,illu/ration3 ,! eruption ( ,c]ro ,negro
 ,volcano1 ne> ,leon1  ,nic>agua1 dur+  
,novemb] #aifh4                 ,u4 ,s4 
,dep>tm5t ( ! ,int]ior _/ ,u4 ,s4       
,geological ,survey                     
,volcanoes                              
by ,rob]t ,i4 ,till+    ,illu/ration3   
,cov] & ,title ,page3 ,lava f\nta9s &   
fl[s1 ,mauna  ,loa1 ,hawaii1 ,july #f1  
#aige4    ,volcanoes de/roy & volcanoes 
create4 ,! cata/rophic eruption (  ,m\nt
 ,/4 ,hel5s on ,may #ah1 #aihj1 made    
cle> ! awesome de/ructive  p[] ( a      
volcano4 ,yet1 ov] a "t span long] ?an  
human memory &  record1 volcanoes h     
play$ a key role 9 =m+ & modify+ !      
planet ^u :i* we live4 ,m ?an #hj p]c5t 
( ! ,e>?'s  surface--above & bel[ sea   
level--is ( volcanic orig94 ,gase\s     
emissions f volcanic v5ts ov] hundr$s ( 
millions ( ye>s =m$  ! ,e>?'s e>lie/    
oceans & atmosph]e1 :i* suppli$ !       
+r$i5ts vital to evolve & su/a9 life4   
,ov] geologic eons1  c\ntless volcanic  
eruptions h produc$ m\nta9s1 plateaus1 &

  pla9s1 :i* subsequ5t erosion & wea!r+ 
h sculpt$ into  maje/ic l&scapes & =m$  
f]tile soils4    ,ironically1 ^!        
volcanic soils & invit+ t]ranes h       
attract$1  & cont9ue to attract1 p to   
live on ! flanks ( volcanoes4  ,?us1 z  
population d5sity increases 9 regions ( 
active or  pot5tially active volcanoes1 
mank9d mu/ become increas+ly aw>e (  !  
haz>ds & le>n n to 8cr[d0 ! volcanoes4  
,p liv+ 9 !  %ad[ ( volcanoes mu/ live 9
 h>mony ) !m & expect1 &  %\ld plan =1  
p]iodic viol5t unlea%+s ( _! p5t-up     
en]gy4    ,?is booklet pres5ts a        
g5]aliz$ summ>y ( ! nature1 work+s1     
products1 & haz>ds ( ! common types (   
volcanoes ar\nd ! _w1  along ) a brief  
introduction to ! te*niques ( volcano   
monitor+  & rese>*4    ,illu/ration3    
,on ,augu/ #bd1 ,a4,d4 #gi1 ,vesuvius   
,volcano sudd5ly explod$ & de/roy$  !   
,roman cities ( ,pompeii & ,h]culaneum4 
,al?\gh ,vesuvius _h %[n  /irr+s ( life 
:5 a succession ( e>?quakes 9 ,a4,d4 #fc
 caus$  "s damage1 x _h be5 lit]ally    

quiet = hundr$s ( ye>s & 0  consid]$    
8ext9ct40 ,its surface & crat] 7 gre5 & 
cov]$ )  vegetation1 s ! eruption 0     
totally unexpect$4 ,yet 9 a few h\rs1   
hot volcanic a% & du/ buri$ ! two cities
 s ?or\ghly t _!  ru9s 7 n uncov]$ =    
ne>ly #a1gjj ye>s1 :5 ! discov]y (  an  
out] wall 9 #agdh />t$ a p]iod ( mod]n  
ar*eology4 ,vesuvius  has cont9u$ its   
activity int]mitt5tly ev] s9ce ,a4,d4   
#gi )  num]\s m9or eruptions & sev]al   
major eruptions occurr+ 9 #afca1  #agid1
 #ahgb1 #aijf & 9 #aidd 9 ! mid/ ( !    
,italian campaign (  ,_w ,w> ,,ii4      
,illu/ration3     ,9 ! ,unit$ ,/ates on 
,m>* #bg1 #aihj1 ,m\nt ,/4 ,hel5s       
,volcano 9 !  ,cascade ,range1 s\?we/]n 
,wa%+ton1 reawak5$ aft] m ?an a  c5tury 
( dormancy & provid$ a dramatic & tragic
 rem9d] t  !re are active volcanoes 9 ! 
8l[] #dh0 ,/ates z well z 9 ,hawaii  &  
,alaska4 ,! cata/rophic eruption ( ,m\nt
 ,/4 ,hel5s on ,may #ah1  #aihj1 &      
relat$ mudfl[s & flood+ caus$           
significant loss ( life  7#eg dead or   

miss+7 & prop]ty damage 7ov] #a4b       
billion74 ,m\nt ,/4  ,hel5s is expect$  
to rema9 int]mitt5tly active = mon?s or 
ye>s1  possibly ev5 decades4    ,! ^w   
8volcano0 comes f ! little isl& (       
,vulcano 9 !  ,m$it]ranean ,sea (f      
,sicily4 ,c5turies ago1 ! p liv+ 9 ?is  
area believ$ t ,vulcano 0 ! *imney ( !  
=ge ( ,vulcan--!  blacksmi? ( ! ,roman  
gods4 ,!y ?\ght t ! hot lava fragm5ts  &
 cl\ds ( du/ erupt+ f ,vulcano came f   
,vulcan's =ge z he  beat out ?und]bolts 
= ,jupit]1 k+ ( ! gods1 & weapons =     
,m>s1 ! god ( w>4 ,9 ,polynesia ! p     
attribut$ eruptive  activity to !       
beautiful b wra?ful ,pele1 ,goddess (   
,volcanoes1  :5ev] %e 0 angry or        
spiteful4 ,today we "k t volcanic       
eruptions are n sup]natural b c be /udi$
 & int]pret$ by  sci5ti/s4              
,! ,nature ( ,volcanoes      ,volcanoes 
are m\nta9s1 b !y are v diff]5t f o!r   
m\nta9s2 !y are n =m$ by fold+ & crumpl+
 or by uplift &  erosion4 ,in/ead1      
volcanoes are built by ! accumulation ( 

_! own  eruptive products--lava1 bombs  
7cru/$ ov] lava blobs71 a%fl[s1 &       
tephra 7airborne a% & du/74 ,a volcano  
is mo/ commonly a conical  hill or      
m\nta9 built ar\nd a v5t t connects )   
res]voirs (  molt5 rock bel[ ! surface (
 ! ,e>?4 ,! t]m volcano also ref]s  to !
 op5+ or v5t ?r\gh :i* ! molt5 rock &   
associat$  gases are expell$4           
,illu/ration3 ,f\nta9+ lava & volcanic  
debris dur+ ! #aiei  ,kilauea ,iki      
eruption ( ,kilauea ,volcano1 ,hawaii4  
,driv5 by buoyancy & gas pressure !     
molt5 rock1 :i* is light]  ?an !        
surr\nd+ solid rock1 =ces its way upw>d 
& may  ultimately break ?r\gh zones (   
weaknesses 9 ! ,e>?'s cru/4 ,if  s1 an  
eruption beg9s1 & ! molt5 rock may p\r f
 ! v5t z  non-explosive lava fl[s1 or x 
may %oot viol5tly into ! air z  d5se    
cl\ds ( lava fragm5ts4 ,l>g] fragm5ts   
fall back ar\nd !  v5t1 & accumulations 
( fall-back fragm5ts may move d[nslope z
 a%  fl[s "u ! =ce ( gravity4 ,"s ( !   
f9] eject$ mat]ials  may be c>ri$ by !  

w9d only to fall to ! gr\nd _m miles    
away4  ,! f9e/ a% p>ticles may be       
inject$ miles into ! atmosph]e &  c>ri$ 
_m times ar\nd ! _w by /ratosph]ic w9ds 
be=e  settl+ out4    ,molt5 rock bel[ ! 
surface ( ! ,e>? t rises 9 volcanic v5ts
  is kn[n z magma1 b aft] x erupts f a  
volcano x is call$  lava4 ,orig9at+ _m  
t5s ( miles b5ea? ! gr\nd1 ! asc5d+     
magma commonly conta9s "s cry/als1      
fragm5ts ( surr\nd+  7unmelt$7 rocks1 & 
dissolv$ gases1 b x is prim>ily a liquid
  compos$ pr9cipally ( oxyg51 silicon1  
alum9um1 iron1 magnesium1  calcium1     
sodium1 potassium1 titanium1 &          
manganese4 ,magmas also conta9  _m o!r  
*emical elem5ts 9 trace quantities4 ,^u 
cool+1 !  liquid magma may precipitate  
cry/als ( v>i\s m9]als until            
solidification is complete to =m an     
igne\s or magmatic rock4                
,illu/ration3 ,an idealiz$ diagram ( a  
volcano 9 an oceanic  environm5t 7left7 
& 9 a cont95tal environm5t 7"r74    ,!  
diagram bel[ %[s t heat conc5trat$ 9 !  

