People share their theories on source of 'big bang' heard across Liverpool The sound was heard far and wide this morning Get the best local news with our MySefton newsletterInvalid EmailSomething went wrong, please try again later. Sign Up Now When you subscribe we will use the information you provide to send you these newsletters. Sometimes they’ll include recommendations for other related newsletters or services we offer. OurPrivacy Noticeexplains more about how we use your data, and your rights. You can unsubscribe at any time. Thank you for subscribingWe have more newslettersShow meSee ourprivacy notice A loud bang that was heard across the city this morning left many people scratching their heads as to what might have caused it.