The number of traffic jams nearly doubled in Osaka Prefecture shortly after a strong earthquake rocked the metropolitan area last month, according to analysis by Yahoo Japan Corp.
The number of clogged roads started to rise an hour after the magnitude 6.1 quake hit northern Osaka at 7:58 a.m. on June 18 and increased nearly twofold at about 11 a.m., according to the analysis, which used data from June 4 and 11 as a base figure.
Yahoo Japan analyzed the situation based on vehicle running speeds using their car navigation app.
The analysis released Monday revealed traffic jams were seen not only in the inner urban area but also in the suburbs, including relatively minor roads that do not usually get congested.
Yahoo Japan believes the heavy traffic was due to the quake's occurrence during rush hour, the closure of expressways and suspension of train services.
The number of clogged roads gradually decreased in the afternoon and returned to nearly normal by around 10 p.m., meaning that traffic jams caused by the quake lasted for about 14 hours, according to the study.
Four people died in the quake, including a 9-year-old girl who was crushed under a concrete wall that collapsed on her as she was walking to school.
The quake registered a lower 6 on the Japanese seismic intensity scale of 7 — the highest level in Osaka Prefecture since the weather agency started full-fledged observations in 1923.