Monday, December 17, 2018

The First Great Quake, and a Modern East Tennessee Quake

 Sunday December 16th marked the 207th anniversary of the first of the New Madrid earthquakes.  The quake was unprecedented in its magnitude and reach across a wide area of the country.  Eyewitness accounts detail catastrophic effects in the area of the epicenter.  For example this account by Daniel Bedinger. A traveller down the Mississippi river at the time of the quake. To see the account visit this link:Daniel Bedinger account.  As a reminder of our current siesmicity and what it can do we had last week a magnitude 4.4 earthquake in the East Tennessee seismic zone.  This earthquake was felt over a wide area and reminded people we live in a seismically active area.  For more information on this modern earthquake visit this linkMagnitude 4.4 East Tennessee Earthquake.

Wednesday, February 7, 2018

The Big One

On this day 206 years ago the last and greatest of the New Madrid earthquakes occurred.  It was noted by many and described as the hard shock.  It was felt across the eastern United States and noted as a distinct earthquake and not an aftershock of the earlier New Madrid earthquakes.  This earthquake spawned the myth that the Mississippi river moved backward during the quake. In fact when the fault ruptured near New Madrid it shoved the river upstream temporarily and then sloshed back the opposite direction.  Here is an eyewitness account of that quake as it was experienced at New Madrid.
Matthias Speed account

Speed's account gives a detailed description of what the earthquake did at New Madrid.  Until the modern era many aspects of his account were  believed to be exaggerations.  When seismologists such as Arch Johnston investigated the account they found it to have fidelity to what actually occurred.

Tuesday, January 23, 2018

The Second Great Quake

206 years ago today, the second of the great New Madrid earthquakes occurred.  The second earthquake was not as noticeable as the first quake of December 16 in the area near the epicenter due to the numerous aftershocks that were still occurring in the region. However further away from the epicentral area the second quake was noticed and noted to be a distinct earthquake.  Here is an example of an eyewitness account of the effect of the quake 

This account was from Coshockton, Ohio which was a great distance from the New Madrid seismic zone. It exmplifies the power that the earthquakes manifested even at great distances in the eastern United States.
As a coincidence today there was a magnitude 7.9 earthquake in the ocean off of Alaska.  This earthquake caused no damage but shows that earthquakes are always occurring and stirring the earth.  For more information visit this link: Alaskan Earthquake