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2.5
light
EARTHQUAKE DETAILS

M2.5 earthquake · 4 km North-East of Rimini (RN)

10 years ago · 21 Nov 2015, 07:51

A light earthquake, rarely felt by people. Being deep, it is felt less at the surface.

Stronger than 95% of Italian events in the past year

Where

4 km North-East of RiminiEarthquakes in the province of RiminiEarthquakes in Emilia-Romagna

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.

85kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×5.6 its energy
M2this quakeM4

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 ≈ 16 s

Animation sped up ~3× compared to reality.

  • Rimini
    4 km from the epicentre
    first tremor in ~6 s
    main shaking in ~11 s
  • Cesena
    28 km from the epicentre
    first tremor in ~8 s
    main shaking in ~13 s
  • Pesaro
    31 km from the epicentre
    first tremor in ~8 s
    main shaking in ~14 s
  • Fano
    43 km from the epicentre
    first tremor in ~10 s
    main shaking in ~16 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

37 km
deep
4.2 times the height of Mount Everest

Being deep, it is felt less at the surface.

deeper than the area average (~17 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 (M3.5, 10 years ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

3.5
The mainshock
2 km South-West of Montescudo-Monte Colombo
10 years ago · 11 Nov 2015, 19:13
Activity in the area right now (30 km radius)
0
last 24 hours
1
last 7 days
4
last 30 days
11 before2 after
this quake
Strongest of the sequence3.5

How often does it happen here?

about every ~44 days

Within 50 km of this epicentre, a magnitude ≥ 2.5 earthquake has occurred on average this often: 97 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.

19165.8
Riminese earthquake
16 August 1916 · 15 km from here
VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
19165.8
Riminese earthquake
17 May 1916 · 17 km from here
VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
18755.7
Costa romagnola earthquake
17 March 1875 · 19 km from here
VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
14835.7
Romagna earthquake
11 August 1483 · 29 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

Riminese onshore

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

estimated maximum magnitude 7.0between 2 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

1.8
3 km East of Mercatino Conca
20 km South · 48 km
10 years ago
14 Nov 2015, 08:54
1.4
10 years ago
14 Nov 2015, 04:45
1.5
1 km North of Sassofeltrio
18 km South · 39 km
10 years ago
11 Nov 2015, 20:18
3.5
10 years ago
11 Nov 2015, 19:13
0.9
1 km West of Montecopiolo
29 km South-West · 19 km
10 years ago
11 Nov 2015, 18:05
1.3
1 km South-West of Montecopiolo
29 km South-West · 17 km
10 years ago
11 Nov 2015, 11:42
0.9
2 km North-East of Montecopiolo
27 km South-West · 16 km
10 years ago
11 Nov 2015, 08:10
1.0
0 km North-East of Montecopiolo
28 km South-West · 21 km
10 years ago
11 Nov 2015, 05:40
0.8
0 km North-West of Montecopiolo
28 km South-West · 19 km
10 years ago
11 Nov 2015, 03:18
1.2
4 km South-West of San Leo
25 km South-West · 18 km
10 years ago
11 Nov 2015, 00:01

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).