,e>?'s upp]  mantle raises temp]atures  
suffici5tly to melt ! rock locally by   
fus+ ! mat]ials ) ! l[e/ melt+          
temp]atures1 result+ 9  small1 isolat$  
blobs ( magma4 ,^! blobs !n collect1    
rise ?r\gh  conduits & fractures1 & "s  
ultimately may re-collect 9 l>g]        
pockets or res]voirs 78hold+ tanks07 a  
few miles b5ea? ! ,e>?'s  surface4      
,m\nt+ pressure )9 ! res]voir may drive 
! magma  fur!r upw>d ?r\gh /ructurally  
weak zones to erupt z lava at !         
surface4 ,9 a cont95tal environm5t1     
magmas are g5]at$ 9 !  ,e>?'s cru/ z    
well z at v>y+ dep?s 9 ! upp] mantle4 ,!
  v>iety ( molt5 rocks 9 ! cru/1 plus ! 
possibility ( mix+  ) molt5 mat]ials f !
 und]ly+ mantle1 leads to !  production 
( magmas ) widely diff]5t *emical       
compositions4    ,if magmas cool        
rapidly1 z might be expect$ ne> or on ! 
,e>?'s  surface1 !y solidify to =m      
igne\s rocks t are f9ely cry/all9e  or  
glassy ) few cry/als4 ,accord+ly1 lavas1
 :i* ( c\rse are  v rapidly cool$1 =m   

volcanic rocks typically *>act]iz$ by a 
small p]c5tage ( cry/als or fragm5ts set
 9 a matrix ( glass  7qu5*$ or          
sup]-cool$ magma7 or f9] gra9$ cry/all9e
 mat]ials4  ,if magmas nev] brea* !     
surface to erupt & rema9 deep und]gr\nd1
  !y cool mu* m sl[ly & ?us all[ ample  
"t to su/a9 cry/al  precipitation &     
gr[?1 result+ 9 ! =mation ( co>s] gra9$1
  ne>ly completely cry/all9e1 igne\s    
rocks4 ,subsequ5t to f9al               
cry/allization & solidification1 su*    
rocks c be exhum$ by erosion  _m ?\s&s  
or millions ( ye>s lat] & be expos$ z   
l>ge bodies  ( s-call$ granitic rocks1  
z1 = example1 ^? spectacul>ly  display$ 
9 ,yosemite ,national ,p>k & o!r p>ts ( 
! maje/ic  ,si]ra ,nevada m\nta9s (     
,cali=nia4    ,lava is r$ hot :5 x p\rs 
or bla/s out ( a v5t b soon *anges  to  
d>k r$1 gray1 black1 or "s o!r color z x
 cools &  solidifies4 ,v hot1 gas-ri*   
lava conta9+ abundant iron &  magnesium 
is fluid & fl[s l hot t>1 :]eas cool]1  
gas-poor lava  high 9 silicon1 sodium1 &

 potassium fl[s sluggi%ly1 l ?ick  honey
 9 "s cases or 9 o!rs l pa/y1 blocky    
masses4    ,illu/ration3 ,two           
,polynesian t]ms are us$ to id5tify !   
surface  "* ( ,hawaiian lava fl[s4 ,aa1 
a basalt ) a r\gh1 blocky  appe>ance1   
mu* l furnace slag1 is %[n at ! top4    
,pahoehoe1 a  m fluid v>iety ) a smoo?1 
sat9y & sometimes glassy  appe>ance1 is 
%[n at ! bottom4    ,all magmas conta9  
dissolv$ gases1 & z !y rise to ! surface
 to  erupt1 ! conf9+ pressures are r$uc$
 & ! dissolv$ gases are  lib]at$ ei!r   
quietly or explosively4 ,if ! lava is a 
?9 fluid  7n visc\s71 ! gases may escape
 easily4 ,b if ! lava is ?ick &  pa/y   
7highly visc\s71 ! gases w n move freely
 b w build up  trem5d\s pressure1 &     
ultimately escape ) explosive viol5ce4  
,gases 9 lava may be comp>$ ) ! gas 9 a 
bottle ( a c>bonat$  s(t dr9k4 ,if y put
 y\r ?umb ov] ! top ( ! bottle & %ake  x
 vigor\sly1 ! gas sep>ates f ! dr9k &   
=ms bubbles4 ,:5  y remove y\r ?umb     
abruptly1 !re is a m9iature explosion ( 

gas  & liquid4 ,! gases 9 lava behave 9 
some:at ! same way4 ,_!  sudd5 expansion
 causes ! t]rible explosions t ?r[ out  
great  masses ( solid rock z well z     
lava1 du/1 & a%es4    ,! viol5t         
sep>ation ( gas f lava may produce rock 
fro? call$  pumice4 ,"s ( ?is fro? is s 
light--because ( ! _m gas  bubbles--t x 
floats on wat]4 ,9 _m eruptions1 ! fro? 
is  %att]$ explosively into small       
fragm5ts t are hurl$ high into !  air 9 
! =m ( volcanic c9d]s 7r$ or black71    
volcanic a%  7commonly tan or gray71 &  
volcanic du/4    ,illu/ration3 ,dur+ !  
#aiei eruption ( ,kilauea ,iki1 f\nta9+ 
lava  & volcanic debris completely      
block$ sev]al ( ! roads 9 !  ,hawaii    
,volcanoes ,national ,p>k4              
,pr9cipal ,types ( ,volcanoes           
,geologi/s g5]ally gr\p volcanoes into  
f\r ma9 k9ds--c9d] cones1  composite    
volcanoes1 %ield volcanoes1 & lava      
domes4                                  
,c9d] cones    ,c9d] cones are ! simple/
 type ( volcano4 ,!y are built f        

p>ticles & blobs ( congeal$ lava eject$ 
f a s+le v5t4 ,z !  gas-*>g$ lava is    
bl[n viol5tly into ! air1 x breaks into 
small  fragm5ts t solidify & fall z     
c9d]s ar\nd ! v5t to =m a  circul> or   
oval cone4 ,mo/ c9d] cones h a b[l-%ap$ 
crat] at  ! summit & r>ely rise m ?an a 
?\s& feet or s above _!  surr\nd+s4     
,c9d] cones are num]\s 9 we/]n ,nor?    
,am]ica z well  z ?r\gh\t o!r volcanic  
t]ra9s ( ! _w4    ,illu/ration3         
,s*ematic repres5tation ( ! int]nal     
/ructure ( a  typical c9d] cone4    ,9  
#aidc a c9d] cone />t$ gr[+ on a f>m ne>
 ! village (  ,p>cut9 9 ,mexico4        
,explosive eruptions caus$ by gas       
rapidly exp&+  & escap+ f molt5 lava =m$
 c9d]s t fell back ar\nd !  v5t1 build+ 
up ! cone to a height ( #a1bjj feet4 ,! 
la/ explosive  eruption left a          
funnel-%ap$ crat] at ! top ( ! cone4    
,aft] !  excess gases _h l>gely         
dissipat$1 ! molt5 rock quietly p\r$ out
  on ! surr\nd+ surface ( ! cone & mov$ 
d[nslope z lava  fl[s4 ,?is ord] (      

ev5ts--eruption1 =mation ( cone & crat]1
 lava  fl[--is a common sequ5ce 9 !     
=mation ( c9d] cones4    ,illu/ration3  
,p>cut9 ,volcano1 ,mexico1 is a c9d]    
cone ris+  approximately #a1bjj feet    
above ! surr\nd+ pla94    ,dur+ #i ye>s 
( activity1 ,p>cut9 built a prom95t     
cone1 cov]$  ab\t #ajj squ>e miles )    
a%es1 & de/roy$ ! t[n ( ,san ,juan4     
,geologi/s f _m p>ts ( ! _w /udi$       
,p>cut9 dur+ its  lifetime & le>n$ a    
great deal ab\t volcanism1 its products1
 & !  modification ( a volcanic l&=m by 
erosion4                                
,composite volcanoes    ,"s ( ! ,e>?'s  
gr&e/ m\nta9s are composite             
volcanoes--sometimes call$              
/ratovolcanoes4 ,!y are typically       
/eep-sid$1 symmetrical cones ( l>ge     
dim5sion built ( alt]nat+  lay]s ( lava 
fl[s1 volcanic a%1 c9d]s1 blocks1 &     
bombs & may  rise z mu* z #h1jjj feet   
above _! bases4 ,"s ( ! mo/  conspicu\s 
& beautiful m\nta9s 9 ! _w are composite
  volcanoes1 includ+ ,m\nt ,fuji 9      

,japan1 ,m\nt ,cotopaxi 9 ,ecuador1     
,m\nt ,%a/a 9 ,cali=nia1 ,m\nt ,hood 9  
,oregon1 & ,m\nt ,/4 ,hel5s  & ,m\nt    
,ra9i] 9 ,wa%+ton4    ,mo/ composite    
volcanoes h a crat] at ! summit :i*     
conta9s a  c5tral v5t or a clu/]$ gr\p (
 v5ts4 ,lavas ei!r fl[ ?r\gh  breaks 9 !
 crat] wall or issue f fissures on !    
flanks ( !  cone4 ,lava1 solidifi$ )9 ! 
fissures1 =ms dikes t act z ribs  :i*   
greatly /r5g!n ! cone4    ,illu/ration3 
,s*ematic repres5tation ( ! int]nal     
/ructure ( a  typical composite volcano4
    ,! ess5tial feature ( a composite   
volcano is a conduit sy/em ?r\gh  :i*   
magma f a res]voir deep 9 ! ,e>?'s cru/ 
rises to !  surface4 ,! volcano is built
 up by ! accumulation ( mat]ial erupt$  
?r\gh ! conduit & increases 9 size z    
lava1 c9d]s1 a%1 etc41  are add$ to its 
slopes4    ,:5 a composite volcano      
becomes dormant1 erosion beg9s to de/roy
 !  cone4 ,z ! cone is /ripp$ away1 !   
h>d5$ magma fill+ !  conduit 7! volcanic
 plug7 & fissures 7! dikes7 becomes     

