While working on another project I received a call from a relative asking if I had felt a large Earthquake that shook them awake in Delaware, and has been felt as far north as New Hampshire. We live in the Atlanta area, and while I didn’t feel the temblor, I am currently unaware if there were any significant movement as far south as the Greater Atlanta area:

Quake Listed at 5.9 Rattles East Coast From North Carolina to New York

The quake that struck the East Coast comes as no surprise; there has been significant earthquake activity on the East Coast before, however, even though the 7.3 quake that struck Charleston, South Carolina in 1886 caused a significant loss of life and property damage, it has largely escaped the public’s attention in this new age of geological activity. I worry that this could be a “pre-quake” or alternatively, as a direct consequence of today’s quake, could awaken the fault mechanism that caused the quake of 1886:

Charleston, South Carolina
1886 September 01 02:51 UTC (local August 31)
Magnitude 7.3
Intensity X

Largest Earthquake in South Carolina

Isoseismal Map

• Damage Photos
• Damage Photos from the USGS Photographic Library

This is the most damaging earthquake to occur in the Southeast United States and one of the largest historic shocks in Eastern North America. It damaged or destroyed many buildings in the old city of Charleston and killed 60 people. Hardly a structure there was undamaged, and only a few escaped serious damage. Property damage was estimated at $5-$6 million. Structural damage was reported several hundred kilometers from Charleston (including central Alabama, central Ohio, eastern Kentucky, southern Virginia, and western West Virginia), and long-period effects were observed at distances exceeding 1,000 kilometers.

Effects in the epicentral region included about 80 kilometers of severely damaged railroad track and more than 1,300 square kilometers of extensive cratering and fissuring. Damage to railroad tracks, about 6 kilometers northwest of Charleston, included lateral and vertical displacement of tracks, formation of S-shaped curves and longitudinal movement.

The formation of sand craterlets and the ejection of sand were widespread in the epicentral area, but surface faulting was not observed. Many acres of ground were overflowed with sand, and craterlets as much as 6.4 meters across were formed. In a few locations, water from the craterlets spouted to heights of about 4.5 to 6 meters. Fissures 1 meter wide extended parallel to canal and stream banks. A series of wide cracks opened parallel to the Ashley River, and several large trees were uprooted when the bank slid into the river.

At Summerville, a small town of 2,000 population, 25 kilometers northwest of Charleston, many houses settled in an inclined position or were displaced as much as 5 centimeters. Chimneys constructed independently of the houses commonly had the part above the roofline thrown to the ground. Many chimneys were crushed at their bases, allowing the whole chimney to sink down through the floors. The absence of overturning in piered structures and the nature of the damage to chimneys have been interpreted as evidence that the predominant motion was vertical.

The meizoseismal area of MM intensity X effects is an elliptical area, roughly 35 by 50 kilometers, trending northeast between Charleston and Jedburg and including Summerville. Middleton Place, about in the center of this ellipse, is at the southeast end of a zone (perhaps 15 kilometers long) of microearthquake activity that still continues today. This seismic activity may be a continuation of the 1886 aftershock series.

The intraplate epicenter of this major shock is not unique for large earthquakes in the Eastern and Central United States. Other intraplate earthquakes include those at Cape Ann, Massachusetts (1755), and New Madrid, Missouri (1811-1812). Earthquakes occurring along boundaries of plates (e.g., San Francisco, 1906) are well understood in terms of plate tectonics, but those occurring within plates are not similarly understood. This problem still is being studied more than 100 years after the earthquake.

This earthquake was reported from distant places such as Boston, Massachusetts; Milwaukee, Wisconsin, Chicago, Illinois; Cuba and Bermuda. LINK TO USGS

For those that live in the South Carolina area, we extend a warning that they should be prepared for a quake in their area that could be devastating – but also caution that the mechanism(s) that causes these quakes on the East Coast is still not well understood in the scientific community, so be prepared but do not panic! The likelihood of this being a “pre-quake,” or today’s quake reactivating the mechanism that caused the quake of 1886 is remote but still remains a viable possibility. To be forewarned is to be prepared, and again, in this age of increasing seismicity, people living in areas that are prone to earthquakes should use common-sense and caution, invest in food and water storage and prepare for anything that nature might throw their way.

In the interests of providing a timely commentary that is relevant to today’s earthquake we will provide a link to yesterday’s Colorado Earthquake and will update this article later today or tomorrow and explain why the quake in Colorado is far more understood than that which occurred today – and why we can expect more temblors in the same general area area.

Largest Colorado Quake Since 1967 Shakes Homes

Editors Note:

Because of the large amount of content that was involved in analyzing Colorado’s recent 5.3 Earthquake, we had to address that issue in a separate post. We apologise for any inconvenience that this might have caused. You can read that article here:

What Caused Colorado’s 5.3 Earthquake on August 23rd And Other Unrelated U.S. Seismic Activity?