The K-index, and by extension the Planetary K-index, are used to characterize the magnitude of geomagnetic storms.
Kp is an excellent indicator of disturbances in the Earth's magnetic field and is used by SWPC to decide whether geomagnetic alerts and warnings need to be issued for users who are affected by these disturbances.
Earth is currently inside a stream of solar wind flowing from a massive coronal hole on our Sun which is facing Earth, see dark areas on the image below.
This is the 2nd G1-class geomagnetic storm to impact Earth in the last few days after another coronal hole caused a G1-class geomagnetic storm on Sept the 7th and 8th.
The coronal activity on the Sun and the two geomagnetic storms have coincided with a flurry of seven major quakes to impact the Pacific Ring Of Fire, coincidence?
GEOMAGNETIC STORM IN PROGRESS: Right now, G1-class geomagnetic storms are sparking bright auroras around the Arctic Circle as a stream of high-speed solar wind buffets Earth's magnetic field.
Originally, NOAA forecasters thought the stream might cause a G2-class geomagnetic storm, but now it appears set to peak as a weaker G1-class disturbance.
M 6.3 - 202km WNW of Ile Hunter, New Caledonia
Another major quake struck the Pacific Ring Of Fire last night bringing the total to seven in five days to hit the volatile area.
Last nights quake was the 7th major quake of September and the 84th of 2018.
All the major quakes in September have struck during the coronal activity on our Sun