All earthquakes
1.8
very light
EARTHQUAKE DETAILS

M1.8 earthquake · 3 km West of Cupra Marittima (AP)

5 years ago · 31 Mar 2021, 06:17

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

Stronger than 82% of Italian events in the past year

Where

3 km West of Cupra MarittimaEarthquakes 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

11 events
Magnitude:lightweakmoderatestrong

The energy released

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

7.6kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×63 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 ≈ 21 s

Animation sped up ~4× compared to reality.

  • Teramo
    39 km from the epicentre
    first tremor in ~8 s
    main shaking in ~14 s
  • Montesilvano
    64 km from the epicentre
    first tremor in ~12 s
    main shaking in ~20 s
  • Pescara
    69 km from the epicentre
    first tremor in ~13 s
    main shaking in ~21 s
  • Ancona
    70 km from the epicentre
    first tremor in ~13 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

28 km
medium depth
3.2 times the height of Mount Everest

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

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?

Mainshock

It is the strongest quake of its sequence: so far it has been followed by 5 aftershocks within 30 km. Aftershocks tend to fade in number and strength over time.

Activity in the area right now (30 km radius)
0
last 24 hours
2
last 7 days
9
last 30 days
5 before5 after
this quake
Strongest of the sequence1.8

How often does it happen here?

about every ~3 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 1355 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.

18735.8
Appennino marchigiano earthquake
12 March 1873 · 47 km from here
IXDestructive: many buildings partly or fully collapse.
19435.7
Ascolano earthquake
3 October 1943 · 17 km from here
IXDestructive: many buildings partly or fully collapse.
19725.5
Marche meridionali earthquake
26 November 1972 · 29 km from here
VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
19515.3
Monti Sibillini earthquake
1 September 1951 · 42 km from here
VIIVery strong: hard to stand; chimneys and roof tiles fall, serious damage to weaker buildings.

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

The closest seismic structure

Southern Marche

The epicentre lies about 9 km from Southern Marche, one of the seismic structures mapped by INGV geologists.

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

1.3
5 years ago
31 Mar 2021, 06:22
1.3
2 km North-West of Cupra Marittima
3 km North-East · 27 km
5 years ago
26 Mar 2021, 02:24
1.4
2 km North of Falerone
30 km West · 21 km
5 years ago
25 Mar 2021, 21:37
1.2
5 years ago
25 Mar 2021, 18:09
1.2
0 km North-East of Falerone
29 km West · 22 km
5 years ago
25 Mar 2021, 04:03
1.6
4 km West of Cupra Marittima
1 km North-West · 24 km
5 years ago
24 Mar 2021, 12:03
1.1
1 km West of Montelparo
22 km West · 25 km
5 years ago
10 Apr 2021, 06:52
1.8
5 years ago
13 Apr 2021, 14:02
1.3
5 years ago
18 Apr 2021, 22:41
1.7
5 years ago
25 Apr 2021, 20:19

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).