expos$1  & x too is sl[ly r$uc$ by      
erosion4 ,f9ally1 all t rema9s is  !    
plug & dike complex project+ above ! l& 
surface--a telltale  remnant ( ! vani%$ 
volcano4    ,illu/ration3 ,%i%ald9      
,volcano1 an impos+ composite cone1 t[]s
  #i1cgb feet above sea level 9 !       
,aleutian ,isl&s1 ,alaska4    ,an       
int]e/+ v>iation ( a composite volcano c
 be se5 at ,crat]  ,lake 9 ,oregon4 ,f  
:at geologi/s c int]pret ( its pa/1 a   
high  volcano--call$ ,m\nt              
,mazama--probably simil> 9 appe>ance to 
pres5t-day ,m\nt ,ra9i] 0 once locat$ at
 ?is spot4 ,foll[+ a  s]ies ( trem5d\s  
explosions ab\t #f1hjj ye>s ago1 !      
volcano lo/  its top4 ,enorm\s volumes (
 volcanic a% & du/ 7 expell$ &  swept   
d[n ! slopes z a% fl[s & avalan*es4 ,^! 
l>ge-volume  explosions rapidly dra9$ ! 
lava b5ea? ! m\nta9 & weak5$  ! upp] "p4
 ,! top !n collaps$ to =m a l>ge        
depression1 :i*  lat] fill$ ) wat] & is 
n[ completely occupi$ by beautiful      
,crat] ,lake4 ,a la/ gasp ( eruptions   

produc$ a small c9d] cone1  :i* rises   
above ! wat] surface z ,wiz>d ,isl& ne> 
! rim ( !  lake4 ,depressions su* z     
,crat] ,lake1 =m$ by collapse (         
volcanoes1  are kn[n z cald]as4 ,!y are 
usually l>ge1 /eep-wall$1  bas9-%ap$    
depressions =m$ by ! collapse ( a l>ge  
area ov]1  & ar\nd1 a volcanic v5t or   
v5ts4 ,cald]as range 9 =m & size  f     
r\ghly circul> depressions #a to #ae    
miles 9 diamet] to huge  elongat$       
depressions z mu* z #fj miles long4     
,illu/ration3 ,crat] ,lake1 ,oregon2    
,wiz>d ,isl&1 a c9d] cone1 rises  above 
! lake surface4                       ,!
 ,evolution ( a ,composite ,volcano3    
,illu/ration3 a4 ,magma1 ris+ upw>d     
?r\gh a conduit1 erupts at !  ,e>?'s    
surface to =m a volcanic cone4 ,lava    
fl[s spread ov] !  surr\nd+ area4       
,illu/ration3 b4 ,z volcanic activity   
cont9ues1 p]haps ov] spans (  hundr$s ( 
ye>s1 ! cone is built to a great height 
& lava fl[s  =m an ext5sive plateau     
ar\nd its base4 ,dur+ ?is p]iod1 /reams 

enl>ge & deep5 _! valleys4              
,illu/ration3 c4 ,:5 volcanic activity  
ceases1 erosion />ts to  de/roy ! cone4 
,aft] ?\s&s ( ye>s1 ! great cone is     
/ripp$  away to expose ! h>d5$ 8volcanic
 plug0 9 ! conduit4 ,dur+ ?is  p]iod (  
inactivity1 /reams broad5 _! valleys &  
dissect ! lava  plateau to =m isolat$   
lava-capp$ mesas4    ,illu/ration3 d4   
,cont9u$ erosion removes all traces ( ! 
cone &  ! l& is worn d[n to a surface ( 
l[ relief4 ,all t rema9s is a  project+ 
plug or 8volcanic neck10 a small        
lava-capp$ mesa1 &  ve/iges ( ! once    
l(ty volcano & its surr\nd+ lava        
plateau4                                
,%ield volcanoes    ,%ield volcanoes1 ! 
?ird type ( volcano1 are built almo/    
entirely  ( fluid lava fl[s4 ,fl[ aft]  
fl[ p\rs out 9 all directions f a       
c5tral summit v5t1 or gr\p ( v5ts1      
build+ a broad1 g5tly  slop+ cone (     
flat1 domical %ape1 ) a pr(ile mu* l t (
 a  w>rior's %ield4 ,!y are built up    
sl[ly by ! accretion ( ?\s&s  ( highly  

fluid lava fl[s call$ basalt lava t     
spread widely ov]  great di/ances1 & !n 
cool z ?91 g5tly dipp+ %eets4 ,lavas    
also commonly erupt f v5ts along        
fractures 7rift zones7 t develop  on !  
flanks ( ! cone4 ,"s ( ! l>ge/ volcanoes
 9 ! _w  are %ield volcanoes4 ,9 nor!rn 
,cali=nia & ,oregon1 _m %ield  volcanoes
 h diamet]s ( #c or #d miles & heights (
 #a1ejj to #b1jjj  feet4 ,! ,hawaiian   
,isl&s are compos$ ( l9e> *a9s ( ^!     
volcanoes includ+ ,kilauea & ,mauna ,loa
 on ! isl& ( ,hawaii--two (  ! _w's mo/ 
active volcanoes4 ,! floor ( ! ocean is 
m ?an  #ae1jjj feet deep at ! bases ( ! 
isl&s4 ,z ,mauna ,loa1 ! l>ge/  ( !     
%ield volcanoes 7& also ! _w's l>ge/    
active volcano71  projects #ac1fgg feet 
above sea level1 its top is ov] #bh1jjj 
feet above  ! deep ocean floor4    ,9 "s
 eruptions1 basaltic lava p\rs out      
quietly f long fissures  in/ead ( c5tral
 v5ts & floods ! surr\nd+ c\ntryside )  
lava fl[ ^u lava fl[1 =m+ broad         
plateaus4 ,lava plateaus ( ?is  type c  

be se5 9 ,icel&1 s\!a/]n ,wa%+ton1 ea/]n
 ,oregon1  & s\!rn ,idaho4 ,along !     
,snake ,riv] 9 ,idaho1 & ! ,columbia    
,riv] 9 ,wa%+ton & ,oregon1 ^! lava fl[s
 are beautifully expos$  & measure m ?an
 a mile 9 total ?ickness4               
,illu/ration3 ,mauna ,loa ,volcano1     
,hawaii1 a giant among ! active         
volcanoes ( ! _w2 sn[-capp$ ,mauna ,kea 
,volcano 9 ! di/ance4    ,illu/ration3  
,! int]nal /ructure ( a typical %ield   
volcano4                                
,lava domes    ,illu/ration3 ,a sket* ( 
! havoc wr\ght 9 ,/4 ,pi]re ,h>bor on   
,m>t9ique dur+ ! eruption ( ,mont ,pele 
9 #aijb4    ,volcanic or lava domes are 
=m$ by relatively small1 bulb\s masses (
  lava too visc\s to fl[ any great      
di/ance2 consequ5tly1 on extrusion1  !  
lava piles ov] & ar\nd its v5t4 ,a dome 
gr[s l>gely by  expansion f )94 ,z x    
gr[s its out] surface cools & h>d5s1  !n
 %att]s1 spill+ loose fragm5ts d[n its  
sides4 ,"s domes =m  craggy knobs or    
sp9es ov] ! volcanic v5t1 :]eas o!rs =m 

%ort1 /eep-sid$ lava fl[s kn[n z        
8c\lees40 ,volcanic domes  commonly     
occur )9 ! crat]s or on ! flanks ( l>ge 
composite  volcanoes4 ,! ne>ly circul>  
,nov>upta ,dome t =m$ dur+ !  #aiab     
eruption ( ,katmai ,volcano1 ,alaska1   
measures #hjj feet across &  #bjj feet  
high4 ,! int]nal /ructure ( ?is         
dome--def9$ by lay]+  ( lava fann+ upw>d
 & outw>d f ! c5t]--indicates t x  grew 
l>gely by expansion f )94 ,mont ,pele 9 
,m>t9ique1 ,less]  ,antilles1 & ,lass5  
,peak & ,mono domes 9 ,cali=nia are     
examples (  lava domes4 ,an extremely   
de/ructive eruption accompani$ ! gr[? ( 
a dome at ,mont ,pele 9 #aijb4 ,! coa/al
 t[n ( ,/4 ,pi]re1 ab\t #d  miles       
d[nslope to ! s\?1 0 demoli%$ & ne>ly   
#cj1jjj  inhabitants 7 kill$ by an      
inc&esc5t1 high-velocity a% fl[ &       
associat$ hot gases & volcanic du/4     
,only two m5 surviv$2 "o  because he 0 9
 a poorly v5tilat$1 dungeon-l jail cell 
& !  o!r :o someh[ made 8 way safely    
?r\gh ! burn+ city4    ,illu/ration3 ,! 

