All earthquakes
1.2
very light
EARTHQUAKE DETAILS

M1.2 earthquake · 9 km East of Riposto (CT)

11 years ago · 1 Aug 2015, 03:15

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

Stronger than 48% of Italian events in the past year

Where

9 km East of RipostoEarthquakes in the province of CataniaEarthquakes 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

23 events
Magnitude:lightweakmoderatestrong

The energy released

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

1.0kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×501 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 ≈ 18 s

Animation sped up ~3× compared to reality.

  • Acireale
    14 km from the epicentre
    first tremor in ~4 s
    main shaking in ~7 s
  • Catania
    34 km from the epicentre
    first tremor in ~7 s
    main shaking in ~11 s
  • Messina
    58 km from the epicentre
    first tremor in ~10 s
    main shaking in ~18 s
  • Reggio di Calabria
    58 km from the epicentre
    first tremor in ~10 s
    main shaking in ~18 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.

deeper than the area average (~13 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, 11 years ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

3.0
The mainshock
2 km North of Mascalucia
11 years ago · 15 Jul 2015, 18:29
Activity in the area right now (30 km radius)
0
last 24 hours
10
last 7 days
18
last 30 days
14 before8 after
this quake
Strongest of the sequence3.0

How often does it happen here?

about every ~2 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 2225 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.

18186.3
Catanese earthquake
20 February 1818 · 17 km from here
IX-XCompletely destructive: most buildings are destroyed.
19905.6
Sicilia sud-orientale earthquake
13 December 1990 · 45 km from here
VII-VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
17805.5
Sicilia nord-orientale earthquake
28 March 1780 · 19 km from here
VII-VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
18485.5
Golfo di Catania earthquake
11 January 1848 · 30 km from here
VIII-IXDestructive: many buildings partly or fully collapse.

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

The closest seismic structure

Gela-Catania

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

estimated maximum magnitude 7.1between 3 and 10 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

1.7
1 km East of Milo
16 km West · 11 km
11 years ago
6 Aug 2015, 07:08
1.2
7 km East of Sant'Alessio Siculo
28 km North-East · 9 km
11 years ago
7 Aug 2015, 06:21
2.1
11 years ago
8 Aug 2015, 18:17
1.4
11 years ago
12 Aug 2015, 05:45
1.5
11 km South of Moio Alcantara
27 km North-West · 30 km
11 years ago
12 Aug 2015, 05:56
1.4
11 years ago
20 Jul 2015, 15:31
1.7
8 km South of Moio Alcantara
26 km North-West · 5 km
11 years ago
19 Jul 2015, 11:16
1.7
11 years ago
16 Aug 2015, 20:39
1.8
4 km West of Sant'Alfio
24 km West · 6 km
11 years ago
16 Jul 2015, 08:40
1.3
8 km West of Sant'Alfio
27 km West · 11 km
11 years ago
16 Jul 2015, 07:19

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).