Jordskjelvstyrken på
richterskalaen
| Virkning
| Antall pr. år
|
Mindre enn 3,0
(ikke merkbart)
| Registreres bare på instrumenter.
| 900 000
|
3,0 - 5,4
(lett til sterkt)
| Merkbart for mennesker. Bare mindre skader.
| 30 000
|
5,5 - 6,0
(meget sterkt)
| Skader på byggninger.
| 500
|
6,1 - 6,9
(voldsomt)
| Bygninger styrter sammen. Store ødeleggelser.
| 100
|
7,0 - 7,9
(ødeleggende)
| Få bygninger står igjen. Jorda sprekker. Jordskred.
| 20
|
Større enn 8,0
(katastrofalt)
| Total ødeleggelse forekommer.
| Hvert 5. 10. år*)
|
Tabellen er hentet fra :http://www.pvv.ntnu.no/~dennisgl/semester/naturfag/skjelv/all.html,
en glimrende semesteroppgave om jordskjelv og vulkaner.
*) Jordskjelv > 8,0: 1989=1 1993=1 1994=2 1995=3
1996=1
Et jordskjelv som måler 6 på Richets
Skala er ti ganger så kraftig som et på 5. Et skjelv på
5,2 vil være 2 ganger så kraftig som et på 5. Richters
skala
er imidlertid ikke god nok efter dagens målestokk, og blir delvis
erstattet innen seismologien med en nyere.
Se EMS nedenfor
---------------------------------------------------------
Richters scale
Value on the scale
|
Result
| Numbers per year
|
Less than 3,0
(not felt)
| Registered only by instruments
| 900 000
|
3,0 - 5,4
(middle to strong)
| To be felt by people. Only minor damage..
| 30 000
|
5,5 - 6,0
(very strong)
| Damages on buildings
| 500
|
6,1 - 6,9
(violent)
| Buildings collapses. Larde damages.
| 100
|
7,0 - 7,9
(damaging)
| Few buildings left. Earth opens. Lavines.
| 20
|
Større enn 8,0
(catastrophic)
| Total destruction happens
| every 5 to 10. year*)
|
Table
from
:http://www.pvv.ntnu.no/~dennisgl/semester/naturfag/skjelv/all.html,
*) Quakes > 8,0: 1989=1 1993=1 1994=2
1995=3 1996=1
A quake measuring 6 onRichets Scale is 10
times stronger than one at 5.
A quake of 5.2 will be twice (or 2 times) as strong as one
at 5.
However, Richters scale is not valuable in to days world,
and has been more or less outdated (?)
See EMS below.
|
and another one from USGS Survey
Short form of the EMS-98
The
short form of the European Macroseismic Scale, abstracted from the
Core Part, is intended to give a very simplified and generalized
view of the EM Scale.
It can, e.g., be used for educational purposes. This short form
is not suitable for intensity assignments.
EMS intensity |
Definition |
Description
of typical observed effects
(abstracted)
|
I |
Not felt |
Not felt. |
II |
Scarcely felt |
Felt only by very few individual
people at rest in houses. |
III |
Weak |
Felt indoors by a few people.
People at rest feel a swaying or light trembling. |
IV |
Largely observed |
Felt indoors by many people,
outdoors by very few. A few people are awakened. Windows, doors
and dishes rattle. |
V |
Strong |
Felt indoors by most, outdoors
by few. Many sleeping people awake. A few are frightened. Buildings
tremble throughout. Hanging objects swing considerably. Small
objects are shifted. Doors and windows swing open or shut. |
VI |
Slightly damaging |
Many people are frightened and
run outdoors. Some objects fall. Many houses suffer slight non-structural
damage like hair-line cracks and fall of small pieces of plaster. |
VII |
Damaging |
Most people are frightened and
run outdoors. Furniture is shifted and objects fall from shelves
in large numbers. Many well built ordinary buildings suffer
moderate damage: small cracks in walls, fall of plaster, parts
of chimneys fall down; older buildings may show large cracks
in walls and failure of fill-in walls. |
VIII |
Heavily damaging |
Many people find it difficult
to stand. Many houses have large cracks in walls. A few well
built ordinary buildings show serious failure of walls, while
weak older structures may collapse. |
IX |
Destructive |
General panic. Many weak constructions
collapse. Even well built ordinary buildings show very heavy
damage: serious failure of walls and partial structural failure. |
X |
Very destructive |
Many ordinary well built buildings
collapse. |
XI |
Devastating |
Most ordinary well built buildings
collapse, even some with good earthquake resistant design are
destroyed. |
XII |
Completely devastating |
Almost all buildings are destroyed. |
|