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7/25/2019 Landslide Investigation by Means of Photogrammetry
1/8
Photogrammetria - Elsevier Publishing Compan y, Amster dam - Printed in The Netherl ands
L A N D S L I D E I N V E S T I G A T I O N B Y M E A N S O F P H O T O G R A M M E T R Y
P. R. SALGUEIRO
International Training Centre for Aerial Survey, Delft The Netherlands)
Received February 2, 1965)
SUMMARY
L a r g e - s c a l e p h o t o g r a m m e t r i c s u r v e y h a s b e e n a p p l i e d t o i n v e s ti g a te a l a n d s li d e
i n a d e n s e l y p o p u l a t e d a r e a o f L a P a z , B o l iv i a . B y t h i s te c h n i q u e , t h e m a s s o f
t h e l a n d sl id e , t h e d i s t r i b u t io n a n d t h e e f f e c ts o f th e m o v e m e n t s o v e r t h e w h o l e
a r e a w e r e s t u d i e d . A s a r e s u l t , m e a n s a n d m e a s u r e s h a v e b e e n p r o p o s e d t o c o n t r o l
t h e l a n d s li d e a n d t o p r e v e n t f u r t h e r d e s t r u c t i v e e ff e c ts .
INTRODUCTION
L a n d s l i d e s a r e a p h e n o m e n o n o f e n g i n e e r i n g i m p o r t a n c e w h e n t h e y t a k e p l a c e i n
a r e a s w h e r e t h e r e i s a n a s s o c i a t io n w i t h p r o b l e m s o f s o ci a l, e c o n o m i c a n d t e c h n i c a l
n a t u r e , a s in t h e c a s e o f L a P a z c i t y , c a p i t a l o f B o l i v i a , s i t u a t e d i n t h e A n d e s a t
3 , 6 0 0 m a b o v e s e a le v e l i n a n a r r o w v a l le y o f t h e w e s t e r n C o r d i l l e ra a t t h e f o o t o f
t h e A n d e a n g r a n it ic o u t c r o p .
A l a nd s li d e s u ch a s h a s o c c u r r e d a t L a P a z is a c o m m o n p h e n o m e n o n
t h a t c o u l d h a p p e n i n m a n y p l a c es i n t h e w o r l d . T h e p u r p o s e o f t h is p a p e r i s t o
s h o w h o w p h o t o g r a m m e t r i c t e c h n i q u e s m i g h t b e u s e d a s a s t a n d a r d t o o l f o r s ci e n -
t if ic c o n t r o l a n d i n v e s t ig a t i o n in o r d e r t o e s t a b li s h p r e c a u t i o n a r y m e a s u r e s w h i c h
w o u l d m i n i m i z e t h e d e s tr u c t i v e e f fe c t s t h a t t a k e p l a c e i n p o p u l a t e d r e g i o n s o r i n
a r e a s o f i m p o r t a n t m a n - m a d e w o r k s d a m s , b r id g e s , h i g h w a y s , e t c. ).
PHOTOGRAMMETRIC INVESTIGATION
I n M a r c h 1 9 5 8 , o n e o f t h e l a r g e st la n d s li d e s t o o k p l a c e in t h e a r e a s h o w n i n t h e
s t e r e o s c o p ic m o d e l s o f F i g . 1 - 3 . F i g .1 is a p h o t o g r a p h t a k e n 2 y e a r s b e f o r e t h e
e v e n t , s c a le 1 : 1 2 , 0 0 0 1 9 5 6 ) . F i g . 2 w a s ta k e n 1 w e e k a f t e r t h e p h e n o m e n o n ,
s c al e 1 : 6 , 0 0 0 1 9 5 8 ) . F i g . 3 c o r r e s p o n d s t o a e r ia l p h o t o g r a p h y t a k e n 5 1/2 y e a r s
l a te r , s c a le 1 : 1 4 , 0 0 0 1 9 6 3 ) . A s i m p l e s t e r e o s c o p i c c o m p a r i s o n o f t h e m e n t i o n e d
f i g u r e s b r i n g s o u t i n t e r e s t i n g c o n c l u s i o n s t o t h e s u b j e c t u n d e r d i s c u s s i o n .
