ATHENS — Sparks from Greece’s aging electricity grid are responsible for a disproportionate share of the country’s most destructive wildfires, according to preliminary data from Greece’s Arson Crimes Investigation Directorate and evidence from recent fire investigations.

While power infrastructure accounts for only a small share of wildfire incidents, fires sparked by the grid often break out under the most dangerous conditions — during high winds, in periods of heavy electricity demand and often in remote, fire-prone areas — making them more likely to spread rapidly and become catastrophic.

According to the Arson Crimes unit, fires linked to the electricity grid account for about 75 percent of the land burned in Greece this year.