Reuters reports ash is so heavy at the airport, planes carrying relief supplies can't yet land.
Ships with supplies are also on the way.
Two people have been confirmed dead, but communications from the island have been limited, so the true extent of the devastation is not yet known.
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Many residents in California are still anxious to hear from loved ones.
"It's really hard, especially with your son out there," said Liberty Latu.
Latu from Redwood City is consumed with worry about her 11-year-old son Gordon, who lives in Tonga. She hasn't spoken to him since last Friday, hours before a massive underwater volcano erupted near the island nation.
The phone and internet were knocked out. Liberty needs to know if Gordon is OK.
"It's really tough, I can't sleep. I stay up and think of him," said Latu.
Pastor Vaka Taimani from the First Tongan Church in San Carlos is also hoping for news about friends and loved ones in Tonga. He knows food and water supplies may be contaminated from volcanic ash.
"We pray that God will help them, the air they're breathing is not clean," said Taimani.
Seslia Langi Pahulu's shipping company in Oakland is stepping up to help. SF Enterprises & Logistics will soon be sending two ships to Tonga full of relief supplies, it's accepting donations from the public at its Mandella Parkway headquarters near the Port of Oakland.
"If anybody has general donations, I'd stick to water, masks, relief goods and I'll ship it," said Pahulu.
She says supplies will eventually be distributed by the Tongan government.
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