The 1886 

Charleston, South Carolina, EarthquakeA 1986 Perspective 

U.S. GEOLOGICAL SURVEY CIRCULAR 985 
COVER: St. Philip's Anglican Church, Charleston. 
The 1886 Charleston, South Carolina, Earthquai'eA 1986 Perspective 

By Otto W. Nuttli, G. A. Bollinger, and Robert B. Herrmann 

U.S. GEOLOGICAL SURVEY CIRCULAR 985 

1986 
DEPARTMENT OF THE INTERIOR 

DONALD PAUL HODEL, Secretary 

U.S. GEOLOGICAL SURVEY 

Dallas L. Peck, Director 

Rrst printing 1986 

Second printing 1988 

UNITED STATES GOVERNMENT PRINTING OFFICE: 1986 

Free on application to the Books and Open-File Reports Section, 

U.S. Geological Survey, Federal Center, Box 25425, Denver, CO 80225 
FOREWORD 

At 9:50p.m. on August 31, 1886, the accumulated strain in the Earth's crust in the 

Charleston, South Carolina, area reached the 

point where a fault ruptured, causing a major 

earthquake. In the span of about 60 seconds, 

the Charleston earthquake caused 60 deaths, 

numerous injuries, economic losses of $23 million (1978 dollars) and psychological and social 

disruption over an area extending 120 miles 

from the epicenter encompassing communities 

such as Augusta, Georgia, and Aiken, South 

Carolina. Within 6 to 8 minutes, the effects of 

the ground shaking were felt as far away as 

New York City, New York, Chicago, Illinois, 

and St. Louis, Missouri. For the next 30 years, 

more than 400 aftershocks occurred in the 

Charleston area, adding to the damage and social disruption. 

This U.S. Geological Survey publication commemorates the following events: (1) the 100th 

anniversary of the 1886 Charleston, South Carolina, earthquake and the researchers who 

have contributed through the years to improving our understanding of what happened before, during, and after the earthquake and why 

it happened and (2) the 3rd U.S. Conference on 

Earthquake Engineering, convened in Charleston, South Carolina, from August 24 to 27, 

1986, to present the results of recent research 

in geology, seismology, architecture, soils engineering r structural engineering r and social sciences and to encourage the development and 

implementation of improved earthquake preparedness measures throughout the Nation. 

We believe that this publication will increase 

basic understanding of the 1886 Charleston 

earthquake and contribute to short- and longterm earthquake preparedness activities. 

Director 

U.S. Geological Survey 

iii 

PREFACE 

Charleston and the Nation in the 1880's 

By Nancy Buxton 1 and G. A. Bollinger2 

To set the stage for the discussions of the effects of the 1886 shock and to place them in 

the context of their times, we present the following brief overview of the Union, South Carolina, and Charleston at the close of the 19th 

century. 

In 1880, the United States consisted of 38 

States. Colorado was the newest State, having 

joined the Union in 1876. