All earthquakes
1.7
very light
EARTHQUAKE DETAILS

3 km North-East of Petritoli

5 months ago · 20 Mar, 21:29

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

Stronger than 78% of Italian events in the past year

Where

3 km North-East of PetritoliEarthquakes 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

61 events
Magnitude:lightweakmoderatestrong

The energy released

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

5.4kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×89 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 ≈ 23 s

Animation sped up ~4× compared to reality.

  • Teramo
    47 km from the epicentre
    first tremor in ~9 s
    main shaking in ~15 s
  • Ancona
    58 km from the epicentre
    first tremor in ~11 s
    main shaking in ~18 s
  • Foligno
    72 km from the epicentre
    first tremor in ~13 s
    main shaking in ~22 s
  • Montesilvano
    76 km from the epicentre
    first tremor in ~13 s
    main shaking in ~23 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

27 km
medium depth
3 times the height of Mount Everest

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

deeper than the area average (~11 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: 4 months ago the same area had a stronger quake (M3.0). This can only be said after the fact — it was not predictable beforehand.

3.0
The mainshock
3 km North-West of Sant'Angelo in Pontano
4 months ago · 18 Apr, 14:53
Activity in the area right now (30 km radius)
0
last 24 hours
4
last 7 days
24
last 30 days
96 before40 after
this quake
Strongest of the sequence3.0

How often does it happen here?

about every ~1 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 5571 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.

17996.2
Appennino marchigiano earthquake
28 July 1799 · 45 km from here
IX-XCompletely destructive: most buildings are destroyed.
18735.8
Appennino marchigiano earthquake
12 March 1873 · 35 km from here
IXDestructive: many buildings partly or fully collapse.
19435.7
Ascolano earthquake
3 October 1943 · 16 km from here
IXDestructive: many buildings partly or fully collapse.
19725.5
Marche meridionali earthquake
26 November 1972 · 22 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

Southern Marche

The epicentre lies about 3 km from Southern Marche, one of the seismic structures mapped by INGV geologists.

estimated maximum magnitude 6.9between 4 and 11 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

2.2
2 km North-West of Ponzano di Fermo
6 km North-West · 23 km
5 months ago
20 Mar, 21:30
1.9
5 months ago
20 Mar, 21:31
1.9
4 km East of Ponzano di Fermo
4 km North-East · 23 km
5 months ago
20 Mar, 21:37
1.3
1 km East of Fermo
9 km North-West · 20 km
5 months ago
20 Mar, 22:21
1.6
4 km East of Rapagnano
9 km North · 21 km
5 months ago
20 Mar, 22:28
1.8
5 months ago
20 Mar, 22:30
1.3
0 km West of Rapagnano
10 km North-West · 20 km
5 months ago
20 Mar, 23:18
1.2
5 months ago
20 Mar, 23:19
1.2
5 months ago
20 Mar, 17:49
1.7
5 months ago
21 Mar, 02:22

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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