,nov>upta ,dome =m$ dur+ ! #aiab        
eruption (  ,katmai ,volcano1 ,alaska4  
,illu/ration3 ,s*ematic repres5tation ( 
! int]nal /ructure ( a  typical volcanic
 dome4                                  
,o!r ,volcanic ,/ructures               
,plugs 7necks7    ,congeal$ magma1 along
 ) fragm5tal volcanic & wallrock        
mat]ials1  c be pres]v$ 9 ! fe$+        
conduits ( a volcano ^u cessation (     
activity4 ,^! pres]v$ rocks =m crudely  
cyl9drical masses1 f  :i* project       
radiat+ dikes2 !y may be visualiz$ z !  
fossil  rema9s ( ! inn>ds ( a volcano 7!
 s-call$ 8volcanic plumb+  sy/em07 & are
 ref]r$ to z volcanic plugs or necks4 ,!
 igne\s  mat]ial 9 a plug may h a range 
( composition simil> to t (  associat$  
lavas or a%1 b may also include fragm5ts
 & blocks (  d5s]1 co>s] gra9$          
rocks--high] 9 iron & magnesium1 l[] 9  
silicon--?\ght to be samples ( ! ,e>?'s 
deep cru/ or upp] mantle  pluck$ &      
transport$ by ! asc5d+ magma4 ,_m plugs 
& necks are  l>gely or :olly compos$ (  

fragm5tal volcanic mat]ial & (  fragm5ts
 ( wallrock1 :i* c be ( any type4 ,plugs
 t be> a  p>ticul>ly /rong impr9t (     
explosive eruption ( highly gas-*>g$    
magma are call$ diatremes or            
tuff-breccia4    ,volcanic plugs are    
believ$ to ov]lie a body ( magma :i*    
c\ld be  ei!r /ill l>gely liquid or     
completely solid dep5d+ on ! /ate  (    
activity ( ! volcano4 ,plugs are kn[n1  
or po/ulat$1 to be  commonly funnel %ap$
 & to tap] d[nw>d into bodies increas+ly
  elliptical 9 plan or elongat$ to      
dike-l =ms4 ,typically1 volcanic  plugs 
& necks t5d to be m resi/ant to erosion 
?an _!  enclos+ rock =mations4 ,?us1    
aft] ! volcano becomes inactive &       
deeply erod$1 ! exhum$ plug may /& up 9 
bold relief z an  irregul>1 column>     
/ructure4 ,"o ( ! be/ kn[n & mo/        
spectacul> diatremes 9 ! ,unit$ ,/ates  
is ,%ip ,rock 9 ,new ,mexico1  :i* t[]s 
"s #a1gjj feet above ! m deeply erod$   
surr\nd+  pla94 ,volcanic plugs1 includ+
 diatremes1 are f\nd else:]e 9 !  we/]n 

,unit$ ,/ates & also 9 ,g]many1 ,s\?    
,africa1 ,tanzania1 &  ,sib]ia4         
,illu/ration3 ,%ip ,rock1 ,san ,juan    
,c\nty1 ,new ,mexico4                   
,ma>s    ,also call$ 8tuff cones10 ma>s 
are %all[1 flat-floor$ crat]s t         
sci5ti/s int]pret h =m$ above diatremes 
z a result ( a  viol5t expansion (      
magmatic gas or /eam2 deep erosion ( a  
ma>  presumably w\ld expose a diatreme4 
,ma>s range 9 size f #bjj to  #f1ejj    
feet across & f #cj to #fej feet deep1 &
 mo/ are commonly  fill$ ) wat] to =m   
natural lakes4 ,mo/ ma>s h l[ rims      
compos$ ( a mixture ( loose fragm5ts (  
volcanic rock & rocks torn  f ! walls ( 
! diatreme4    ,ma>s occur 9 ! we/]n    
,unit$ ,/ates1 9 ! ,eifel region (      
,g]many1 & 9 o!r geologically "y        
volcanic regions ( ! _w4  ,an excell5t  
example ( a ma> is ,zuni ,salt ,lake 9  
,new ,mexico1 a  %all[ sal9e lake t     
occupies a flat-floor$ crat] ab\t #f1ejj
 feet  across & #djj feet deep4 ,its l[ 
rim is compos$ ( loose pieces (         

basaltic lava & wallrocks 7s&/one1 %ale1
 lime/one7 ( !  und]ly+ diatreme1 z well
 z r&om *unks ( anci5t cry/all9e  rocks 
bla/$ upw>d f great dep?s4              
,illu/ration3 ,zuni ,salt ,lake ,ma>1   
,catron ,c\nty1 ,new ,mexico4           
,nonvolcanic crat]s    ,"s well-expos$1 
ne>ly circul> areas ( int5sely de=m$    
s$im5t>y rocks1 9 :i* a c5tral v5t-l    
feature is surr\nd$ by  a r+-%ap$       
depression1 resemble volcanic /ructures 
9 gross =m4 ,z  no cle> evid5ce (       
volcanic orig9 c\ld be f\nd 9 or ne> ^! 
/ructures1 sci5ti/s initially describ$  
!m z 8cryptovolcanic10 a  t]m n[ r>ely  
us$4 ,rec5t /udies h %[n t n all crat]s 
are  ( volcanic orig94 ,impact crat]s1  
=m$ by collisions ) ! ,e>?  ( l>ge      
meteorites1 a/]oids1 or comets1 %>e )   
volcanoes !  impr9ts ( viol5t orig91 z  
evid5c$ by sev]e disruption1 & ev5      
local melt+1 ( rock4 ,fragm5ts (        
meteorites or *emically detectable      
traces ( extrat]re/rial mat]ials &      
indications ( /rong =ces  act+ f above1 

r ?an f bel[1 di/+ui% impact f  volcanic
 features4    ,o!r possible explanations
 = ^! nonvolcanic crat]s include        
subsurface salt-dome intrusion 7&       
subsequ5t dissolution &  collapse72     
collapse caus$ by subsurface lime/one   
dissolution &_/or  gr\nd-wat] )drawal2 &
 collapse relat$ to melt+ ( glacial ice4
  ,an impressive example ( an impact    
/ructure is ,meteor ,crat]1 ,ariz41  :i*
 is visit$ by ?\s&s ( t\ri/s ea* ye>4   
,?is impact crat]1  #d1jjj feet 9       
diamet] & #fjj feet deep1 0 =m$ 9 !     
geologic  pa/ 7probably #cj1jjj-ej1jjj  
ye>s be=e pres5t7 by a meteorite  /rik+ 
! ,e>? at a spe$ ( _m ?\s&s ( miles p]  
h\r4    ,9 addition to ,meteor ,crat]1 v
 fre%1 morphologically di/9ct1  impact  
crat]s are f\nd at ?ree sites ne>       
,odessa1 ,tex41 z well z #aj  or #ab o!r
 locations 9 ! _w4 ,( ! m deeply erod$1 
less  obvi\s1 po/ulat$ impact /ructures1
 !re are ab\t t5  well-e/abli%$ sites 9 
! ,unit$ ,/ates & p]haps #hj or #ij     
else:]e 9 ! _w4    ,illu/ration3 ,meteor

 ,crat]1 ,arizona4    ,illu/ration3     
,m\nt ,/4 ,hel5s1 ab\t noon1 ,may #ah1  
#aihj4                                  
,types ( ,volcanic ,eruptions      ,dur+
 an episode ( activity1 a volcano       
commonly displays a di/9ctive  patt]n ( 
behavior4 ,"s mild eruptions m]ely      
dis*>ge /eam &  o!r gases1 :]eas o!r    
eruptions quietly extrude quantities (  
lava4  ,! mo/ spectacul> eruptions      
consi/ ( viol5t explosions t bla/  great
 cl\ds ( gas-lad5 debris into !         
atmosph]e4    ,! type ( volcanic        
eruption is (t5 label$ ) ! "n ( a       
well-kn[n volcano :]e *>act]i/ic        
behavior is simil>--h5ce !  use ( su*   
t]ms z 8,/rombolian10 8,vulcanian10     
8,vesuvian10 8,pelan10  8,hawaiian10 &  
o!rs4 ,"s volcanoes may exhibit only "o 
*>act]i/ic type ( eruption dur+ an      
int]val ( activity--o!rs  may display an
 entire sequ5ce ( types4    ,9 a        
,/rombolian-type eruption obs]v$ dur+ ! 
#aife activity (  ,iraz ,volcano 9 ,co/a
 ,rica1 huge clots ( molt5 lava bur/ f !

  summit crat] to =m lum9\s arcs ?r\gh !
 sky4 ,collect+ on !  flanks ( ! cone1  
lava clots comb9$ to /ream d[n ! slopes 
9  fi]y rivulets4    ,illu/ration3 ,iraz
 ,volcano1 ,co/a ,rica1 #aife4    ,9    
contra/1 ! eruptive activity ( ,p>cut9  
,volcano 9 #aidg  demon/rat$ a          
8,vulcanian0-type eruption1 9 :i* a d5se
 cl\d (  a%-lad5 gas explodes f ! crat] 
& rises high above ! peak4  ,/eam+ a%   
=ms a :iti% cl\d ne> ! upp] level ( !   
cone4    ,9 a 8,vesuvian0 eruption1 z   
typifi$ by ! eruption ( ,m\nt ,vesuvius 
9 ,italy 9 ,a4,d4 #gi1 great quantities 
( a%-lad5 gas are viol5tly  dis*>g$ to  
=m a caulifl[]-%ap$ cl\d high above !   
volcano4    ,illu/ration3 ,p>cut9       
,volcano1 ,mexico1 #aidg4               
,illu/ration3 ,m\nt ,vesuvius ,volcano1 
,italy1 #aidd4    ,9 a 8,pelan0 or 8,nue
 ,ard5te0 7gl[+ cl\d7 eruption1 su* z   
occurr$ on ! ,mayon ,volcano 9 !        
,philipp9es 9 #aifh1 a l>ge  quantity ( 
gas1 du/1 a%1 & inc&esc5t lava fragm5ts 
are bl[n  out ( a c5tral crat]1 fall    

back1 & =m tongue-l1 gl[+  avalan*es t  
move d[nslope at velocities z great z   
#ajj miles p]  h\r4 ,su* eruptive       
activity c cause great de/ruction & loss
 (  life if x occurs 9 populat$ areas1 z
 demon/rat$ by ! deva/ation  ( ,/4      
,pi]re dur+ ! #aijb eruption ( ,mont    
,pele on ,m>t9ique1  ,less] ,antilles4  
8,hawaiian0 eruptions may occur along   
fissures or fractures t s]ve z  l9e>    
v5ts1 su* z dur+ ! eruption ( ,mauna    
,loa ,volcano 9 ,hawaii  9 #aiej2 or !y 
may occur at a c5tral v5t su* z dur+ !  
#aiei  eruption 9 ,kilauea ,iki ,crat] (
 ,kilauea ,volcano1 ,hawaii4 ,9         
fissure-type eruptions1 molt51 inc&esc5t
 lava spurts f a fissure  on ! volcano's
 rift zone & fe$s lava /reams t fl[     
d[nslope4  ,9 c5tral-v5t eruptions1 a   
f\nta9 ( fi]y lava spurts to a height  (
 sev]al hundr$ feet or m4 ,su* lava may 
collect 9 old pit  crat]s to =m lava    
lakes1 or =m cones1 or fe$ radiat+ fl[s4
    ,illu/ration3 ,mauna ,loa ,volcano1 
,hawaii1 #aiej4    8,phreatic0 7or      

