All earthquakes
1.9
very light
EARTHQUAKE DETAILS

2 km North-West of Bolano

38 months ago · 24 Jul, 09:20

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

Stronger than 85% of Italian events in the past year

Where

2 km North-West of BolanoEarthquakes in the province of La SpeziaEarthquakes in Liguria

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

15 events
Magnitude:lightweakmoderatestrong

The energy released

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

11kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×45 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 ≈ 14 s

Animation sped up ~3× compared to reality.

  • La Spezia
    12 km from the epicentre
    first tremor in ~3 s
    main shaking in ~4 s
  • Carrara
    22 km from the epicentre
    first tremor in ~4 s
    main shaking in ~7 s
  • Massa
    28 km from the epicentre
    first tremor in ~5 s
    main shaking in ~9 s
  • Viareggio
    49 km from the epicentre
    first tremor in ~8 s
    main shaking in ~14 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

10 km
medium depth
1.1 times the height of Mount Everest

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

in line with the area average (~12 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: 37 months ago the same area had a stronger quake (M2.2). This can only be said after the fact — it was not predictable beforehand.

2.2
The mainshock
4 km East of Aulla
37 months ago · 19 Aug, 17:07
Activity in the area right now (30 km radius)
0
last 24 hours
2
last 7 days
7
last 30 days
6 before8 after
this quake
Strongest of the sequence2.2

How often does it happen here?

about every ~13 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 330 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.

19206.5
Garfagnana earthquake
7 September 1920 · 32 km from here
XCompletely destructive: most buildings are destroyed.
18346.0
Val di Taro-Lunigiana earthquake
14 February 1834 · 25 km from here
IXDestructive: many buildings partly or fully collapse.
18375.9
Lunigiana earthquake
11 April 1837 · 25 km from here
XCompletely destructive: most buildings are destroyed.
19205.6
Garfagnana earthquake
6 September 1920 · 33 km from here

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

The closest seismic structure

Lunigiana

The epicentre lies about 6 km from Lunigiana, one of the seismic structures mapped by INGV geologists.

estimated maximum magnitude 7.0between 1 and 10 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

1.3
2 km South-West of Licciana Nardi
16 km North-East · 10 km
38 months ago
22 Jul, 22:32
1.0
1 km South-West of Bolano
3 km South-East · 11 km
37 months ago
30 Jul, 05:04
1.1
6 km South of Ameglia
23 km South-East · 8 km
37 months ago
30 Jul, 08:23
1.7
2 km East of Albareto
30 km North-West · 7 km
38 months ago
3 Jul, 04:06
1.3
38 months ago
2 Jul, 01:43
0.9
2 km South-East of Comano
24 km East · 13 km
37 months ago
17 Aug, 08:36
0.9
3 km North-East of Fosdinovo
16 km East · 10 km
37 months ago
18 Aug, 21:25
1.5
5 km East of Aulla
13 km East · 7 km
37 months ago
18 Aug, 22:07
1.4
1 km West of Sarzana
14 km South-East · 9 km
39 months ago
28 Jun, 19:40
2.2
4 km East of Aulla
13 km East · 8 km
37 months ago
19 Aug, 17:07

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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