Proceedings of the International Symposium on Engineering Lessons Learned fromthe 2011 Great East Japan Earthquake, March 1-4, 2012, Tokyo, JapanA NEW TSUNAMI INTENSITY SCALEPROPOSED AFTER THE TSUNAMI OF
11 MARCH 2011, JAPANEfthymis LEKKAS1, Emmanuel ANDREADAKIS2, Irene KOSTAKI3, Eleni KAPOURANI4
1

Professor, Department of Geology and Geoenvironment, National and Kapodistrian University ofAthens, Athens, Greece, elekkas@geol.uoa.gr
2MSc, DrS, Department of Geology and Geoenvironment, National and Kapodistrian University ofAthens, Athens, Greece, eandreadk@geol.uoa.gr
3MSc, Department of Geology and Geoenvironment, National and Kapodistrian University of Athens,
Athens, Greece, kostakirene@gmail.com
4MSc, Department of Geology and Geoenvironment, National and Kapodistrian University of Athens,
Athens, Greece, elkap@geol.uoa.gr

ABSTRACT: The tsunami events caused by mega-earthquakes in the Indian Ocean (9.0,
12-26-04) and NE Japan (9.0, 03-11-11) had dramatic impact over extended areas andvarious distances from the source area, providing a huge amount of data, during
unprecedented situations. The records of magnitude and grade of impact allowed a more
precise specification of a more objective, 12-grade intensity scale of tsunamis, covering afull range of intensities, situations and environments. The proposed scale is based on 6
groups of criteria linking quantities, impact on all environments and human response.
Key Words: new scale, tsunami, intensity

INTRODUCTION
Tsunamis have occurred many times in both historical and recent times, as a result of great marine
earthquakes, volcanic eruptions or marine landslides. Many of these events have caused great damages
along coastal areas, as well as a great number of victims. In the historical times (before instrumental
observations) great events were recorded, such as for example the tsunami in the Mediterranean during
the eruption of Santorini (17th century BC), the tsunami of Lisbon (18th century) or the Krakatau
eruption (19th century).
In recent times, before 2004, a series of relatively minor – in the global scale - events haveoccurred, for instance the Hawaii tsunami (1940), the Alaska tsunami (1961) and the Chile tsunami(1964). These events have occurred in rather underdeveloped and/or sparsely inhabited areas, and theimpact on structures, infrastructure and people was not comparable to the more recent tsunami
disasters.
On the contrary, the Indian Ocean tsunami of 2004 caused by the 9.1 earthquake and the 2011
tsunami in Japan caused by the 9.0 earthquake were two global scale catastrophic events which openeda new era in the study of these phenomena in all their dimensions, due to the fact that for the first time
it was possible to observe, monitor and record all aspects frame by frame.