/eam-bla/7 eruptions are driv5 by       
explosive exp&+  /eam result+ f cold    
gr\nd or surface wat] com+ into contact 
) hot rock or magma4 ,! di/+ui%+ feature
 ( phreatic  explosions is t !y only    
bla/ out fragm5ts ( preexi/+ solid  rock
 f ! volcanic conduit2 no new magma is  
erupt$4 ,phreatic  activity is g5]ally  
weak1 b c be q viol5t 9 "s cases1 su*  z
 ! #aife eruption ( ,taal ,volcano1     
,philipp9es1 & ! #aige-gf  activity at  
,la ,s\frire1 ,guadel\pe 7,less]        
,antilles74    ,! mo/ p[]ful eruptions  
are call$ 8pl9ian0 & involve !          
explosive ejection ( relatively visc\s  
lava4 ,l>ge pl9ian  eruptions--su* z    
dur+ #ah ,may #aihj at ,m\nt ,/4 ,hel5s 
or1 m  rec5tly1 dur+ #ae ,june #aiia at 
,p9atubo 9 ! ,philipp9es--c s5d  a% &   
volcanic gas t5s ( miles into ! air4 ,! 
result+ a%  fall\t c affect l>ge areas  
hundr$s ( miles d[nw9d4 ,fa/-mov+       
deadly pyrocla/ic fl[s 78nues ard5tes07 
are also commonly associat$  ) pl9ian   
eruptions4    ,illu/ration3 ,kilauea    

,volcano1 ,hawaii1 #aiei4               
,illu/ration3 ,taal ,volcano1           
,philipp9es1 #aife4                     
,subm>9e ,volcanoes      ,subm>9e       
volcanoes & volcanic v5ts are common    
features on c]ta9  zones ( ! ocean      
floor4 ,"s are active at ! pres5t "t &1 
9  %all[ wat]1 disclose _! pres5ce by   
bla/+ /eam & rock-debris  high above !  
surface ( ! sea4 ,_m o!rs lie at su*    
great dep?s  t ! trem5d\s weight ( !    
wat] above !m results 9 high1  conf9+   
pressure & prev5ts ! =mation & explosive
 release (  /eam & gases4 ,ev5 v l>ge1  
deep-wat] eruptions may n di/urb  !     
ocean surface4    ,illu/ration3         
,s*ematic repres5tation ( a typical     
subm>9e eruption  9 ! op5 ocean4    ,!  
unlimit$ supply ( wat] surr\nd+ subm>9e 
volcanoes c cause  !m to behave         
diff]5tly f volcanoes on l&4 ,viol5t1   
/eam-bla/  eruptions take place :5 sea  
wat] p\rs into active %all[ subm>9e     
v5ts4 ,lava1 erupt+ onto a %all[ sea    
floor or fl[+ into ! sea  f l&1 may cool

 s rapidly t x %att]s into s& & rubble4 
,! result is ! production ( huge am\nts 
( fragm5tal volcanic  debris4 ,! fam\s  
8black s&0 bea*es ( ,hawaii 7 creat$    
virtually  in/antane\sly by ! viol5t    
int]action betwe5 hot lava & sea  wat]4 
,on ! o!r h&1 rec5t obs]vations made f  
deep-div+  subm]sibles h %[n t "s       
subm>9e eruptions produce fl[s &  o!r   
volcanic /ructures rem>kably simil> to  
^? =m$ on l&4  ,rec5t /udies h reveal$ !
 pres5ce ( spectacul>1  high-temp]ature 
hydro!rmal plumes & v5ts 7call$         
8smok]s07 along  "s p>ts ( ! mid-oceanic
 volcanic rift sy/ems4 ,h[ev]1 to date1 
no direct obs]vation has be5 made ( a   
deep subm>9e eruption 9  progress4      
,dur+ an explosive subm>9e eruption 9 ! 
%all[ op5 ocean1  enorm\s piles ( debris
 are built up ar\nd ! active volcanic   
v5t4  ,ocean curr5ts rework ! debris 9  
%all[ wat]1 :ile o!r debris  slumps f ! 
upp] "p ( ! cone & fl[s into deep wat]  
along  ! sea floor4 ,f9e debris & a% 9 !
 eruptive plume are scatt]$  ov] a wide 

area 9 airborne cl\ds4 ,co>se debris 9 !
 same eruptive  plume ra9s into ! sea & 
settles on ! flanks ( ! cone4 ,pumice  f
 ! eruption floats on ! wat] & drifts ) 
! ocean curr5ts  ov] a l>ge area4       
,illu/ration3 ,subm>9e eruption (       
,myoj9-%o ,volcano1 ,izu ,isl&s1  ,japan
 on ,septemb] #bc1 #aieb4               
,geys]s1 ,fum>oles1 & ,hot ,spr+s       
,geys]s1 fum>oles 7also call$           
solfat>as71 & hot spr+s are  g5]ally    
f\nd 9 regions ( "y volcanic activity4  
,surface wat]  p]colates d[nw>d ?r\gh ! 
rocks bel[ ! ,e>?'s surface to          
high-temp]ature regions surr\nd+ a magma
 res]voir1 ei!r active or  rec5tly      
solidifi$ b /ill hot4 ,!re ! wat] is    
heat$1 becomes  less d5se1 & rises back 
to ! surface along fissures & cracks4   
,sometimes ^! features are call$ 8dy+   
volcanoes0 because !y seem  to repres5t 
! la/ /age ( volcanic activity z !      
magma1 at dep?1  cools & h>d5s4         
,erupt+ geys]s provide spectacul>       
displays ( und]gr\nd en]gy  sudd5ly     

unlea%$1 b _! me*anisms are n completely
 und]/ood4  ,l>ge am\nts ( hot wat] are 
presum$ to fill und]gr\nd cavities4  ,! 
wat]1 ^u fur!r heat+1 is viol5tly eject$
 :5 a portion (  x sudd5ly fla%es into  
/eam4 ,?is cycle c be repeat$ )         
rem>kable regul>ity1 z = example1 at    
,old ,fai?ful ,geys] 9  ,yell[/one      
,national ,p>k1 :i* erupts on an av]age 
( ab\t once  e #fe m9utes4              
,illu/ration3 ,old ,fai?ful ,geys]1     
,yell[/one ,national ,p>k1 ,wyom+4      
,fum>oles1 :i* emit mixtures ( /eam &   
o!r gases1 are f$ by  conduits t pass   
?r\gh ! wat] table be=e rea*+ ! surface 
( ! gr\nd4 ,hydrog5 sulfide 7,h,s71 "o (
 ! typical gases issu+  f fum>oles1     
readily oxidizes to sulfuric acid &     
native sulfur4  ,?is acc\nts = ! int5se 
*emical activity & brightly color$      
rocks 9 _m !rmal areas4    ,hot spr+s   
occur 9 _m !rmal areas :]e ! surface ( !
 ,e>?  int]sects ! wat] table4 ,!       
temp]ature & rate ( dis*>ge ( hot  spr+s
 dep5d on factors su* z ! rate at :i*   

wat] circulates  ?r\gh ! sy/em (        
und]gr\nd *annelways1 ! am\nt ( heat    
suppli$ at dep?1 & ! ext5t ( dilution ( 
! heat$ wat] by  cool gr\nd wat] ne> !  
surface4    ,illu/ration3 ,black ,gr[l] 
/eam v5ts 7fum>oles71 ,norris ,bas91    
,yell[/one ,national ,p>k1 ,wyom+4      
,illu/ration3 ,mammo? ,hot ,spr+s1      
,yell[/one ,national ,p>k1 ,wyom+4      
,volcano ,environm5ts      ,!re are m   
?an #ejj active volcanoes 7^? t h erupt$
 at  lea/ once )9 record$ hi/ory7 9 !   
_w--#ej ( :i* are 9 !  ,unit$ ,/ates    
7,hawaii1 ,alaska1 ,wa%+ton1 ,oregon1 & 
,cali=nia7--al?\gh _m m are hidd5 "u !  
seas4 ,mo/ active  volcanoes are /rung l
 beads along1 or ne>1 ! m>g9s ( !       
cont95ts1 & m ?an half encircle !       
,pacific ,ocean z a 8,r+ (  ,fire40     
,illu/ration3 ,! di/ribution ( "s ( !   
,e>?'s #ejj active  volcanoes4    ,_m   
volcanoes are 9 & ar\nd ! ,m$it]ranean  
,sea4 ,m\nt ,etna 9  ,sicily is ! l>ge/ 
& highe/ ( ^! m\nta9s4 ,italy's         
,vesuvius  is ! only active volcano on !

