All earthquakes
1.6
very light
EARTHQUAKE DETAILS

6 km South-West of Duino Aurisina

10 months ago · 18 Oct, 12:39

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

6 km South-West of Duino AurisinaEarthquakes in the province of TriesteEarthquakes 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

1 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 ≈ 30 s

Animation sped up ~6× compared to reality.

  • Trieste
    14 km from the epicentre
    first tremor in ~2 s
    main shaking in ~4 s
  • Udine
    48 km from the epicentre
    first tremor in ~8 s
    main shaking in ~14 s
  • Pordenone
    80 km from the epicentre
    first tremor in ~13 s
    main shaking in ~23 s
  • Venezia
    105 km from the epicentre
    first tremor in ~18 s
    main shaking in ~30 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

0 km
shallow

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

shallower than 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?

Isolated quake

In the 30 days around this event no other quakes were recorded within 30 km: a one-off episode, very common in Italy.

Activity in the area right now (30 km radius)
0
last 24 hours
0
last 7 days
0
last 30 days

No other quakes within 30 km in the 30 days around the event.

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: 44 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.

14035.6
Cividale del Friuli earthquake
6 September 1403 · 44 km from here
VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
18985.1
Valli del Natisone earthquake
20 February 1898 · 44 km from here
VIIVery strong: hard to stand; chimneys and roof tiles fall, serious damage to weaker buildings.
17165.1
Slovenia occidentale earthquake
3 February 1716 · 40 km from here
18814.9
Carniola interna earthquake
4 February 1881 · 35 km from here

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

The closest seismic structure

Southern Trieste Gulf

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

estimated maximum magnitude 6.5between 2 and 8 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).

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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