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Both tsunami events stroke wide geographical areas corresponding to under development urban
areas or developed areas with structures of any kind, rural areas with no residential cover, touristic
areas, industrial zones, developed infrastructure, port facility areas, areas protected against tsunami
waves, port constructions, etc.
Both tsunamis’ large scale effects and event study give us the opportunity to outline a more
complete picture for the disasters themselves as well as to conclude to a more accurate assessment of
the factors responsible for the disasters’ occurrence. The two big events offer an amount of evidence,
not present for past events, regarding the vulnerability of systems, resulting to a more accurate picturewith a great extent of the type and grade of disasters. In addition, data from great contemporary (e.g.
Maule, Chile 2010) and historical events (Santorini Island, Greece ~1464 B.C., Lisbon, Portugal 1755)
were taken into account.
The structure of the new tsunami intensity scale is based on 6 categories of criteria:a.
Physical quantities of the phenomenon itself, such as tsunami height, inundation depth, theextent of inundated areas, tsunami runup, etc. (JAFFE et al. 2006, LEKKAS et al. 2011a,
2011b).
b.
Impact on human environment, especially on human perception, but also on human behaviour reaction and human loss (ANDREADAKIS et al, 2011).
c.
Effects in mobile objects, such as vessels, boats, heavy objects, cars and means of transport(BRUCE et al. 2006, LEKKAS et al. 2011a, RAI et al. 2006).
d.
Impact on infrastructure, especially on offshore constructions, anti-erosion and anti-tsunami sea
walls, port constructions, onshore infrastructure, lifelines, port structures and equipment such as
cranes, tanks etc and industrial installations.
e.
Geoenvironmental effects (ANDREADAKIS et al. 2011, BRUCE et al. 2006, PARCHARIDIS
et al. 2005). In order to classify geoenvironmental effects, ESI2007 scale (MICHETTI et al. 2007)
was used. Both 12 grade EMS1998 and ESI2007 scales complete one another and linkcontemporary and historical earthquakes (LEKKAS, 2010) as well as earthquake effects that are
observed in completely different environments, eg: urban, semi-urban etc (LEKKAS 2010,
PAPANIKOLAOU et al. 2009). Some aspects of ESI2007 were used in this particular criteria
category, such as uplift - subsidence, morphological alterations, material transport, effects ontrees etc, whereas other elements were transferred to physical quantities category of criteria (acategory) as tsunami wave features for example.
f.
Effects in structured environment (GHOBARAH et al. 2005, LEKKAS et al. 2005, LEKKAS etal. 2011a, SAATCIOGLOU et al. 2006a, SAATCIOGLOU et al. 2006b, SCAWTHORN et al.
2006) EMS1998 scale (GRÜNTHAL et al. 1998) were used as a basis, in order to grade effects instructured environment. EMS1998 is a 12-grade scale referring to earthquake effects in several
structure types, in particular at: (i) Masonry type, (ii) Reinforced concrete type, (iii) Steel typeand (iv) Timber type. Additionally, classification damage is referred (Grade 1-5) in any structure
type. The type and grade of damage recorded as earthquake effects were adjusted to the damage
observed at the 2 great tsunami events of 2004 and 2011, where a really great number of cases ofdamage in every building type were observed. In addition, at some cases, vulnerability grading
was altered. For example, vulnerability of steel type structures was downgraded, as thisparticular type was proved to be particularly vulnerable to tsunami risk, as opposed to seismic
risk. Likewise, vulnerability grade of wooden structures was altered as well. The final valuationof the intensity levels follows the same methodology as EMS1998, using 3 definition levels ofquantity, few - many - most.

DESCRIPTION OF THE NEW SCALE
For every grade, the six categories of criteria are described accordingly (a to f):a.
Quantities of the phenomenon (wave height, inundation, runup, etc)b.
Impact on human environment (human perception, reaction and behavior in general)

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c.
d.
e.
f.

Impact on moving objects (small vessels, boats, heavy objects, cars, etc)
Impact on infrastructure (marine installations, anti-erosion works, ports, industry, etc)
Impact on geoenvironment, on the basis of the 12-grade ESI2007 (uplift and subsidence,morphological alterations, debris transport and deposition are taken into account)Impact on urban environment (all sorts of structures) on the basis of the EMS1998 scaleclassification.

Fig. 1 Total destruction, deformation and movement of steel structures in Onagawa town, Japan 2011
(Vulnerability Class C, Grade 5) (Intensity: XII).

Fig. 2 Runup evaluation (about 29m) in Onagawa area, Japan 2011 (Intensity: XII).

485

486

Tsunami height ofseveral cm to dm(0.5m). Limited
onshore areas
inundated.

Tsunami height ofsome dm (<1m).
Small onshore areas
are flooded.

V

VI

No effectIII

No effect

Many small vessels are
washed out violently or
collide with each otheror are overturned along
the shoreline. Cars are
uplifted and moved.

Marginal turbulence at coastal
sediments.

No effect

No effect

No effect

No effect

No effecte. Environment

Damage of grade 1 is sustained bymany buildings of vulnerability
class A and B; a few of class A
and B suffer damage of grade 2; afew of class C suffer damage of
grade 1

Damage of grade 1 to a few
buildings of vulnerability class A
and B

No damage

No damage

No damage

No damagef. Structures

StrongMany people panicand run for higher
ground.

No effect

No effect

No effect

No effect

No effectd. Infrastructure

Largely observed

Many small vessels get
washed on the shore
and many offshore
collide with each other.

Some small vessels
wiggle or move towards
the coast.

No effect

No effect

No effectc. Impact on mobile
objects

Weak

Tsunami height of afew cm.

