(CNN) -- Torrential rains washed long-buried landmines onto a heavily traveled highway near Chile's border with Peru this week.
No one was injured, but activists say the incident is a reminder of the risks such explosive devices pose.
"They are a constant threat. ... This is just reinforcing the need for all governments to clear all contaminated land, or seek assistance in doing so if you're struggling to clear it," said Kate Wiggans, a spokeswoman for the Geneva-based International Campaign to Ban Landmines.
In the 1970s, Chile placed mines along the South American nation's borders with Peru, Argentina and Bolivia as regional tensions rose during Gen. Augusto Pinochet's military dictatorship, which lasted until 1990.
Decades later, more than 120,000 antipersonnel mines remain in Chile, according to the Chilean nonprofit Centro Zona Minada (Mined Zone Center).
This week's appearance of landmines on the Pan-American Highway forced authorities to close a busy border crossing for two days while teams detonated the explosives.
It wasn't the first time the lingering landmines from Chile's military rule have threatened the population, and it won't be the last, said Elir Rojas Calderon, the center's director.
Government officials must do a detailed evaluation of Chile's minefields and take swifter action to remove the dangerous explosives, Rojas said.
"It has become a critical situation, affecting a very traveled pathway. And this situation is going to repeat itself. Every year this happens, and it's something that can be controlled and prevented," he said.
Chilean officials have pledged to clear all the country's landmines by 2020.
"The problem that we have is that it's very difficult work," Defense Minister Andres Allamand told CNN Chile this week, noting that many devices are located in remote, high-altitude areas that are difficult to access.
Landmines are a global problem extending far beyond the South American country's borders, Wiggans said.
Floodwaters have also pushed landmines to the surface in Pakistan and Cambodia, Wiggans said. And they've made some mines sink farther underground, making them more difficult to detect.
But that doesn't make them any less dangerous, Wiggans said.
"The only way that you can say that this field is safe is if every single inch of that field has been checked by human beings. ... It's very time consuming and costly," Wiggans said. "Quite often governments won't clear the land. They think, 'oh, the mines are miles away, no one is every going to get hurt by them.'"
In 2010, landmines injured or killed 4,191 people, a 5% increase from the previous year, according to an International Campaign to Ban Landmines report issued late last year. Globally, tens of thousands of victims are living with injuries caused by landmines, Wiggans said, and many of them are seriously maimed and living in poor countries with limited infrastructure and resources to support them.
Roughly 80% of the world's countries have signed on to an international treaty banning landmines. Wiggans said other nations have stopped producing the mines, but haven't signed it, including the United States and China.