Just hours after agreeing to pay $4 million in penalties for the massive Aliso Canyon gas leak, SoCal Gas’ parent company announced the utility’s chief executive is being replaced as part of a major corporate shakeup.

Dennis Arriola, 55, who was named chief executive of SoCal Gas in 2013, will be reassigned to a post as executive vice president of corporate strategy and external affairs at parent Sempra Energy of San Diego, effective Jan. 1, according to a Sempra announcement Tuesday afternoon.

Replacing Arriola as chief executive of SoCal Gas in January will be Patricia Wagner, 54, who is currently chief executive and president of Sempra U.S. Gas & Power. Wagner joined SoCal Gas in 1995 and has since held several executive positions at the utility and at parent Sempra.

This transition is part of a major corporate shakeup announced by Sempra Tuesday afternoon as part of what the company termed the “ongoing leadership development and succession planning process.” Most of the other changes involve C-suite executives at Sempra’s San Diego headquarters.

Earlier Tuesday, SoCal Gas agreed to pay $4 million in penalties and pleaded no contest to one misdemeanor charge of failing to properly notify state and local authorities of the Aliso Canyon gas leak when it began last Oct. 23, according to a press release from the office of Los Angeles County District Attorney Jackie Lacey. The agreement settles a criminal case that county prosecutors were preparing against downtown-based SoCal Gas for its role in what became the nation’s largest gas leak to date.

The $4 million settlement includes up to $1.5 million in costs to install infrared methane leak detection systems, $307,500 in penalties and fines and $246,673 to cover costs incurred by county investigators and emergency response personnel.

Public policy and energy reporter Howard Fine can be reached at hfine@labusinessjournal.com. Follow him on Twitter @howardafine.