but I'm not sure at all - it's just a suggestion and may be too general.

"We distinguish between two types of quake-waves; body waves and surface
waves."

www.mgm.monschau.de/seismic/artikel/eng/seisgr.htm

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Note added at 2003-05-16 16:13:23 (GMT)
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Back again, Sandy,. Forget my first suggestion:

They appear to be the effects of P-waves (Primary waves)

\" le onde P producono spostamenti del suolo prettamente verticali (sussultori)\"


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Note added at 2003-05-16 16:13:54 (GMT)
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the link for the above reference is:

http://www.provincia.fi.it/viabilit/terremoti/come_comportar...

It would appear to be the secondary waves (S-waves) or the Rayleigh surface wave type that can produce the up and down (sussultatory) movement, not P-waves which move parallel to the seismic wave (compressional or tensional). The exact technical term "sussultatory" however seems to be very rarely used (at least as evidenced by a Google search) except in translations from Italian.

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Note added at 2003-05-16 16:39:52 (GMT)
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I was just looking at the link Sarah provided and realized that the vertical movement in that case is referring to the soil, not the wave stress itself, which makes sense since a compressional wave would push the soil up, and a tensional wave would allow the soil to fall. So while the wave stress itself is parallel to the wave direction (radiating out from the epicenter), the soil would move either up or down.

Since \"sussultory\" is apparently rare in English, we\'d probably need more context to come up with a good translation.

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Note added at 2003-05-16 16:41:08 (GMT)
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I mean \"sussultatory\" is rare. Ooops!

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Note added at 2003-05-16 16:47:15 (GMT)
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Here\'s what my Italian dictionary has:

2 gio-fis., caratterizzato da oscillazioni in senso verticale provocate da onde sismiche superficiali: \"movimento tellurico s.\"

So based on that definition neither P nor S waves could provoke \"sussultatory\" movement since they are both \"body\" waves, not \"surface\". And unless this definition is inaccurate or incomplete (which it may be), it would appear we\'re talking about Rayleigh-type surface waves.

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Note added at 2003-05-16 16:57:08 (GMT)
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Another dictionary definition of \"sussultorio\":

\"scossa s. di un terremoto\", quella corrispondene all\'arrivo di onde sismiche longitudinali

So this contradicts the other definition since \"longitudinal\" waves are the P-waves. See this site:

http://www.schoolscience.co.uk/content/4/chemistry/findoils/...

Good luck! ;-)

criepi.denken.or.jp/eng/PR/Nenpo/2001E/01seika10.pdf

www2.kobe-u.ac.jp/~uenishi/docs/ Uenishi_Sakurai_EQE_2000.pdf

criepi.denken.or.jp/eng/PR/Nenpo/1996E/96seika10.html

Da quanto descritto su questo sito si tratta di movimenti verticali

http://www.elbasun.com/Spazio_scuola_bis.htm

LE ONDE SISMICHE
Esistono vari tipi di onde sismiche: le onde P o primarie (onde di compressione); le onde S o secondarie; le onde L o superficiali.

Le prime due si propagano all'interno della Terra e, quando giungono in superficie, si registrano come onde sussultorie, caratterizzate cioè da movimenti verticali; le ultime si propagano solo in superficie e sono responsabili delle scosse ondulatorie, prevalentemente orizzontali, che sono spesso la causa principale delle maggiori distruzioni.