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A network of quake-sensing devices has captured how last month’s 6.2 shake was felt around the country. Kiwi company Jenlogix operates a network of Palert units that can be triggered by the P-waves that earthquakes send out before the more destructive S-waves arrive.
For its users – which range from councils, universities and district health boards to ports and power companies – the data these devices instantly fire out could offer a brief but critical window to activate emergency shut-downs. When 2016's Kaikoura Earthquake struck, one Wellington user received 19 seconds warning time before the shaking began. The Jenlogix-designed system also quickly produced Shake Maps that illustrated how ground acceleration varied around the country.
In last month’s case, the first Shake Map was created, even before all of the Wellington units triggered, and showed the shaking coming through from the north. Subsequent maps showed the quake rolling through and down to the South Island. Jenlogix business development manager Keith Swasbrook noted that the system didn't need to know the energy produced by a quake, or even its epicentre, to operate. "This means the system provides very timely information that companies can use in their emergency management processes, such as where should they send engineers first to check on faults."
Further, the system sent out SMS messages and email alerts to individuals or groups to let them know the ground acceleration of the units. This map - constructed from triggered devices two minutes after the quake - shows the varying shaking force around Wellington. "Some of the units have been placed in schools near the rail line, where the school benefits from these messages as well as KiwiRail for the level of ground movement of the track."
The units all streamed data to a central server, but also had triggers than could activate local emergency systems – such as stopping a lift at the next floor and open the doors, or turning off a gas supply. The data was also made available to others such as GeoNet and Rapid Alert system of KiwiRail.