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2.1
light
EARTHQUAKE DETAILS

5 km North-East of Pennabilli

4 days ago · 20 Aug, 22:11

A light earthquake, rarely felt by people. At this depth the shaking is felt, but rarely causes damage.

Stronger than 90% of Italian events in the past year

Where

5 km North-East of PennabilliEarthquakes in the province of RiminiEarthquakes in Emilia-Romagna

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

29 events
Magnitude:lightweakmoderatestrong

The energy released

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

21kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×22 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 ≈ 15 s

Animation sped up ~3× compared to reality.

  • Rimini
    29 km from the epicentre
    first tremor in ~6 s
    main shaking in ~10 s
  • Cesena
    32 km from the epicentre
    first tremor in ~6 s
    main shaking in ~10 s
  • Pesaro
    42 km from the epicentre
    first tremor in ~8 s
    main shaking in ~13 s
  • Forlì
    49 km from the epicentre
    first tremor in ~9 s
    main shaking in ~15 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.

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?

Mainshock

It is the strongest quake of its sequence: so far it has been followed by 3 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
6
last 7 days
21
last 30 days
25 before3 after
nowthis quake
Strongest of the sequence2.0

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: 598 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.

17816.5
Cagliese earthquake
3 June 1781 · 30 km from here
XCompletely destructive: most buildings are destroyed.
13526.3
Alta Valtiberina earthquake
25 December 1352 · 42 km from here
IXDestructive: many buildings partly or fully collapse.
16616.0
Appennino forlivese earthquake
22 March 1661 · 40 km from here
XCompletely destructive: most buildings are destroyed.
13896.0
Alta Valtiberina earthquake
18 October 1389 · 33 km from here
IXDestructive: many buildings partly or fully collapse.

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

The closest seismic structure

Urbino-Camerino

The epicentre lies about 7 km from Urbino-Camerino, one of the seismic structures mapped by INGV geologists.

estimated maximum magnitude 6.9between 3 and 9 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

2.0
4 days ago
20 Aug, 21:36
1.4
4 km East of Pennabilli
1 km South-West · 16 km
4 days ago
21 Aug, 14:09
1.6
6 km South of Badia Tedalda
20 km South-West · 11 km
4 days ago
21 Aug, 16:20
1.0
6 days ago
18 Aug, 22:03
0.9
2 days ago
23 Aug, 04:50
1.1
10 days ago
15 Aug, 09:40
0.8
6 km West of Sansepolcro
30 km South-West · 10 km
10 days ago
14 Aug, 21:07
0.5
5 km West of Sansepolcro
29 km South-West · 11 km
12 days ago
13 Aug, 02:58
0.8
5 km West of Sansepolcro
29 km South-West · 10 km
12 days ago
12 Aug, 21:45
0.9
5 km West of Sansepolcro
29 km South-West · 11 km
12 days ago
12 Aug, 20:43

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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