AGS / Geohazards / Land Subsidence / Earthquake Induced
In 1811 and 1812, a series of strong earthquakes rattled northeastern Arkansas. These earthquakes initiated significant liquefaction that drastically changed the ground surface. Land subsidence was one of the major effects of these earthquakes. Large tracts of land subsided during the earthquakes and were flooded with water. Lakes such as Big Lake and St. Francis Lake formed in areas where the land surface has significantly subsided.
Land subsidence can occur in various ways during an earthquake. Movement that occurs along faults can be horizontal or vertical or have a component of both. As a result, a large area of land can subside drastically during an earthquake. Land subsidence can also be caused during liquefaction. Liquefaction can result in the settling and compacting of unconsolidated sediment in an event of a major earthquake. This can result in the lowering of the land surface.