 ,european ma9l&4 ,ne> ! isl& (         
,vulcano1 ! volcano ,/romboli has be5 9 
a /ate ( ne>ly cont9u\s1  mild eruption 
s9ce e>ly ,roman times4 ,at night1      
sailors 9 !  ,m$it]ranean c see ! gl[ f 
! fi]y molt5 mat]ial t is  hurl$ into ! 
air4 ,v appropriately1 ,/romboli has be5
 call$ 8!  ligh?\se ( ! ,m$it]ranean40  
,"s volcanoes cr[n isl& areas ly+ ne> ! 
cont95ts1 & o!rs  =m *a9s ( isl&s 9 !   
deep ocean bas9s4 ,volcanoes t5d to     
clu/] along n>r[ m\nta9\s belts :]e     
fold+ & fractur+ (  ! rocks provide     
*annelways to ! surface = ! escape (    
magma4  ,significantly1 major e>?quakes 
also occur along ^! belts1  indicat+ t  
volcanism & seismic activity are (t5    
closely  relat$1 respond+ to ! same     
dynamic ,e>? =ces4    ,9 a typical      
8isl&-arc0 environm5t1 volcanoes lie    
along ! cre/ (  an arcuate1 cru/al ridge
 b\nd$ on its convex side by a deep     
oceanic  tr5*4 ,! granite or granitelike
 lay] ( ! cont95tal cru/  ext5ds b5ea? !
 ridge to ! vic9ity ( ! tr5*4 ,basaltic 

magmas1 g5]at$ 9 ! mantle b5ea? ! ridge1
 rise along fractures  ?r\gh ! granitic 
lay]4 ,^! magmas commonly w be modifi$  
or  *ang$ 9 composition dur+ passage    
?r\gh ! granitic lay] &  erupt on !     
surface to =m volcanoes built l>gely (  
non-basaltic  rocks4    ,illu/ration3   
,m\nt ,s9abung1 ,sumatra 7,by ,j4       
,baylor ,rob]ts 7c7  ,national          
,geographic ,society74    ,illu/ration3 
,isl&-arc environm5t    ,9 a typical    
8oceanic0 environm5t1 volcanoes are     
align$ along !  cre/ ( a broad ridge t  
m>ks an active fracture sy/em 9 !       
oceanic cru/4 ,basaltic magmas1 g5]at$ 9
 ! upp] mantle b5ea?  ! ridge1 rise     
along fractures ?r\gh ! basaltic lay]4  
,because !  granitic cru/al lay] is     
abs5t1 ! magmas are n appreciably       
modifi$ or *ang$ 9 composition & !y     
erupt on ! surface to =m  basaltic      
volcanoes4    ,illu/ration3 ,mauna ,kea 
,volcano1 ,hawaii4    ,illu/ration3     
,oceanic environm5t    ,9 ! typical     
8cont95tal0 environm5t1 volcanoes are   

locat$ 9  un/able1 m\nta9\s belts t h   
?ick roots ( granite or  granitelike    
rock4 ,magmas1 g5]at$ ne> ! base ( !    
m\nta9 root1  rise sl[ly or int]mitt5tly
 along fractures 9 ! cru/4 ,dur+        
passage ?r\gh ! granitic lay]1 magmas   
are commonly modifi$ or  *ang$ 9        
composition & erupt on ! surface to =m  
volcanoes  con/ruct$ ( nonbasaltic      
rocks4    ,illu/ration3 ,m\nt ,adams1   
,wa%+ton4    ,illu/ration3 ,cont95tal   
environm5t                              
,plate-,tectonics ,!ory                 
,illu/ration3 ,9 ! ,pacific ,nor?we/1 ! 
,juan de ,fuca ,plate plunges  b5ea? !  
,nor? ,am]ican ,plate1 locally melt+ at 
dep?2 ! magma  rises to fe$ & =m !      
,cascade volcanoes4    ,accord+ to ! n[ 
g5]ally accept$ 8plate-tectonics0 !ory1 
sci5ti/s believe t ! ,e>?'s surface is  
brok5 into a numb] (  %ift+ slabs or    
plates1 :i* av]age ab\t #ej miles 9     
?ickness4  ,^! plates move relative to  
"o ano!r above a hott]1 deep]1 m  mobile
 zone at av]age rates z great z a few   

in*es p] ye>4 ,mo/ (  ! _w's active     
volcanoes are locat$ along or ne> !     
b\nd>ies  betwe5 %ift+ plates & are     
call$ 8plate-b\nd>y0 volcanoes4  ,h[ev]1
 "s active volcanoes are n associat$ )  
plate b\nd>ies1  & _m ( ^! s-call$      
8intra-plate0 volcanoes =m r\ghly l9e>  
*a9s 9 ! int]ior ( "s oceanic plates4 ,!
 ,hawaiian ,isl&s  provide p]haps ! be/ 
example ( an 8intra-plate0 volcanic *a91
  develop$ by ! nor?we/-mov+ ,pacific   
plate pass+ ov] an inf]r$  8hot spot0 t 
initiates ! magma-g5]ation &            
volcano-=mation  process4 ,! p]iph]al   
areas ( ! ,pacific ,ocean ,bas91 conta9+
 !  b\nd>ies ( sev]al plates1 are dott$ 
by _m active volcanoes t  =m ! s-call$  
8,r+ ( ,fire40 ,! 8,r+0 provides        
excell5t  examples ( 8plate-b\nd>y0     
volcanoes1 includ+ ,m\nt ,/4 ,hel5s4    
,! accompany+ figure %[s ! b\nd>ies (   
li?osph]e plates t  are pres5tly active4
 ,! d\ble l9es indicate zones ( spread+ 
f  :i* plates are mov+ ap>t4 ,! l9es )  
b>bs %[ zones (  und]?ru/+ 7subduction71

 :]e "o plate is slid+ b5ea? ano!r4  ,! 
b>bs on ! l9es indicate ! ov]rid+ plate4
 ,! s+le l9e  def9es a /rike-slip fault 
along :i* plates are slid+ horizontally 
pa/ "o ano!r4 ,! /ippl$ areas indicate a
 "p ( a cont95t1  exclusive ( t along a 
plate b\nd>y1 :i* is und]go+ active     
ext5sional1 compressional1 or /rike-slip
 fault+4    ,illu/ration3 ,major        
tectonic plates ( ! ,e>?4               
,extrat]re/rial ,volcanism              
,illu/ration3 ,m>9] #i imag]y ( ,olympus
 ,mons ,volcano on ,m>s  comp>$ to !    
eight pr9cipal ,hawaiian ,isl&s at !    
same scale  7,m>9] #i ,image ,mosaic1   
,,nasa_/,,jpl74    ,volcanoes &         
volcanism are n re/rict$ to ! planet    
,e>?4 ,mann$  & unmann$ planet>y        
explorations1 beg9n+ 9 ! late #aifj's1 h
  furni%$ graphic evid5ce ( pa/         
volcanism & its products on !  ,moon1   
,m>s1 ,v5us & o!r planet>y bodies4 ,_m  
p\nds ( volcanic  rocks 7 collect$ by   
a/ronauts dur+ ! v>i\s ,apollo lun>  l&+
 missions4 ,only a small fraction ( ^!  

samples h be5  subject$ to exhau/ive    
/udy by sci5ti/s4 ,! bulk ( ! mat]ial is
  /or$ "u controll$-environm5t          
conditions at ,,nasa's ,lun> ,receiv+   
,laboratory 9 ,h\/on1 ,tex41 = future   
/udy by sci5ti/s4    ,f ! #aigf-aigi    
,vik+ mission1 sci5ti/s h be5 able to   
/udy  ! volcanoes on ,m>s1 & _! /udies  
are v reveal+ :5  comp>$ ) ^? (         
volcanoes on ,e>?4 ,= example1 ,m>tian &
  ,hawaiian volcanoes closely resemble  
ea* o!r 9 =m4 ,bo? are %ield  volcanoes1
 h g5tly slop+ flanks1 l>ge multiple    
collapse pits at  _! c5t]s1 & appe> to  
be built ( fluid lavas t h left  num]\s 
fl[ features on _! flanks4 ,! mo/ obvi\s
 diff]5ce  betwe5 ! two is size4 ,!     
,m>tian %ields are enorm\s4 ,!y c gr[   
to ov] #ag miles 9 height & m ?an #cej  
miles across1 9 contra/  to a maximum   
height ( ab\t #f miles & wid? ( #gd     
miles = !  ,hawaiian %ields4            
,voyag]-#b spacecraft images tak5 ( ,io1
 a moon ( ,jupit]1 captur$  volcanoes 9 
! actual process ( eruption4 ,! volcanic

 plumes %[n  on ! image rise "s #fj to  
#ajj miles above ! surface ( ! moon4    
,?us1 active volcanism is tak+ place1 at
 pres5t1 on at lea/ "o  planet>y body 9 
addition to our ,e>?4    ,illu/ration3  
,spacecraft image1 made 9 ,july #aigi1  
%[s volcanic plume  ris+ "s #fj to #ajj 
miles above ! surface ( ,io1 a moon (   
,jupit]  7,voyag] #b photo1 ,,nasa74    
,volcano ,monitor+ & ,rese>*      ,x has
 be5 said t ! sci5ce ( 8volcanology0    
orig9at$ ) !  accurate descriptions ( ! 
eruption ( ,vesuvius 9 ,a4,d4 #gi       
conta9$  9 two lett]s f ,pl9y ! ,y\ng]  
to ! ,roman hi/orian ,tacitus4  ,pl9y's 
lett]s also describ$ ! dea? ( 8 uncle1  
,pl9y ! ,eld]1  :o 0 kill$ 9 ! eruption4
 ,actually1 h[ev]1 x 0 n until !  #ai?  
c5tury t s]i\s sci5tific inquiry into   
volcanic ph5om5a  fl\ri%$ z "p ( ! g5]al
 revolution 9 ! physical & life         
sci5ces1 includ+ ! new sci5ce (         
8geology40 ,9 #ahdg1 an  obs]vatory 0   
e/abli%$ on ! flanks ( ,vesuvius1       
upslope f !  site ( ,h]culaneum1 = ! m  

