In an era of pervasive communications through the Internet and smartphones, reliance on the 1970s technology of the fax machine has been blamed in part for a failure to warn residents of a small Japanese island last week as a deadly typhoon moved in. The heavy rains caused mudslides that left 29 people dead and another 18 missing.

Typhoon Wipha was the worst storm to hit Japan in a decade, bringing rains of up to 122.5 millimeters per hour on Oct. 15. The Japan Meteorological Agency issued mudslide warnings for the islands...