Magnitude 4.7 Earthquake Near Hasaki Causes Anomalies on ASE Submarine Cable
Earthquake near Hasaki
On August 29, 2026, at 18:17 local time, an earthquake of magnitude 4.7 occurred 16 km east-northeast from Hasaki, Japan. This region is known for its high seismic activity, making it important for monitoring submarine data transmission infrastructure. Despite the relatively small magnitude, the event caused local anomalies in the operation of some submarine cables.
Key Cables in the Region
Around 500 km from the epicenter are several major submarine cable systems, including:
- Asia Submarine-cable Express (ASE)/Cahaya Malaysia (8148 km, RFS 2012, operators NTT and PLDT), with a land station in Maruyama, Japan, located 128 km from the epicenter.
- Pacific Crossing-1 (PC-1) (21000 km, RFS 1999, operator Pacific Crossing), with an node in Ajigaura, Japan, just 73.1 km from the epicenter.
- EAC-C2C (36500 km, RFS 2002, operator Telstra), also with a node in Ajigaura.
- Taihei (7000 km, RFS 2027, operator Google), with a node in Takahagi, Japan, 104.2 km from the epicenter.
- Asia United Gateway East (AUG East) (8900 km, RFS 2029, operators Amazon Web Services and Arteria), with a node in Wada, Japan, 122.9 km from the epicenter.
- Trans-Pacific Express (TPE) Cable System (17968 km, RFS 2008, operators AT&T and China Telecom), with a node in Maruyama, Japan.
- New Cross Pacific (NCP) Cable System (13618 km, RFS 2018, operators China Mobile and China Telecom), with a node in Maruyama.
Anomalies in Cable Operation
Our measurements have revealed significant changes in round-trip time (RTT) on the ASE/Cahaya Malaysia cable. The baseline RTT for this cable is 79.2 ms, but after the earthquake, it increased to 276.0 ms, representing a jump of 196.7 ms, more than two and a half times the standard deviation. For other cables in the area, including PC-1, EAC-C2C, Taihei, Tata TGN-Pacific, AUG East, TPE, and NCP, infrastructure has held up and is operating normally, confirming their resilience to such events.
Potential consequences
Anomalies on the ASE/Cahaya Malaysia cable may lead to temporary data transmission delays between Japan and other Asian countries, particularly for operators NTT and PLDT. However, due to the availability of alternative routes, such as PC-1, EAC-C2C, and other systems, global internet traffic in the region has not faced critical issues. This underscores the importance of backup infrastructure in seismically active areas.
Monitoring plans
We will continue to monitor the parameters of the submarine cables in the event zone to promptly record any changes. Special attention will be given to ASE/Cahaya Malaysia, where anomalies have already been observed. Additional checks will also be conducted for potential structural damages to the cables and their termination stations. The monitoring data will be regularly updated on our portal.
