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2.0
light
EARTHQUAKE DETAILS

2 km South-East of Offida

73 months ago · 28 Aug, 13:02

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

Stronger than 88% of Italian events in the past year

Where

2 km South-East of OffidaEarthquakes in the province of Ascoli PicenoEarthquakes in Marche

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

42 events
Magnitude:lightweakmoderatestrong

The energy released

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

15kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×32 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 ≈ 22 s

Animation sped up ~4× compared to reality.

  • Teramo
    30 km from the epicentre
    first tremor in ~7 s
    main shaking in ~12 s
  • Montesilvano
    59 km from the epicentre
    first tremor in ~11 s
    main shaking in ~19 s
  • Pescara
    65 km from the epicentre
    first tremor in ~12 s
    main shaking in ~20 s
  • Chieti
    72 km from the epicentre
    first tremor in ~13 s
    main shaking in ~22 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

29 km
medium depth
3.3 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 (M3.0, 73 months ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

3.0
The mainshock
3 km South-West of Roccafluvione
73 months ago · 22 Aug, 12:50
Activity in the area right now (30 km radius)
0
last 24 hours
2
last 7 days
10
last 30 days
20 before21 after
this quake
Strongest of the sequence3.0

How often does it happen here?

about every ~1 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 6767 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.

20166.2
Monti della Laga earthquake
24 August 2016 · 48 km from here
XCompletely destructive: most buildings are destroyed.
18735.8
Appennino marchigiano earthquake
12 March 1873 · 44 km from here
IXDestructive: many buildings partly or fully collapse.
19505.7
Gran Sasso earthquake
5 September 1950 · 48 km from here
VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
19435.7
Ascolano earthquake
3 October 1943 · 9 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

Southern Marche

The epicentre sits above this source area: the deep structure where this area's earthquakes can originate.

estimated maximum magnitude 6.9between 4 and 11 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

2.6
73 months ago
2 Sept, 03:13
0.8
2 km North of Ascoli Piceno
21 km West · 19 km
73 months ago
2 Sept, 03:25
1.4
73 months ago
2 Sept, 03:33
2.6
1 km South-West of Offida
2 km West · 23 km
73 months ago
2 Sept, 08:43
1.6
73 months ago
2 Sept, 10:57
1.3
73 months ago
2 Sept, 11:19
1.8
1 km South of Offida
1 km West · 27 km
73 months ago
2 Sept, 15:18
1.4
73 months ago
2 Sept, 15:24
1.0
7 km East of Valle Castellana
25 km South-West · 18 km
73 months ago
23 Aug, 07:15
1.2
7 km East of Valle Castellana
24 km South-West · 17 km
73 months ago
23 Aug, 06:51

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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