EARTHQUAKES have once again struck around the world last night and this morning, with some major tremors touching down in the USA and Philippines.
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| Earthquakes today - Huge earthquakes touch down in Alaska and the USA |
Alaska has once again been at the mercy of major tremors, as the frequently earthquake struck region is forced the bear the brunt once again.
Today’s activity has been occurring on the surface of the Earth’s crust, where even smaller tremors can cast a much larger presence.
Most of the activity has once again taken place around the Pacific ‘Ring of Fire’ where a significant amount the world’s earthquakes occur daily.
Normally, this activity is no cause for concern, but today’s higher magnitude and surface locations are painting a slightly more alarming picture.
Earthquakes in the USA
Alaska’s city of Kaktovik has once again been placed near to the latest earthquake activity, with a total of six happening in the region so far.
While most of the earthquakes are at a minor magnitude of 2.9 to 3.1, they took place at an average depth of 0.1km.
There was similar activity in the central United States as well, with three separate minor but shallow tremors in Oklahoma.
Two of the earthquakes were at a magnitude of 3.1, and another at 2.8, all at a depth of 5km.
Earthquakes take place at varying depths, but when they are deeper, the effects on the surface are limited.
The United States Geological Service (USGS)explained why the surface waves feel much stronger than they are.
The service said: “When waves reach the surface of the ground, most of their energy is reflected back into the crust.
“Thus, the surface is affected simultaneously by upward and downward moving waves.”
“After a few shakes, a combination of two kind of waves is felt in ground shaking.
“A considerable amplification of shaking occurs near the surface.
“This surface amplification enhances the shaking at the surface of the Earth.”
So while the magnitude was low, relative surface depth made the tremors seem much larger.
Earthquakes in South East Asia
The Philippines, set at the foot of the Ring of Fire, has had some of the most significant activity today.
A total of two earthquakes took place on the island chain, one magnitude 5 45km northeast of San Isidro, and another magnitude 4.4 off the coast of Lais.
The large magnitude 5 was 35km deep, likely just felt as a rumble on the surface.
The other 4.4 magnitude was 140km deep and probably not felt at all on the surface.
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