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2.2
light
EARTHQUAKE DETAILS

11 km North of San Nicandro Garganico

114 months ago · 18 Apr, 07:30

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

Stronger than 92% of Italian events in the past year

Where

11 km North of San Nicandro GarganicoEarthquakes in the province of FoggiaEarthquakes in Puglia

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.

30kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×16 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 ≈ 23 s

Animation sped up ~4× compared to reality.

  • San Severo
    39 km from the epicentre
    first tremor in ~7 s
    main shaking in ~12 s
  • Manfredonia
    45 km from the epicentre
    first tremor in ~8 s
    main shaking in ~14 s
  • Foggia
    55 km from the epicentre
    first tremor in ~10 s
    main shaking in ~17 s
  • Cerignola
    79 km from the epicentre
    first tremor in ~14 s
    main shaking in ~23 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

20 km
medium depth
2.2 times the height of Mount Everest

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

in line with 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?

Foreshock

In hindsight it was a foreshock: 114 months ago the same area had a stronger quake (M3.9). This can only be said after the fact — it was not predictable beforehand.

3.9
The mainshock
4 km East of Cagnano Varano
114 months ago · 23 Apr, 06:25
Activity in the area right now (30 km radius)
0
last 24 hours
0
last 7 days
7
last 30 days
3 before10 after
this quake
Strongest of the sequence3.9

How often does it happen here?

about every ~8 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 531 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.

16466.7
Gargano earthquake
31 May 1646 · 36 km from here
XCompletely destructive: most buildings are destroyed.
16276.7
Capitanata earthquake
30 July 1627 · 29 km from here
XCompletely destructive: most buildings are destroyed.
16276.0
Capitanata earthquake
7 August 1627 · 28 km from here
IXDestructive: many buildings partly or fully collapse.
16576.0
Capitanata earthquake
29 January 1657 · 28 km from here
IX-XCompletely destructive: most buildings are destroyed.

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

The closest seismic structure

Tocco Casauria-Tremiti

The epicentre lies about 19 km from Tocco Casauria-Tremiti, one of the seismic structures mapped by INGV geologists.

estimated maximum magnitude 7.5between 11 and 20 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

2.1
4 km East of San Nicandro Garganico
12 km South-East · 7 km
114 months ago
21 Apr, 04:16
3.9
4 km East of Cagnano Varano
22 km South-East · 30 km
114 months ago
23 Apr, 06:25
0.8
1 km South-West of Cagnano Varano
18 km South-East · 25 km
114 months ago
24 Apr, 13:11
2.8
5 km West of Carpino
23 km East · 29 km
114 months ago
24 Apr, 13:48
1.7
6 km South-West of Carpino
28 km South-East · 21 km
113 months ago
2 May, 22:05
1.6
113 months ago
8 May, 19:19
2.2
113 months ago
8 May, 19:56
1.9
4 km West of Apricena
20 km South-West · 15 km
115 months ago
24 Mar, 17:17
1.5
115 months ago
23 Mar, 22:53
1.1
113 months ago
15 May, 04:50

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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