No effect

II

Felt only by few
people on board
small vessels. Not
being noticed
onshore.
Felt only by many
people on board on
small vessels.
Being noticed by afew people
onshore.
Felt only by all
people on board on
small vessels. Felt
only by few people
on board on large
vessels and by
many people
onshore.
Felt by all on
board on big
vessels and people
onshore. Somepeople panic andrun for higher
ground.

Not felt, evenunder the mostfavorable
circumstancesb. Impact on
human

Slightly felt

IV

No effectIa. Quantities

Table 1 The New Tsunami Intensity Scale

Not felt
Slightly
damaging

VIII

Many people are
washed away.

All people runfor higher
ground. Many
are washedaway.

Tsunami heighthigher than 2m.
Limited onshore
areas are flooded.
Limited inundation
along coastline.

VII

IX

All people panicand run forhigher ground.

Tsunami height
usually higher than
1m . Small onshore
areas are flooded.

Tsunami height ofa few m (<5).
Wide areas areinundated along
the shoreline.
Tsunami runup ofsome m, whereas
inundation depth
reaches some
hundreds of m,depending oncoastalmorphology.

b. Impact on
human

a. Quantities

Many makeshiftfacilities along thecoastline are washedaway.

Many small vessels
suffer damage. Bigger
vessels are washed out
or collide with eachother. Heavy objects are
moved. Cars are washedaway.

Most makeshiftfacilities along thecoastline are washedaway. Little damage on
offshore backfilling.

Few makeshift facilities
on coastline are washedaway.

Many small vessels
suffer damage. Bigger
vessels are shaken
violently or collide witheach other. All cars arecarried away.

Depending on the topography andthe kind of coastal formations,limited coastal profile changes witherosion and material deposition
takes place. Garbage - debris
deposition along the shoreline.
Unrooting of bushes and some trees.

Erosion and garbage - debris along
the shoreline. Some bushes or trees
are unrooted and get carried away insmall distance.

Garbage - debris at parts of theshoreline. Limited erosion deposition of sand and pebble atcoastal areas.

e. Environment

487

Many buildings of vulnerability
class A sustain damage of grade 5.
Many buildings of vulnerability
class B suffer damage of grade 4; afew of grade 5. Many buildings ofvulnerability class C suffer
damage of grade 3; a few of grade
4. Many buildings of vulnerability
class D suffer damage of grade 2;
a few of grade 3. A few buildingsof vulnerability class E sustain
damage of grade 2.

Many buildings of vulnerability
class A suffer damage of grade 3;
a few of grade 4. Many buildingsof vulnerability class B suffer
damage of grade 2; a few of grade
3. A few buildings of vulnerability
class C sustain damage of grade 2.
A few buildings of vulnerability
class D sustain damage of grade 1.
Many buildings of vulnerability
class A suffer damage of grade 4;
a few of grade 5. Many buildingsof vulnerability class B suffer
damage of grade 3; a few of grade
4. Many buildings of vulnerability
class C suffer damage of grade 2; afew of grade 3. A few buildings ofvulnerability class D sustain
damage of grade 2.

f. Structures

Heavily damaging

Most vessels aredestroyed or sunk.
Many bigger vessels are
washed out and someare destroyed. Cars arebeing washed away.
Fires break along theshore.

d. Infrastructure

c. Impact on mobile
objects

Damaging
Destructive

Generalpanic. Most
people are
washed away.

Extensive
human loss.

Extended
human loss inwide areas.

Tsunami height ofmany m (<7). Tsunami
runup reaches orexceeds 10 m, whereas
inundation depth
reaches some hundreds
of m, depending oncoastal morphology.

Tsunami height ofmany m (<10m).
Tsunami runup exceeds
15 m, whereas
inundation depth
exceeds 1km,
depending on coastal
morphology.

Tsunami heightexceeds 10m. Runup
reaches many tens of mand inundation some
km. Areas of sometens km² areinundated.

XI

XII

X

b. Impacton humana. Quantities

488

Depending on the profile of offshore
and onshore area and probable upliftor subsidence, extended changes atthe coastal profile take place in wide
areas, due to erosion deposition anddeep erosion. Great changes oncoastline topography. Almost all trees
are unrooted and washed away. Big
boulders are washed away on great
distance. Massive pollution from oiland chemicals. Extensive fires break.

Boats are moved inhigh altitude. Cars,
trains etc are washedaway or destroyed.

