All earthquakes
1.5
very light
EARTHQUAKE DETAILS

Golfo di Trieste (Trieste, Gorizia, Udine)

61 months ago · 1 Sept, 06:25

A very light earthquake, probably not felt by people. Being deep, it is felt less at the surface.

Stronger than 68% of Italian events in the past year

Where

Golfo di Trieste (Trieste, Gorizia, Udine)Earthquakes in the province of UdineEarthquakes in Friuli-Venezia Giulia

Epicentre at sea

The epicentre is at sea: for the same magnitude, the shaking is felt less on land, because the energy fades along the way before reaching the coast.

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

2 events
Magnitude:lightweakmoderatestrong

The energy released

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

2.7kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×178 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 ≈ 22 s

Animation sped up ~4× compared to reality.

  • Trieste
    45 km from the epicentre
    first tremor in ~9 s
    main shaking in ~15 s
  • Udine
    68 km from the epicentre
    first tremor in ~12 s
    main shaking in ~21 s
  • Pordenone
    72 km from the epicentre
    first tremor in ~13 s
    main shaking in ~22 s
  • Venezia
    72 km from the epicentre
    first tremor in ~13 s
    main shaking in ~22 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

31 km
deep
3.5 times the height of Mount Everest

Being deep, it is felt less at the surface.

deeper than the area average (~17 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?

Mainshock

It is the strongest quake of its sequence: so far it has been followed by 0 aftershocks within 30 km. Aftershocks tend to fade in number and strength over time.

Activity in the area right now (30 km radius)
0
last 24 hours
0
last 7 days
1
last 30 days
1 before0 after
this quake
Strongest of the sequence1.4

How often does it happen here?

about every ~7 months

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 19 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.

19684.2
Adriatico settentrionale earthquake
17 September 1968 · 39 km from here
15294.2
Friuli earthquake
14 April 1529 · 50 km from here
V-VIStrong: felt by everyone, many get scared; objects fall, first light damage to buildings.
19104.1
Friuli earthquake
5 April 1910 · 49 km from here
VRather strong: felt by almost everyone; hanging objects swing.

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

The closest seismic structure

Southern Trieste Gulf

The epicentre lies about 35 km from Southern Trieste Gulf, one of the seismic structures mapped by INGV geologists.

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).

Other quakes in the area

1.4
61 months ago
31 Aug, 07:42

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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