All earthquakes
1.6
very light
EARTHQUAKE DETAILS

10 km East of Porto Sant'Elpidio

32 months ago · 22 Oct, 13:32

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

Stronger than 73% of Italian events in the past year

Where

10 km East of Porto Sant'ElpidioEarthquakes in the province of FermoEarthquakes in Marche

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

3 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 ≈ 27 s

Animation sped up ~5× compared to reality.

  • Ancona
    45 km from the epicentre
    first tremor in ~8 s
    main shaking in ~14 s
  • Teramo
    71 km from the epicentre
    first tremor in ~12 s
    main shaking in ~21 s
  • Fano
    91 km from the epicentre
    first tremor in ~16 s
    main shaking in ~27 s
  • Foligno
    92 km from the epicentre
    first tremor in ~16 s
    main shaking in ~27 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

18 km
medium depth
2 times the height of Mount Everest

At this depth the shaking is felt, but rarely causes damage.

in line with the area average (~22 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: 31 months ago the same area had a stronger quake (M1.8). This can only be said after the fact — it was not predictable beforehand.

1.8
The mainshock
12 km North-East of Porto San Giorgio
31 months ago · 16 Nov, 04:44
Activity in the area right now (30 km radius)
0
last 24 hours
0
last 7 days
1
last 30 days
1 before1 after
this quake
Strongest of the sequence1.8

How often does it happen here?

about every ~11 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 393 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.

19435.7
Ascolano earthquake
3 October 1943 · 43 km from here
IXDestructive: many buildings partly or fully collapse.
16905.6
Costa anconetana earthquake
23 December 1690 · 36 km from here
VIII-IXDestructive: many buildings partly or fully collapse.
12695.6
Costa anconetana earthquake
September 1269 · 39 km from here
VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
19725.5
Marche meridionali earthquake
26 November 1972 · 49 km from here
VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.

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

The closest seismic structure

Conrad

The epicentre lies about 4 km from Conrad, one of the seismic structures mapped by INGV geologists.

estimated maximum magnitude 5.9between 2 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

1.5
9 km East of Pedaso
22 km South-East · 34 km
32 months ago
17 Oct, 12:41
1.8
31 months ago
16 Nov, 04:44

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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