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10 8 P R SALGUEIRO
Fig.1. Stereoscopic model, befo re the landslide 1956).
Fig.2. Stereoscopic model, 1 w ee k after the landslide 1958).
T h e n a t u r e o f t h is i n v e s t i g a t io n i m p l i e s a h i g h l y a c c u r a t e t r e a t m e n t s i n c e d a t a
o f h i g h e s t a c c u r a c y w e r e d e s i r e d t o c o m p a r e m o r p h o l o g i c a l c h a n g e s i n p o s i t io n a s
w e l l a s i n h e i g h t . T h i s i n v e s t i g a t i o n w a s c o m p l e m e n t e d b y g e o l o g i c a l a n d f i r s t -
o r d e r l e v e li n g m e a s u r e m e n t s u s in g a W i ld N 3 .
T h e l a r g e - s c a l e a e r i a l p h o t o g r a p h y a n d t y p e o f a e r i a l c a m e r a w e r e a p p r o -
p r i a t e to t h e t y p e o f in v e s t ig a t io n . A W i l d R . C . 5 c a m e r a w i t h A v i o g o n l en s , t h e
Z e i s s c a m e r a w i t h P l e o g o n le n s a n d t h e F a i r c h i l d T . 1 2 c a m e r a w i th P l a n i g o n l e n s,
r e s p e c ti v e ly , w e r e e m p l o y e d . G l a s s p l a te s o f 6 m m t h i ck n e s s w h e r e u s e d o n t h e
u n i v e r s al p h o t o g r a m m e t r i c i n s t ru m e n t , a u t o g r a p h W i l d A 7 , a f t e r c a r e f u l a d j u s t m e n t .
Photograrnmetr a, 20 196 5) 107-114
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LANDSLIDE INVESTIGA TIONBY MEA NS OF PHOTOGRAMMETRY 109
C o n t r o l p o i n t s o f a f i r s t - o r d e r t r ia n g u l a t i o n n e t o f L a P a z c i t y w e r e u s e d a s
g r o u n d c o n t ro l . F i v e w e l l- d e f in e d c o n t r o l p o i n t s h a v e g i v e n a g o o d a c c u r a c y f o r
t h e p l o t ti n g a n d c o n t r o l f o r e a c h p a i r o f p h o t o g r a p h s , o b t a i n in g a m e a n s q u a r e
e r r o r i n p o s i t i o n o f c a . 0 .5 m a n d i n h e i g h t o f c a . 0 . 3 5 m i n th e m o d e l s . T h e c o n t r o l
w a s v e r y a c c u r a t e a n d t h e l a r g e s t d i s c r e p a n c y f o u n d w a s o f th e o r d e r o f 1 .0 m i n X
a n d Y . T h e g i v e n r e s u l ts i n d i c a te t h a t t h e w o r k c a r r i e d o u t o n t h e W i l d A 7 w a s o f
f i rs t q u a l i ty . T h e i n d i c a t e d m e a n s q u a r e e r r o r s i n p o s i t io n o f 0 . 5 m a n d i n h e i g h t
o f 0 . 3 5 m a r e fu l l y i n a c c o r d a n c e w i t h t h a t c a n b e e x p e c t e d f r o m t h e s e s m a l l - s c a l e
p h o t o g r a p h s . F r o m t he p h o t o g r a p h s 1 : 6 , 0 0 0 a b o u t h a lf t h es e va l ue s c o u l d be
e x p e c t e d .
