In this Sept. 28, 2017 file photo, destroyed communities are seen in the aftermath of Hurricane Maria in Toa Alta, Puerto Rico. Researchers said on April 22, 2021, they are launching a survey of the causes of deaths following the Category 4 storm to clear up questions about a death toll that analysts so far have attributed to factors such as power outages, building failures, and damaged roads. (AP Photo/Gerald Herbert, File)

SAN JUAN, Puerto Rico (AP) — Researchers said Thursday they are launching a survey of the causes of deaths in Puerto Rico following Hurricane Maria to clear up questions about why the toll of the 2017 Category 4 storm was so high.

Studies by George Washington University found an estimated 2,975 excess deaths in the six months in Puerto Rico following Maria — far above the initial official death counts reported by a government that struggled to keep track of those dying, including many elderly in nursing homes without power.

The university’s new study, in collaboration with the University of Puerto Rico, will survey nearly 1,700 people who might have information on those who died and why. Analysts have suggested that power outages, building failures and damaged roads contributed to increased deaths after the storm.

The university said results of the survey will be accompanied by recommendations on how to improve building codes and other standards that could prevent future deaths or injuries.