentre, a magnitude ≥ 2.5 earthquake has occurred on average this often: 77 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.

13486.6
Alpi Giulie earthquake
25 January 1348 · 27 km from here
IX-XCompletely destructive: most buildings are destroyed.
19766.5
Friuli earthquake
6 May 1976 · 33 km from here
IX-XCompletely destructive: most buildings are destroyed.
15116.3
Friuli-Slovenia earthquake
26 March 1511 · 26 km from here
IXDestructive: many buildings partly or fully collapse.
16906.2
Carinthia, Villach earthquake
4 December 1690 · 48 km from here
VIII-IXDestructive: many buildings partly or fully collapse.

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

The closest seismic structure

Stol

The epicentre sits above this source area: the deep structure where this area's earthquakes can originate.

estimated maximum magnitude 6.1between 1 and 7 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

1.0
13 km East of Resia
7 km North-West · 11 km
6 years ago
20 Aug 2020, 01:35
0.7
13 km South-East of Stregna
27 km South-East · 8 km
6 years ago
17 Aug 2020, 13:59
1.6
6 years ago
14 Aug 2020, 14:39
1.8
13 km North of Pulfero
6 km North-West · 11 km
6 years ago
13 Aug 2020, 10:32
0.7
12 km South-East of Stregna
27 km South-East · 8 km
6 years ago
12 Aug 2020, 13:59
1.4
1 km East of Cividale del Friuli
22 km South-West · 10 km
6 years ago
1 Sept 2020, 01:27
1.6
2 km East of Cividale del Friuli
20 km South-West · 10 km
6 years ago
1 Sept 2020, 05:25
1.4
13 km East of Resia
7 km North-West · 10 km
6 years ago
10 Aug 2020, 21:15
1.3
3 km West of Prepotto
21 km South · 18 km
6 years ago
1 Sept 2020, 22:47
0.7
13 km North of Pulfero
6 km North-West · 11 km
6 years ago
9 Aug 2020, 03:19

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).