People search through debris in a residential area following an earthquake and tsunami in Palu, Central Sulawesi, Indonesia. Antara Foto/Darwin Fatir/via REUTERS

BERLIN (Reuters) - Tsunami warnings to the local population of quake-hit Sulawesi island failed on the “last mile”, causing many to be surprised by waves as high as six meters (20 feet), according to a German research center that developed a warning system used by Indonesia.

Questions have arisen over why warning systems appeared to have failed after a 7.5 magnitude earthquake off the coast of Indonesia on Friday. The confirmed death toll from the quake and subsequent tsunami had reached 844 by Monday and was expected to rise further.

“The problem was the communication between local authorities and people, for example on the beach, such as in Sulawesi,” Joern Lauterjung, Director Geoservices at GFZ, told Reuters TV.

Germany provided a warning system developed by GFZ to Indonesia after a devastating tsunami killed 226,000 people in 2004.

Lauterjung said that system worked as planned, predicting waves up to three meters northwest of Sulawesi.

“If you look at the entire warning chain from the creation of a warning signal up to the last mile, as we call it, up to the local population in danger, there was a problem there,” he said.

“For example, it appears sirens did not work and there were no warnings via loudspeaker vans from police to the local population,” he added.