or less cont9u\s record+ ( !  activity (
 ! volcano t de/roy$ ! city 9 ,a4,d4    
#gi4 ,/ill1  ?r\gh ! fir/ decade ( !    
#bj? c5tury1 ! /udy ( volcanoes by  &   
l>ge cont9u$ to be ( an exp$ition>y     
nature1 g5]ally  und]tak5 aft] !        
eruption _h begun or ! activity _h      
ceas$4    ,illu/ration3 ,! ,u4,s4       
,geological ,survey's ,hawaiian ,volcano
  ,obs]vatory1 on ! crat] rim ( ,kilauea
 ,volcano4    ,p]haps 8mod]n0           
volcanology began 9 #aiab1 :5 ,?omas ,a4
 ,jagg>1 ,head  ( ! ,geology ,dep>tm5t (
 ! ,massa*usetts ,in/itute ( ,te*nology1
  f\nd$ ! ,hawaiian ,volcano ,obs]vatory
 7,,hvo71 locat$ on ! rim (  ,kilauea's 
cald]a4 ,initially support$ by an       
association ( ,honolulu  bus9essm51     
,,hvo began to conduct sy/ematic &      
cont9u\s monitor+  ( seismic activity   
prec$+1 accompany+1 & foll[+ eruptions1 
z  well z a wide v>iety ( o!r           
geological1 geophysical1 & geo*emical   
obs]vations & inve/igations4 ,betwe5    
#aiai & #aidh1 ,,hvo 0  adm9i/]$ by     

v>i\s ,f$]al ag5cies 7,national ,wea!r  
,s]vice1 ,u4,s4  ,geological ,survey1 & 
,national ,p>k ,s]vice71 & s9ce #aidh x 
has  be5 op]at$ cont9u\sly by !         
,geological ,survey z "p ( its  ,volcano
 ,haz>ds ,program4 ,! m ?an #ge ye>s (  
compreh5sive  inve/igations by ,,hvo &  
o!r sci5ti/s 9 ,hawaii h add$           
sub/antially to our und]/&+ ( ! eruptive
 me*anisms ( ,kilauea  & ,mauna ,loa1   
two ( ! _w's mo/ active volcanoes4      
,moreov]1 !  ,hawaiian ,volcano         
,obs]vatory pione]$ & ref9$ mo/ ( !     
commonly  us$ volcano-monitor+ te*niques
 pres5tly employ$ by o!r  obs]vatories  
monitor+ active volcanoes else:]e1      
pr9cipally 9  ,indonesia1 ,italy1       
,japan1 ,lat9 ,am]ica1 ,new ,zeal&1     
,less] ,antilles  7,c>ibbean71          
,philipp9es1 & ,kam*atka 7,u4,s4,s4,r474
    ,:at does 8volcano monitor+0        
actually involve8 ,basically1 x is !    
keep+ ( a detail$ 8di>y0 ( !            
*anges--visible & invisible--9 a        
volcano & its surr\nd+s4 ,betwe5        

eruptions1 visible *anges (  importance 
to ! sci5ti/s w\ld include m>k$ increase
 or decrease  ( /eam+ f kn[n v5ts2      
em]g5ce ( new /eam+ areas2  developm5t (
 new gr\nd cracks or wid5+ ( old ones2  
unusual or  inexplicable )]+ ( plant    
life2 *anges 9 ! color ( m9]al  deposits
 encru/+ fum>oles2 & any o!r directly   
obs]vable1 &  (t5 measurable1 feature t 
might reflect a *ange 9 ! /ate (  !     
volcano4 ,( c\rse1 ! 8di>y0 keep+ dur+  
eruptive activity  pres5ts additional   
tasks4 ,:]ev] & :5ev] !y c d s safely1  
sci5ti/s docum5t1 9 words & on film1 !  
c\rse ( ! eruption 9  detail2 make      
temp]ature measurem5ts ( lava & gas2    
collect !  eruptive products & gases =  
subsequ5t laboratory analysis2 measure  
! heights ( lava f\nta9s or a% plumes2  
gage ! fl[ rate ( a%  ejection or lava  
fl[s2 & c>ry out o!r necess>y           
obs]vations &  measurem5ts to fully     
docum5t & *>act]ize ! eruption4 ,= ea*  
eruption1 su* docum5tation & data       
collection & analysis provide  ano!r    

build+ block 9 con/ruct+ a model ( !    
*>act]i/ic  behavior ( a giv5 volcano or
 type ( eruption4    ,volcano monitor+  
also involves ! record+ & analysis (    
volcanic  ph5om5a n visible to ! human  
eye1 b measurable by precise &          
sophi/icat$ in/rum5ts4 ,^! ph5om5a      
include gr\nd movem5ts1  e>?quakes      
7p>ticul>ly ^? too small to be felt by  
p71  v>iations 9 gas compositions1 &    
deviations 9 local electrical &         
magnetic fields t respond to pressure & 
/resses caus$ by !  subt]ranean magma   
movem5ts4    ,"s common me?ods us$ to   
/udy invisible1 volcano-relat$ ph5om5a  
are bas$ on3    #a4 ,measurem5t ( *anges
 9 ! %ape ( ! volcano--volcanoes        
gradually swell or 8inflate0 9 build+ up
 to an eruption because (  ! influx (   
magma into ! volcano's res]voir or      
8plumb+ sy/em02  ) ! onset ( eruption1  
pressure is imm$iately reliev$ & !      
volcano rapidly %r9ks or 8deflates40 ,a 
wide v>iety ( in/rum5ts1  includ+       
precise _s-levels1 electronic           

8tiltmet]s10 &  electronic-las] beam    
in/rum5ts1 c measure *anges 9 ! slope or
  8tilt0 ( ! volcano or 9 v]tical &     
horizontal di/ances ) a  precision (    
only a few p>ts 9 a million4    #b4     
,precise det]m9ation ( ! location &     
magnitude ( e>?quakes by  a well-design$
 seismic network--z ! volcano inflates  
by ! rise (  magma1 ! enclos+ rocks are 
de=m$ to ! break+ po9t to  accommodate  
magma movem5t4 ,:5 ! rock ultimately    
fails to p]mit  cont9u$ magma asc5t1    
e>?quakes result4 ,by c>efully mapp+ out
 !  v>iations ) "t 9 ! locations & dep?s
 ( e>?quake foci1  sci5ti/s 9 effect c  
track ! subsurface movem5t ( magma1     
horizontally & v]tically4               
,illu/ration3 ,sci5ti/1 we>+ asbe/os    
gloves & gas mask1 samples  volcanic    
gases f active v5t4    #c4 ,measurem5t (
 *anges 9 volcanic-gas composition & 9  
magnetic  field--! rise ( magma high    
into ! volcanic edifice may all[ "s (  !
 associat$ gases to escape along        
fractures1 !reby caus+ !  composition ( 

! gases 7measur$ at ! surface7 to diff] 
f t  usually measur$ :5 ! volcano is    
quiesc5t & ! magma is too deep  to all[ 
gas to escape4 ,*anges 9 ! ,e>?'s       
magnetic field h be5  not$ prec$+ &     
accompany+ "s eruptions1 & su* *anges   
are  believ$ to reflect temp]ature      
effects &_/or ! cont5t ( magnetic       
m9]als 9 ! magma4    ,record+ hi/oric   
eruptions & mod]n volcano-monitor+ 9    
!mselves  are insuffici5t to fully      
det]m9e ! *>act]i/ic behavior ( a       
volcano1 because a "t record ( su*      
in=mation1 ?\gh p]haps long  9 human    
t]ms1 is mu* too %ort 9 geologic t]ms to
 p]mit reliable  pr$ictions ( possible  
future behavior4 ,a compreh5sive        
inve/igation  ( any volcano mu/ also    
include ! c>eful1 sy/ematic mapp+ ( !   
nature1 volume1 & di/ribution ( !       
products ( prehi/oric  eruptions1 z well
 z ! det]m9ation ( _! ages by mod]n     
isotopic  & o!r dat+ me?ods4 ,rese>* on 
! volcano's geologic pa/  ext5ds ! data 
base = ref9$ e/imates ( ! recurr5ce     

int]vals  ( active v]sus dormant p]iods 
9 ! hi/ory ( ! volcano4 ,)  su*         
in=mation 9 h&1 sci5ti/s c con/ruct     
s-call$ 8volcanic  haz>ds0 maps t       
del9eate ! zones ( greate/ risk ar\nd ! 
volcano & t designate :i* zones are     
p>ticul>ly susceptible to  c]ta9 types (
 volcanic haz>ds 7lava fl[s1 a% fall1   
toxic gases1  mudfl[s & associat$       
flood+1 etc474    ,a /rik+ly successful 
example ( volcano rese>* &              
volcanic-haz>d  assessm5t 0 ! #aigh     
publication 7,bullet9 #achc-;,c7 by two 
,geological  ,survey sci5ti/s1 ,dwight  
,cr&ell & ,donal ,mull9eaux1 :o conclud$
  t ,m\nt ,/4 ,hel5s 0 ! ,cascade       
volcano mo/ frequ5tly active 9  ! pa/   
#d1ejj ye>s & ! "o mo/ likely to reawak5
 to erupt1 8444  p]haps be=e ! end ( ?is
 c5tury40 ,_! pr$iction came true :5    
,m\nt ,/4 ,hel5s rumbl$ back to life 9  
,m>* ( #aihj4 ,int]mitt5t  explosions ( 
a% & /eam & p]iodic =mation ( %ort-liv$ 
lava  domes cont9u$ ?r\gh\t ! decade4   
,analysis ( ! volcano's pa/  behavior   

