All earthquakes
4.5
moderate
EARTHQUAKE DETAILS

1 km West of Trentinara

6 months ago · 21 Feb, 01:28

A moderate earthquake, felt by people in the area. Being deep, it is felt less at the surface.

No. 10 of the year in ItalyStronger than 99% of Italian events in the past yearNo. 3 of the year in CampaniaThe strongest of the past 12 months within 50 km

Where

1 km West of TrentinaraEarthquakes in the province of SalernoEarthquakes in Campania

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

3 events
Magnitude:lightweakmoderatestrong

The energy released

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

85tof TNT equivalent
355 lightning bolts
M3
×178 the energy of a magnitude 3 earthquake
M4this quakeM6

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 ≈ 95 s

Animation sped up ~18× compared to reality.

  • Battipaglia
    25 km from the epicentre
    first tremor in ~55 s
    main shaking in ~93 s
  • Salerno
    41 km from the epicentre
    first tremor in ~55 s
    main shaking in ~94 s
  • Cava de' Tirreni
    49 km from the epicentre
    first tremor in ~55 s
    main shaking in ~94 s
  • Scafati
    63 km from the epicentre
    first tremor in ~55 s
    main shaking in ~95 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

326 km
deep
37 times the height of Mount Everest

Being deep, it is felt less at the surface.

deeper than the area average (~15 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?

Isolated quake

In the 30 days around this event no other quakes were recorded within 30 km: a one-off episode, very common in Italy.

Activity in the area right now (30 km radius)
0
last 24 hours
1
last 7 days
3
last 30 days
1 before1 after
this quake
Strongest of the sequence2.0

How often does it happen here?

It is the first magnitude ≥ 4.5 earthquake recorded within 50 km since 2014, the start of our archive.

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.

15616.7
Vallo di Diano earthquake
19 August 1561 · 38 km from here
X-XICatastrophic: very few buildings remain standing; landslides and ground cracks.
15616.3
Vallo di Diano earthquake
31 July 1561 · 36 km from here
IX-XCompletely destructive: most buildings are destroyed.
14666.0
Irpinia-Basilicata earthquake
15 January 1466 · 45 km from here
VIII-IXDestructive: many buildings partly or fully collapse.
18535.6
Irpinia earthquake
9 April 1853 · 47 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

Irpinia-Agri Valley

The epicentre lies about 38 km from Irpinia-Agri Valley, one of the seismic structures mapped by INGV geologists.

estimated maximum magnitude 6.8between 1 and 14 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

1.8
2 km East of Contursi Terme
30 km North-East · 17 km
7 months ago
29 Jan, 07:24
2.0
2 km West of Bellosguardo
14 km East · 15 km
5 months ago
21 Mar, 02:44

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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