Jan 04 2021 31 mins 11
Two weeks after Valentine's Day, 2001, a magnitude 6.8 earthquake struck the south sound region of Washington state near where the Nisqually River empties into Puget Sound. It was nearly 11 a.m. on a Wednesday, and the state legislature was in full swing. The violent tremors lasted nearly a minute, rocking the state capital of Olympia and the nearby cities of Lacey, Tumwater, Nisqually, DuPont, and Shelton. The shocks registered as far away as Oregon, Idaho, and Canada.
Legislative staffers either took cover as best they could in a marble and sandstone building, or ran screaming into the streets as the iconic dome of the century-old capitol building cracked, splintering a support buttress. If it weren't for previous earthquake-resistance work, the dome might have collapsed, pulled down from within by the weight of the Volkswagen-sized chandelier in the capitol rotunda, which ominously swayed back and forth for hours after the tremor.
Property damage estimates up and down western Washington totaled in the billions. One person died of a heart attack and nearly four hundred were injured. This was a large earthquake that hit in the Puget Sound region…but it wasn't the first. Not by a long shot.
My father, the senior fearless field guide, told me about a new show on NatGeo, available through Disney Plus, called X-Ray Earth. It offers an unprecedented look inside our planet using underground monitoring sensors scattered across the world. Many of those sensors - some 1,100 in fact - are located here in the Pacific Northwest and just off our coastline. The data provided by these sensors confirms what scientists have been warning us about for years. The entire western edge of North America sits atop a geologic hotspot known as a subduction zone, which ultimately is what puts us most at risk for earthquakes.
But let's back up just a bit…say you don't know anything about geology. Or geography. Or even earth's northwestern hemisphere, for that matter. Here's a quick and dirty summary of how plate tectonics work to help prime our discussion on earthquakes today.
Geology 101
Millions of years ago, the surface of the earth consisted of one enormous land mass called Pangea, and an even more enormous body of water called Panthalassa. All of this land and water floated atop a planetary lake of magma (which is basically superheated, molten rock and metal - we call it lava once it reaches the surface). The land and water made up the earth's crust, and the magma just beneath it made up what's called the earth's mantle.
The supercontinent Pangaea in the early Mesozoic Era.
Boiling hot rock and metal tends to be very active, generating gasses and building pressure in various places, and swirling around the planet as it spins on its axis in space. Because of these forces, weak spots along the earths crust, both underwater and on land would crack open to allow a release of this pressure, and hot magma would come to the surface, sometimes building mountains over eons and sometimes just pushing open the crack wider and wider as the lava cooled and became new land.
After millions of years of this geologic activity, those cracks eventually reached the ocean and water rushed in, separating the land mass into two pieces slowly drifting apart. This was happening in countless places all over Pangea and under the ocean, and over time those land masses that drifted apart became the continents that we recognize on earth today. It all happens so slowly that it can barely be registered as movement…but rest assured, it is happening. And under the surface, the boiling ocean of magma is just as active as ever.
Eventually, the chunks of land floating around on the magma were called tectonic plates and given names. The mammoth plate resting under the Pacific Ocean is called the Pacific Plate, and the one supporting North America is called the North American Plate. Here in Washington, we live atop a tiny shard of one of those two plates ...
Legislative staffers either took cover as best they could in a marble and sandstone building, or ran screaming into the streets as the iconic dome of the century-old capitol building cracked, splintering a support buttress. If it weren't for previous earthquake-resistance work, the dome might have collapsed, pulled down from within by the weight of the Volkswagen-sized chandelier in the capitol rotunda, which ominously swayed back and forth for hours after the tremor.
Property damage estimates up and down western Washington totaled in the billions. One person died of a heart attack and nearly four hundred were injured. This was a large earthquake that hit in the Puget Sound region…but it wasn't the first. Not by a long shot.
My father, the senior fearless field guide, told me about a new show on NatGeo, available through Disney Plus, called X-Ray Earth. It offers an unprecedented look inside our planet using underground monitoring sensors scattered across the world. Many of those sensors - some 1,100 in fact - are located here in the Pacific Northwest and just off our coastline. The data provided by these sensors confirms what scientists have been warning us about for years. The entire western edge of North America sits atop a geologic hotspot known as a subduction zone, which ultimately is what puts us most at risk for earthquakes.
But let's back up just a bit…say you don't know anything about geology. Or geography. Or even earth's northwestern hemisphere, for that matter. Here's a quick and dirty summary of how plate tectonics work to help prime our discussion on earthquakes today.
Geology 101
Millions of years ago, the surface of the earth consisted of one enormous land mass called Pangea, and an even more enormous body of water called Panthalassa. All of this land and water floated atop a planetary lake of magma (which is basically superheated, molten rock and metal - we call it lava once it reaches the surface). The land and water made up the earth's crust, and the magma just beneath it made up what's called the earth's mantle.
The supercontinent Pangaea in the early Mesozoic Era.
Boiling hot rock and metal tends to be very active, generating gasses and building pressure in various places, and swirling around the planet as it spins on its axis in space. Because of these forces, weak spots along the earths crust, both underwater and on land would crack open to allow a release of this pressure, and hot magma would come to the surface, sometimes building mountains over eons and sometimes just pushing open the crack wider and wider as the lava cooled and became new land.
After millions of years of this geologic activity, those cracks eventually reached the ocean and water rushed in, separating the land mass into two pieces slowly drifting apart. This was happening in countless places all over Pangea and under the ocean, and over time those land masses that drifted apart became the continents that we recognize on earth today. It all happens so slowly that it can barely be registered as movement…but rest assured, it is happening. And under the surface, the boiling ocean of magma is just as active as ever.
Eventually, the chunks of land floating around on the magma were called tectonic plates and given names. The mammoth plate resting under the Pacific Ocean is called the Pacific Plate, and the one supporting North America is called the North American Plate. Here in Washington, we live atop a tiny shard of one of those two plates ...
