A Twitter user took this photo that purports to show serious damage to a building in Napa - a city around three miles (5km) from the epicentre of the earthquake.
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After a cold start on Wednesday, it will be another day of sunshine and showers across many central and eastern parts.
It is claimed that both police and security services, including MI5, have been prevented from vast pools of data on the social media site.
School funding is shooting up the list of voters' priorities as the General Election approaches, according to researchers.