U n d e r t h e c o n d i t i o n s o u t l i n e d a b o v e f o r p r e c i s i o n , th e t h r e e m o d e l s w e r e
p l o t t e d o n t h e W i l d A 7 a t t h e s c a l e 1 : 1 , 0 0 0 , s t a r t i n g w i t h t h e 1 9 5 8 m o d e l w h i c h
s e r v e d a s a b a s e t o d e l i n e a t e t h e e f f e c t s a n d s h a p e o f t h e l a n d s l i d e . I t w a s u s e d
a f t e r w a r d s a s a r e f e r e n c e f o r t h e 1 9 5 6 a n d t h e 1 9 6 3 p l o t t in g m o d e l s . A l t h o u g h t h e
s c a le s o f t h e a i r p h o t o g r a p h s a r e d i f f e r e n t a n d i n p a r t i c u l a r t h e s c a le s o f 1 9 5 6 a n d
1 9 6 3 a r e n o r m a l l y t o o s m a l l f o r r e s ti t u t io n i n a sc a l e 1 : 1 , 0 0 0 , t h i s m a p p i n g s c a l e
h a s b e e n a c c e p t e d i n o r d e r t o f a c i li ta t e t h e c o m p a r i s o n o f t h e t h r e e m a p s . T h e
b a s i c c h a n g e s o f m o r p h o l o g y d u e t o th e l a n d sl id e a n d i ts c o m p a r i s o n a r e s h o w n
o n t h e t h r e e p h o t o g r a m m e t r i c c o n t r o l m a p s , F i g . 4 - 6 .
A s s o o n a s t h e p l o t t in g o f t h e f ir s t m o d e l w a s f in i s h e d , a t r a n s p a r e n t r e t i c u le
o f g r i d li n e s w a s c o n s t r u c t e d o n t h e p l o t t i n g t a b l e w i t h i ts l i n e s p a r a l l e l t o t h e
X - a n d Y - a x e s o f t h e m a c h i n e . T h e s h a p e o f th e g r id w a s d e l i n e a te d b y t h e
Fig.3. Stereoscopic m ode l, 5x/J yea rs later 1963).
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l l 0 P. R, SALGUEIRO
l O m
L j
Fig.4. Lar ge-scale map of the 1956 model.
landslide Fig.5), 1958 photographs, and it was decided to use grid lines with 10 m
intervals. With this grid the locations of 680 points were obtained, for which the
coordinates X, Y and Z were read and registered simultaneously by means of the
EK3 print and the I.B.M. punch-card. The punch-card data were taken to the
electrical I.B.M.602 computing machine. The practical method of running readings
on the Wild A7 autographs to intervals of 10 m in the three models was very
simple, since a draftsman helped to carry the spot points by means of the X- and
Y-wheels of the plotting table. The operator merely moved the Wild A7 height disc
twice, to put the floatingmarkonthegroundinordertoobtainheightdoublereadings.
Photogrammetria
20 1965) 107-114
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LANDSLIDE INVESTIGA TIONBY MEA NS OF PHOTOGRAMMETRY 111
Fig.5. M ap of the 1958 model .
W i t h t h e p u n c h - c a r d s i t w a s p o s s i b le t o c a r r y o u t c o m p u t a t i o n s o f t h e a r e a
a n d t h e v o l u m e s o f t h e a f f e c te d re g i o n. T h e v o l u m e V , w a s c o m p u t e d a n d r e f e r re d
t o X , Y a n d Z a r b i t r a r y p l a n e s u s in g th e d a t a o f t h e p h o t o m o d e l o f 1 9 5 6 . V o l u m e s
V ~ a n d V 3 w e r e c o m p u t e d w i th t h e p h o t o m o d e l s ta k e n i n 1 9 5 8 a n d 1 9 6 3 . T h e
d i f f e r e n c e V 1 - V 2 = x V 1, g a v e u s a v o l u m e f o r t h e e n t i r e s o il m o v e m e n t d u e
t o t h e l a n d s l id e o v e r a n o l d t e r r a c e . 1 / 2 - V 3 = ~x V 2 , y i e l d s t h e e f f e c t w h i c h h a s
p r o d u c e d a d if f e r e n t i a l v o l u m e , d u e t o th e s e d i m e n t a t i o n , s i n k i n g o f s oi l, e r o s i o n
a n d w e a t h e r i n g e f fe c t s w h i c h h a v e t a k e n p l a c e i n t h e a r e a w i t h in a n i n t e rv a l o f
51 /2 yea r s .
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11 2 P.R . SALGUEIRO
Fig.6. M ap of the 1963 model.
