What is up with these electric power explosions?

Two electric power explosions with almost the same set of circumstances and outcome less than a month apart in two widely varying locations are really freaky. The first happened in downtown Vancouver, British Columbia, on December 23, 2009 ("WorkSafeBC investigates Vancouver hydro explosion", CBC News, http://www.cbc.ca/canada/british-columbia/story/2009/12/24/bc-hydro-explosion-worksafe-investigation.html). This one sent three BC Hydro workers who were working in the underground power vault to hospital. Photographs of the aftermath of the explosion are found on this NowPublic page. The second explosion happened in downtown Honolulu, Hawaii, on January 14, 2010 and sent the two Hawaiian Electric Company employees who were working in the underground power vault to hospital. The Honolulu explosion also knocked out power to over a thousand customers according to this KITV.com report ("Power Restored After Downtown Explosion", January 14, 2010, http://www.kitv.com/news/22238764/detail.html).