indicates t ?is k9d ( eruptive activity 
may cont9ue =  ye>s or decades1 b ano!r 
cata/rophic eruption l t ( ,may #ah1    
#aihj1 is unlikely to occur soon4    ,on
 #ah ,may #aihb1 ! ,u4,s4 ,geological   
,survey 7,,usgs7 =mally d$icat$ !       
,david ,a4 ,john/on ,cascades ,volcano  
,obs]vatory 7,,cvo7 9 ,vanc\v]1         
,wa%+ton1 9 memory ( ! ,survey          
volcanologi/ kill$ two ye>s  e>li]4 ,?is
 facility--a si/] obs]vatory to !       
,hawaiian ,volcano                      
,obs]vatory--facilitates ! increas$     
monitor+ & rese>* on n  only ,m\nt ,/4  
,hel5s b also ! o!r volcanoes ( !       
,cascade ,range  ( ! ,pacific ,nor?we/4 
,m rec5tly1 9 coop]ation ) ! ,/ate  (   
,alaska1 ! ,,usgs e/abli%$ ! ,alaska    
,volcano ,obs]vatory 9 ,m>*  #aihh4 ,!  
"w be+ done at ^! volcano obs]vatories  
provides  important comp>isons &        
contra/s betwe5 ! behavior ( !  g5]ally 
non-explosive ,hawaiian %ield volcanoes 
& t ( !  g5]ally explosive composite    
volcanoes ( ! ,cascade & ,alaskan       

,p59sula-,aleutian *a9s4                
,volcanoes & ,p      ,volcanoes bo?     
h>ass & help mank9d4 ,z dramatically    
demon/rat$ by  ! cata/rophic eruption ( 
,m\nt ,/4 ,hel5s on ,may #aihj & (      
,p9atubo 9 ,june #aiia1 volcanoes c     
wreak havoc & deva/ation 9 !  %ort t]m4 
,! types ( volcanic & associat$ haz>ds  
are n  describ$ 9 ?is booklet b treat$ 9
 sev]al ( ! publications  li/$ 9        
,sugge/$ ,read+4 ,h[ev]1 x %\ld be      
emphasiz$ t !  %ort-t]m haz>ds pos$ by  
volcanoes are balanc$ by b5efits (      
volcanism & relat$ processes ov]        
geologic "t4 ,volcanic mat]ials         
ultimately break d[n to =m "s ( ! mo/   
f]tile soils on ,e>?1  cultivation ( :i*
 fo/]$ & su/a9$ civilizations4 ,p use   
volcanic products z con/ruction         
mat]ials1 z abrasive & clean+  ag5ts1 & 
z raw mat]ials = _m *emical & indu/rial 
uses4 ,!  int]nal heat associat$ ) "s "y
 volcanic sy/ems has be5  h>ness$ to    
produce geo!rmal en]gy4 ,= example1 !   
electrical  en]gy g5]at$ f ,! ,geys]s   

geo!rmal field 9 nor!rn  ,cali=nia c    
meet ! pres5t p[] consumption ( ! city (
 ,san  ,francisco4    ,! *all5ge to     
sci5ti/s involv$ ) volcano rese>* is to 
mitigate ! %ort-t]m adv]se impacts (    
eruptions1 s t society  may cont9ue to  
enjoy ! long-t]m b5efits ( volcanism4   
,!y mu/  cont9ue to improve ! capability
 = pr$ict+ eruptions & to  provide      
decision mak]s & ! g5]al public ) ! be/ 
possible  in=mation on high-risk        
volcanoes = s\nd decisions on l&-use    
plann+ & public safety4 ,geo-sci5ti/s   
/ill d n fully und]/&  h[ volcanoes     
really "w1 b consid]able advances h be5 
made 9  rec5t decades4 ,an improv$      
und]/&+ ( volcanic ph5om5a provides     
important clues to ! ,e>?'s pa/1 pres5t1
 & possibly its future4                 
,sugge/$ ,read+        ,deck]1 ,rob]t1 &
 ,deck]1 ,b>b>a1 #aihi1 ,volcanoes3     
,w4,h4 ,freeman &    ,company1 ,new     
,york1 #bhe p4 7,revis$ edition74       
,editors1 #aihb1 ,volcano3 9 ! s]ies    
,planet ,e>?1 ,alex&ria1    ,virg9ia1   

,"t-,life ,books1 #agf p4      ,h>ris1  
,s4,l41 #aihh1 ,fire m\nta9s ( ! ,we/3  
,! ,cascade & ,mono    ,lake ,volcanoes3
 ,miss\la1 ,montana1 ,m\nta9 ,press     
,publi%+ ,company1    #cgi p4           
,helik]1 ,*ri/9a1 #aiij1 ,volcanic &    
seismic haz>ds on ! ,isl&    ( ,hawaii3 
,re/on1 ,virg9ia1 ,u4,s4 ,geological    
,survey1 #dh p4      ,macdonald1 ,g4,a41
 #aigb1 ,volcanoes3 ,englewood ,cliffs1 
,new ,j]sey1    ,pr5tice-,hall1 ,inc41  
#eaj p4      ,simk91 ,tom1 ,till+1      
,r4,i41 ,tagg>t1 ,j4,n41 ,jones1 ,w4,j41
 & ,spall1    ,h5ry1 compil]s1 #aihi1   
,?is dynamic planet3 ,_w ,map (         
volcanoes1    e>?quakes1 & plate        
tectonics3 ,u4,s4 ,geological ,survey1  
,re/on1    ,virg9ia1 prep>$ 9 coop]ation
 ) ! ,smi?sonian ,in/itution1           
,wa%+ton1 ,d4,c4 7scale #a3cj1jjj1jjj at
 equator74      ,till+1 ,r4,i41 ,helik]1
 ,*ri/9a1 & ,wright1 ,t4,l41 #aihi1     
,eruptions    ( ,hawaiian volcanoes3    
,pa/1 pres5t1 & future3 ,re/on1         
,virg9ia1    ,u4,s4 ,geological ,survey1

 #ed p4      ,till+1 ,r4,i41 ,top9ka1   
,lyn1 & ,swanson1 ,d4,a41 #aiij1        
,eruptions (    ,m\nt ,/4 ,hel5s3 ,pa/1 
pres5t1 & future3 ,re/on1 ,virg9ia1     
,u4,s4    ,geological ,survey1 #ef p4   
7,revis$ edition74      ,till+1 ,r4,i41 
#aiia1 ,monitor+ active volcanoes3      
,re/on1 ,virg9ia1    ,u4,s4 ,geological 
,survey1 #ac p4 7,revis$ edition74      
,wood1 ,c4,a41 & ,ki5le1 ,jurg51 #aiij1 
,volcanoes ( ,nor? ,am]ica3    ,unit$   
,/ates & ,canada3 ,new ,york1 ,cambridge
 ,univ]sity ,press1 #ced p4             
,illu/ration3 ,! port city ( ,/4 ,pi]re 
on ! isl& ( ,m>t9ique2  ,mont ,pele is 9
 ! backgr\nd4 ,9 #aijb1 ?is city 0      
entirely  de/roy$ by pyrocla/ic fl[s2   
ab\t #cj1jjj p di$4    ,illu/ration3    
,z ! ,nation's pr9cipal cons]vation     
ag5cy1 ! ,dep>tm5t ( !  ,int]ior has    
responsibility = mo/ ( our nationally   
own$ public  l&s & natural & cultural   
res\rces4 ,?is includes fo/]+ s\nd  use 
( our l& & wat] res\rces2 protect+ our  
fi%1 wildlife1 &  biological div]sity2  

pres]v+ ! environm5tal & cultural values
  ( our national p>ks & hi/orical       
places2 & provid+ = !  enjoym5t ( life  
?r\gh outdoor recreation ,! ,dep>tm5t   
assesses our  en]gy & m9]al res\rces &  
works to ensure t _! developm5t  is 9 ! 
be/ int]e/s ( all our p by enc\rag+     
/ew>d%ip  & citiz5 p>ticipation 9 _!    
c>e4 ,! ,dep>tm5t also has a major      
responsibility = ,am]ican ,indian       
res]vation communities & =  p :o live 9 
isl& t]ritories "u ,u ,s adm9i/ration   
,u4,s4 ,geological ,survey    ,in=mation
 ,s]vices    ,p4,o4 ,box #bebhf         
,d5v]1 ,,co #hjbbe                ,=    
sale by ! ,u4,s4 ,gov]nm5t ,pr9t+ ,(fice
  ,sup]9t5d5t ( ,docum5ts1 ,mail ,/op3  
,,ssop1 ,wa%+ton1 ,,dc #bjdjb-icbh      
,u4,s4 ,,gov]nm5t ,,pr9t+ ,,(fice3 #aiif
 #dba-bha                               
,transcrib]'s ,notes      --,reta9$     
publication in=mation f ! pr9t$ edition3
 ?is e,book    is public-doma9 9 !      
c\ntry ( publication4    --,9 ! text    
v]sions only1 text 9 italics is delimit$

 by    und]scores4    --,9 ! ,,ascii    
v]sion only1 subscript$ numb]s are      
prec$$ by    und]score & delimit$ by    
brackets4