All earthquakes
1.4
very light
EARTHQUAKE DETAILS

M1.4 earthquake · 2 km East of Salemi (TP)

6 years ago · 23 Sept 2020, 23:49

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

Stronger than 63% of Italian events in the past year

Where

2 km East of SalemiEarthquakes in the province of TrapaniEarthquakes in Sicilia

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

39 events
Magnitude:lightweakmoderatestrong

The energy released

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

1.9kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×251 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 ≈ 19 s

Animation sped up ~4× compared to reality.

  • Trapani
    32 km from the epicentre
    first tremor in ~6 s
    main shaking in ~10 s
  • Marsala
    33 km from the epicentre
    first tremor in ~6 s
    main shaking in ~11 s
  • Palermo
    54 km from the epicentre
    first tremor in ~10 s
    main shaking in ~16 s
  • Bagheria
    63 km from the epicentre
    first tremor in ~11 s
    main shaking in ~19 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?

Aftershock

It is an aftershock: it follows a stronger quake (M3.5, 6 years ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

3.5
The mainshock
3 km North of Salemi
6 years ago · 9 Sept 2020, 06:56
Activity in the area right now (30 km radius)
0
last 24 hours
0
last 7 days
4
last 30 days
14 before24 after
this quake
Strongest of the sequence3.5

How often does it happen here?

about every ~49 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 87 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.

19686.4
Valle del Belice earthquake
15 January 1968 · 13 km from here
XCompletely destructive: most buildings are destroyed.
19685.5
Valle del Belice earthquake
15 January 1968 · 7 km from here
19685.5
Valle del Belice earthquake
16 January 1968 · 13 km from here
VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
19685.4
Valle del Belice earthquake
15 January 1968 · 14 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

Mazara-Belice

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

estimated maximum magnitude 6.1between 2 and 6 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

0.7
2 km North-East of Salemi
1 km North · 19 km
6 years ago
24 Sept 2020, 00:05
1.1
3 km South-West of Vita
4 km North-West · 12 km
6 years ago
23 Sept 2020, 23:22
0.9
2 km South of Vita
3 km North-West · 18 km
6 years ago
23 Sept 2020, 23:04
3.1
3 km South-West of Vita
4 km North-West · 12 km
6 years ago
23 Sept 2020, 22:50
1.2
2 km South of Salemi
3 km South-West · 14 km
6 years ago
24 Sept 2020, 03:07
1.2
1 km North-West of Salemi
2 km West · 9 km
6 years ago
25 Sept 2020, 00:53
1.6
2 km West of Vita
6 km North-West · 12 km
6 years ago
25 Sept 2020, 13:56
2.5
3 km North-West of Salemi
4 km North-West · 11 km
6 years ago
26 Sept 2020, 14:34
2.1
1 km North-West of Salemi
2 km West · 10 km
6 years ago
26 Sept 2020, 21:44
1.9
2 km South-West of Vita
5 km North-West · 12 km
6 years ago
26 Sept 2020, 22:32

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).