Hazard Vulnerability Assessment
Earthquakes:
General Information index.
Also see current earthquake
mitigation measures.
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Earthquakes are relatively infrequent but not uncommon in North Carolina.
Earthquakes are also unpredictable. From 1568 to 2001, 159 earthquakes have occurred in North Carolina. Alexander
County has experienced at least one earthquake and has been in proximity to
others.
While no significant damages have ever been recorded in Alexander County, the proximity to earthquake faults makes Alexander County, as well as all the municipalities vulnerable to such damages. The charts and images below depict recent history. The entire county, including the municipalities are vulnerable, as is the entire population. |
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Note: An Earthquake's severity is
expressed in both magnitude and intensity. The two terms are sometimes confused
for one another. Magnitude is related to the amount of seismic energy released
at the hypocenter of an earthquake. It is measured using the Richter Magnitude
Scale.
Intensity is based on the observed effects on the earth's surface such as ground
shaking or a building moving. These effects vary according to your location
relative to the epicenter. Intensity is measured using the Modified Mercalli
Intensity Scale.
The following is an abbreviated description of the 12 levels of Modified Mercalli intensity.
| I. | Not felt except by a very few under especially favorable conditions. |
| II. | Felt only by a few persons at rest, especially on upper floors of buildings. Delicately suspended objects may swing. |
| III. | Felt quite noticeably by persons indoors, especially on upper floors of buildings. Many people do not recognize it as an earthquake. Standing motor cars may rock slightly. Vibration similar to the passing of a truck. Duration estimated. |
| IV. | Felt indoors by many, outdoors by few during the day. At night, some awakened. Dishes, windows, doors disturbed; walls make cracking sound. Sensation like heavy truck striking building. Standing motor cars rocked noticeably. |
| V. | Felt by nearly everyone; many awakened. some dishes, windows broken. Unstable objects overturned. |
| VI. | Felt by all, many frightened. Some heavy furniture moved; a few instances of fallen plaster. Damage slight. |
| VII. | Damage negligible in buildings of good design and construction; slight to moderate in well-built ordinary structures; considerable damage in poorly built or badly designed structures; some chimneys broken. |
| VIII. | Damage slight in specially designed structures; considerable damage in ordinary substantial buildings with partial collapse. Damage great in poorly built structures. Fall of chimneys, factory stacks, columns, monuments, walls. Heavy furniture overturned. |
| IX. | Damage considerable in specially designed structures; well-designed frame structures thrown out of plumb. Damage great in substantial buildings, with partial collapse. Buildings shifted off foundations. |
| X. | Some well-built wooden structures destroyed; most masonry and frame structures destroyed with foundations. Rail bent. |
| XI. | Few, if any (masonry) structures remain standing. Bridges destroyed. Rails bent greatly. |
| XII. | Damage total. Lines of sight and level are distorted. Objects thrown into the air. |
Recent Earthquake history in North Carolina:
| March 5, 1958 Wilmington, NC |
Intensity:
V (five) Magnitude: 0 Damage: Shocks transpired along the coast rolling people out of bed and shaking houses. |
| 1987 North Carolina/Tennessee border |
Magnitude
4.2 Largest to occur in the Southeast that year. |
| June 14, 1997 Henderson County, NC |
Magnitude
2.5, Small earthquake Damage: None reported |
| June 5, 1998 Mooresville, NC |
Magnitude
3.2, Small earthquake Damage: None reported |
![[nc fault zone map]](qu1.gif) |
| A map showing geological and seismic
information for North Carolina. (Image courtesy: North Carolina Geological Survey) |
** Potential Economic Impact in Alexander County (including Taylorsville) from a greater than 6.0 (Richter scale) earthquake
| Structural Damage | $56,330,000 |
| Non - structural (i.e. power distribution systems, etc.) | $179,470,000 |
| Contents | $74,670,000 |
| Lost inventory | $3,930,000 |
| Relocation losses (cost of relocating population) | $57,640,000 |
| Capital losses | $26,200,000 |
| Wages lost | $31,440,000 |
| Retail income losses | $22,270,000 |
| Total Potential Losses | $451,192,000 |
Source
** HAZUS Information Data base - FEMA - Dunn and Bradstreet 1994. Adjusted to
2002 by 31%. Worst case scenario.