T h e m e t h o d u s e d f o r t h e c o m p u t a t i o n o f t h e v o l u m e w a s b a s e d o n t h e
S i m p s o n s f o r m u l a s :
A
V = ~ ~Vhl + 2 ~ h 2 + 3~Vh.~ + 4~Yh4)
A
V = ~ h l + h 2 + h a )
Photogrammetria
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L A N D S L ID E I N V E ST I G A T IO N B Y M E A N S O F P H O T O G R A M M E T R Y 1 1 3
The area was computed using the simple orthogonal coordinates of the
points on the periphery:
2 A = ~ xi (Yi-a -Y~+1)
giving an area of 54,316 mL
The computed results gave the following figures concerning the mass of
soil moved over an older terrace. Seven days after the landslide took place the
movement was 48,895.5 mZ; 51/2 years after the second measurement, made in
1958, the sedimentation, erosion and sinking was 73,904.1 m L The total move-
F i g .7 . F r a c t u r e s o n w a l l s d e l in e a t e c o n c e n t r i c a r e a s a l o n g t h e l a n d s l id e a x e s .
Photogrammetria
2 0 1 9 6 5) 1 0 7 - 1 1 4
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11 4 P. R. SALGUEIRO
m ent s ince i ts o r ig ina l s t a t e , befo re t he l ands l ide t o ok p l ace , i s 122 ,7 99 .6 m 3. I t
h a s b e en p l an n e d t o co n t r o l t h is e f f ec t w i t h in an o t h e r 5 - y ea r p e r i o d .
A carefu l i nves t iga t ion o f f r ac tu res i n t he bu i ld ings shown on the aer i a l
pho tos wi th in the ne ighbor ing a rea c lose t o t he lands l ide , pa r t l y by g round inspec-
t i on and par t l y on the pho to grap h F ig .7 ) , shows c l ear ly t he p r inc ipa l ax i s o f t he
phenomenon ind ica t ing tha t a fu tu re l ands l ide wi l l o r ig ina t e a long tha t ax i s , and
the so i l ma ss which i s go ing to mov e will fo rm ano th er t e r race as i n t he case o f
areas o f s imi la r m orp ho lo gy nar row va l l eys ) . Th e conc en t r i c a rcs on the aer ia l
pho tos show the fu tu re m oving area t ha t wi ll cause des t ruc t ive e f fec t s. I t shou ld
b e co n c l u d ed t h a t ad eq u a t e s ecu r i t y me as u r e s m u s t b e co n s i d e r ed b e f o r e t h e o c -
cu r rence o f ano ther l ands l ide .
CONCLUSIONS
1 ) P h o t o g r am m et r y i s t h e ad eq u a t e , p r ec i s e an d ti me- m o n ey s av in g s o lu t io n
f o r co n t ro l o f l an d s li d e p h en o m en o n , p r o v i d ed t h a t ad eq u a t e a ir p h o t o g r ap h y i s
avai lable.
2 ) The a i r pho tograph ic i n t e rp re t a t i on , i n connec t ion wi th t he f ac t s found
ou t in the m orpho log ica l change s o f t he a rea s tud ied , g ives a c lear p i c tu re o f
occu r rence o f fu tu re even t s wh ich w ill t ake p l ace caus ing the des t ruc t ion o f a
l a rge nu m ber o f houses a s it i s show n in F ig .7 . A s a r esu l t o f t h is i n ference , t he
m os t appro pr i a t e ru l es m igh t be d raf t ed by the loca l techn ica l au thor i t i es i n o rder
to p reven t fu tu re l ands l ides .
3 ) Th e o r ig in o f t he l ands l ide can b e exp la ined , base d on the f ind ings by
mea n s o f p h o t o g r am m et r y an d g eo l o g i ca l o b s e r v a t io n s .
4 ) A carefu l phys i ca l ana lys i s based on the e f fec t s o f defo rmat ion , f r ac-
tu res , s i nk ing and d i sp l acement , wi l l permi t es t ab l i shmen t o f t he fo rce-vec to r d i s -
t r i bu t ion and i ts e f fec t s wi th in t he a rea .
Photogrammetria 20 1965) 107-114
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