All earthquakes
1.5
very light
EARTHQUAKE DETAILS

14 km North of Sirolo

6 months ago · 20 Feb, 13:39

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 68% of Italian events in the past year

Where

14 km North of SiroloEarthquakes in the province of AnconaEarthquakes 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

5 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 ≈ 28 s

Animation sped up ~5× compared to reality.

  • Ancona
    14 km from the epicentre
    first tremor in ~3 s
    main shaking in ~5 s
  • Fano
    56 km from the epicentre
    first tremor in ~9 s
    main shaking in ~16 s
  • Pesaro
    69 km from the epicentre
    first tremor in ~12 s
    main shaking in ~20 s
  • Foligno
    99 km from the epicentre
    first tremor in ~17 s
    main shaking in ~28 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

7 km
shallow

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

in line with 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?

Aftershock

It is an aftershock: it follows a stronger quake (M2.6, 6 months ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

2.6
The mainshock
3 km North-East of Loreto
6 months ago · 17 Feb, 19:16
Activity in the area right now (30 km radius)
0
last 24 hours
0
last 7 days
1
last 30 days
3 before1 after
this quake
Strongest of the sequence2.6

How often does it happen here?

about every ~7 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 641 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.

19305.8
Senigallia earthquake
30 October 1930 · 21 km from here
VIII-IXDestructive: many buildings partly or fully collapse.
16905.6
Costa anconetana earthquake
23 December 1690 · 10 km from here
VIII-IXDestructive: many buildings partly or fully collapse.
12695.6
Costa anconetana earthquake
September 1269 · 10 km from here
VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
19245.5
Senigallia earthquake
2 January 1924 · 42 km from here
VII-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

Conero offshore

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

estimated maximum magnitude 6.6between 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

2.2
14 km North of Sirolo
1 km East · 6 km
6 months ago
23 Feb, 04:33
1.6
7 km East of Numana
18 km South-East · 11 km
6 months ago
17 Feb, 19:23
2.6
3 km North-East of Loreto
20 km South · 10 km
6 months ago
17 Feb, 19:16
1.3
15 km North of Ancona
12 km North-West · 0 km
7 months ago
11 Feb, 11:56

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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