<prompt> Translate the following text to EnglishKwa sababu ya hali ya kutoelewana ya milipuko, njia ya kuingia kwenye kreta ya kati inaweza kutofautiana kutoka milipuko moja hadi nyingine milipuko mikubwa ya 1998 ilidumu kwa kipindi cha miezi minane.  <response>: Because of the erratic nature of the eruptions, the approach to the central crater can vary from one eruption to the next serious eruptions in 1998 lasted over a period of 8 months. 