All buildings of vulnerability class
A, B and practically all ofvulnerability class C are destroyed.
Most buildings of vulnerability
class D, E and F are destroyed.
The earthquake effects havereached the maximum conceivableeffects.

Depending on the profile of offshore
and onshore area and probable upliftor subsidence, changes at the coastal
profile take place due to erosion
deposition and deep erosion. Many
trees are unrooted and washed away,
small boulders are washed away.
Great pollution from oil andchemicals. Many fires break.

Extensive fires break.
Heavy objects are
washed away.
Extensive erosion.
Boats are washed off
for hundreds of monshore. Most cars
are washed away or
destroyed.

Devastating

Great damage in all port
works such as jetties,
marine breakwaters, port
facilities, cranes, onshore
lifelines. Riprap blocks aredetached and moved ingreat distances.

Most buildings of vulnerability
class B sustain damage of grade 5.
Most buildings of vulnerability
class C suffer damage of grade 4;
many of grade 5. Many buildingsof vulnerability class D suffer
damage of grade 4; a few of grade
5. Many buildings of vulnerability
class E suffer damage of grade 3; afew of grade 4. Many buildings ofvulnerability class F suffer damageof grade 2; a few of grade 3.

Breakwaters are damaged.
Failures at antierosional
works on the shoreline.
Damage on the roads near
the coastline. Greatdamage at onshore
lifelines. Damage on
cranes and other port
facilities. Tanks on port
facilities are moved. Raillines suffer damage. Many
riprap boulders aredetached and moved.
Some industrial facilities
are damaged.

Most buildings of vulnerability
class A sustain damage of grade 5.
Many buildings of vulnerability
class B sustain damage of grade 5.
Many buildings of vulnerability
class C suffer damage of grade 4; afew of grade 5. Many buildings ofvulnerability class D suffer
damage of grade 3; a few of grade
4. Many buildings of vulnerability
class E suffer damage of grade 2; afew of grade 3. A few buildings ofvulnerability class F sustain
damage of grade 2.

f. Structures

Depending on the profile of offshore
and onshore area, notable changes atthe coastal profile take place due toerosion and deposition. Trees areunrooted and washed away, smallboulders move. Extensive pollution
from oil and chemicals. Fires break.

e. Environment

Few damage on quays andport facilities. Damage on
objects at port facilities.
Small failures onantierrosional works on
the shoreline.

d. Infrastructure

Most big vessels are
washed out and many
are destroyed due toimpact on the
shoreline andbuildings. Cars
overturn and are
washed away.

c. Impact on
mobile objects

Very destructive
Completely devastatingFig. 3 Damaged coastal infrastructures in Batong, Thailand 2004 (Intensity: IX) and in Ogatsu, Japan
2011 (Intensity: XII).

Fig. 4 Tsunami induced transport and deposition of vessels in Thailand 2004 (Intensity: VIII-IX) andJapan 2011 (Intensity: XI-XII).
CONCLUSIONS
The main characteristics of the new tsunami intensity scale are:
1. The scale is based on 6 different criteria, more than any other existing scale (e.g.
Papadopoulos & Imamura 2009) and offers horizontal correlation between criteria in every
intensity grade.
2. There is a gradual increase of the intensity grades, which is observable in all 6 criteria
categories with clear boundaries between grades, at the same time.
3. Quantities are easily measured. Objective criteria are more than subjective criteria.
4. Evidence and grading is based at fieldwork data and particular damage types and not intheoretical data. In addition, photographic material documentation is available.
5. The new intensity scale is fully compatible with EMS1998 and ESI2007 seismic intensity scales.
6. Covers a wide span of land use type areas, such as agricultural, natural, ports, and a variety ofdifferent infrastructure and protection facilities/works.
7. Application of the scale and area microzonation in smaller areas is easier via the use of remotesensing techniques.
8. A 12-grade scale is more accurate and does not saturate, as 6-grade scales do.

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Fig. 5 Satellite imagery before and after the 2011 Tsunami, showing the effects on coastal areas, about
5km of Miyako town, in Onatsube area. Inundation was estimated at 750m and Runup at 37m.
Damage in port facilities, infrastructure, houses and industrial facilities etc., are visible, as well as
effects in natural environment (Intensity: XII).
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