All earthquakes
1.6
very light
EARTHQUAKE DETAILS

17 km North-East of Drenchia

57 months ago · 31 Dec, 10:10

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

17 km North-East of DrenchiaEarthquakes in the province of UdineEarthquakes in Friuli-Venezia Giulia

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.

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 ≈ 39 s

Animation sped up ~7× compared to reality.

  • Udine
    47 km from the epicentre
    first tremor in ~8 s
    main shaking in ~14 s
  • Trieste
    72 km from the epicentre
    first tremor in ~12 s
    main shaking in ~21 s
  • Pordenone
    95 km from the epicentre
    first tremor in ~16 s
    main shaking in ~27 s
  • Treviso
    138 km from the epicentre
    first tremor in ~23 s
    main shaking in ~39 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 (~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: 57 months ago the same area had a stronger quake (M1.7). This can only be said after the fact — it was not predictable beforehand.

1.7
The mainshock
24 km East of Drenchia
57 months ago · 1 Jan, 22:45
Activity in the area right now (30 km radius)
0
last 24 hours
0
last 7 days
3
last 30 days
3 before2 after
this quake
Strongest of the sequence1.7

How often does it happen here?

about every ~29 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 145 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 · 29 km from here
IX-XCompletely destructive: most buildings are destroyed.
15116.3
Friuli-Slovenia earthquake
26 March 1511 · 44 km from here
IXDestructive: many buildings partly or fully collapse.
16906.2
Carinthia, Villach earthquake
4 December 1690 · 40 km from here
VIII-IXDestructive: many buildings partly or fully collapse.
19766.0
Friuli earthquake
15 September 1976 · 47 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

Bovec-Tolminka Springs

The epicentre lies about 4 km from Bovec-Tolminka Springs, one of the seismic structures mapped by INGV geologists.

estimated maximum magnitude 6.9between 1 and 10 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

1.7
24 km East of Drenchia
18 km South-East · 10 km
57 months ago
1 Jan, 22:45
1.1
12 km South-East of Stregna
26 km South · 8 km
57 months ago
17 Dec, 13:58
1.1
9 km South-East of Stregna
25 km South-West · 4 km
56 months ago
18 Jan, 14:00
1.2
58 months ago
3 Dec, 01:50
1.6
Slovenia (SLOVENIA)
26 km East · 10 km
58 months ago
1 Dec, 10:18

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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