Sciency Thoughts: Magnitude 4.5 Earthquake on Big Island, Hawaii.

The United States Geological Survey recorded a Magnitude 4.5 Earthquake at a depth of 16.8 km on te northern part of Big Island, Hawaii, slightly before 6.25 am local time (slightly before 4.25 pm GMT) on Thursday 7 August 2014. This was a large quake for Hawaii, and was felt across much of Big Island, as well as on parts of the neighbouring island of Maui. There are no reports of any injuries, though minor damage to buildings has been reported in places.

The approximate location of the 7 August 2014 Big Island Earthquake. Google Maps.

The islands of Hawaii have formed as a result of hotspot volcanism, with the hotspot currently located under Big Island, Hawai'i, and each of the other islands being the result of previous activity from the same hotspot, with the oldest Islands in the northwest and newest in the southeast. A volcanic hotspot is an area where magma from deep inside the Earth is welling up through the overlying plate (in this case the Pacific) to create volcanism at the surface. Volcanoes move as they erupt, swelling as magma enters their chambers from bellow, then shrinking as that magma is vented as lava. The movements of a group of volcanoes close to one another can place considerable strain on layered rocks, and the islands of Hawai'i, and in particular Big Island, are very prone to Earthquakes, though these tend to be small and frequent rather than large, rare and destructive.

Witness accounts of quakes can help geologists to understand these events and the rock structures that cause them. If you felt this quake (or if you were in the area but did not, which is also useful information) you can report it to the USGS here.

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