Wellington - Residents in the Solomon Islands' southeast were warned to stay indoors on Monday to avoid showers of ash from a volcanic eruption.Officials said a lack of scientific equipment made it difficult to monitor the situation on Tinakula island, which lies just north of Vanuatu where 11 000 people were evacuated last month following an eruption on Ambae island.While the Vanuatu government decided on Friday that the situation on Ambae had settled and people could return home, Solomon Islands officials said they had no indication how long the eruption on Tinakula would continue.Although Tinakula is uninhabited, about 10 600 people live on the neighbouring Santa Cruz islands."Authorities do not have a scientific way to monitor the situation and determine when it will end," the Solomon Islands Broadcasting Corporation (SIBC) quoted National Disaster Management Office director Loti Yates as saying.Yates said ashfall on nearby communities and the impact on air travel were the main concerns. An aviation warning has been issued for the Santa Cruz Islands."As much as possible, people need to stay indoors," he said, while downplaying the significance of the eruption."From what we know currently, the danger of the volcano's impact on Santa Cruz is very small or very limited," he said.Tinakula, which is frequently active, once had a population of about 130 until an eruption in 1971 forced their permanent evacuation.