What do the bubbles on the USGS earthquake map represent?

davenn · Mar 8, 2018

Hi all

This morning, another large quake. This time a M 6.8 just offshore of SE New Ireland, PNG

M 6.8 - 20km ENE of Taron, Papua New Guinea

my seismogram

Multi-channel seismogram in a helicorder-style plot, with time rows labeled in UTC and EDT, showing a large seismic event near the top right and sustained noise across the lower rows.

location map

Satellite map of the Bismarck Sea region of Papua New Guinea showing New Ireland and New Britain islands, with a cyan dot and two yellow dots marking earthquake epicentres and red lines marking plate boundaries.

cheers
Dave

scottdave · Mar 8, 2018

What do all of the "bubbles" represent on this map from the USGS site?

Map of Papua New Guinea and the Solomon Sea region with many white and grey circles marking earthquake epicentres, concentrated along the New Guinea and Solomon Islands arcs and the West Melanesia Trench.

davenn · Mar 8, 2018

scottdave said:

What do all of the "bubbles" represent on this map from the USGS site?

lots and lots of quakes over the last x number of years, size of the dot represents magnitude range ... It may say how many years ... let me go look

hmmm doesn't seem to specifically say in the main text, but since they are constantly referring to how many M x.x sized big quakes since 1900, it may well cover all quakes M5 and up since 1900

Ahhh, found the map key

M4.5 and up 1900 - 2015

Dave

What do the bubbles on the USGS earthquake map represent?

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