All earthquakes
1.2
very light
EARTHQUAKE DETAILS

3 km East of Castelnuovo di Val di Cecina

137 months ago · 20 Mar, 20:01

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 47% of Italian events in the past year

Where

3 km East of Castelnuovo di Val di CecinaEarthquakes in the province of PisaEarthquakes in Toscana

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

14 events
Magnitude:lightweakmoderatestrong

The energy released

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

1.0kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×501 its energy
M0this quakeM2

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 ≈ 21 s

Animation sped up ~4× compared to reality.

  • Siena
    30 km from the epicentre
    first tremor in ~5 s
    main shaking in ~9 s
  • Firenze
    66 km from the epicentre
    first tremor in ~11 s
    main shaking in ~19 s
  • Grosseto
    67 km from the epicentre
    first tremor in ~11 s
    main shaking in ~19 s
  • Pisa
    71 km from the epicentre
    first tremor in ~12 s
    main shaking in ~21 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
shallow
1.1 times the height of Mount Everest

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

in line with the area average (~9 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: 136 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
2 km South-East of Pomarance
136 months ago · 6 Apr, 18:37
Activity in the area right now (30 km radius)
0
last 24 hours
1
last 7 days
8
last 30 days
3 before10 after
this quake
Strongest of the sequence1.8

How often does it happen here?

about every ~14 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 298 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.

18466.0
Colline Pisane earthquake
14 August 1846 · 42 km from here
XCompletely destructive: most buildings are destroyed.
14145.7
Colline Metallifere earthquake
7 August 1414 · 14 km from here
VII-VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
19095.3
Crete Senesi earthquake
25 August 1909 · 37 km from here
VII-VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
17265.3
Crete Senesi earthquake
19 April 1726 · 45 km from here

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

The closest seismic structure

Livorno Hills

The epicentre lies about 42 km from Livorno Hills, one of the seismic structures mapped by INGV geologists.

estimated maximum magnitude 6.2between 1 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

1.3
5 km East of Monterotondo Marittimo
12 km South-West · 8 km
137 months ago
19 Mar, 21:35
1.6
136 months ago
1 Apr, 20:21
1.4
3 km North-East of Montieri
11 km South-East · 9 km
136 months ago
2 Apr, 06:56
1.4
3 km North-West of Monteriggioni
26 km North-East · 7 km
136 months ago
2 Apr, 08:55
1.2
136 months ago
6 Apr, 00:39
1.8
136 months ago
6 Apr, 18:37
1.6
1 km North of Montieri
12 km South-East · 9 km
136 months ago
9 Apr, 01:27
1.8
137 months ago
28 Feb, 15:36
1.7
136 months ago
10 Apr, 13:05
0.7
9 km South-West of Chiusdino
16 km South-East · 7 km
136 months ago
15 Apr, 07:24

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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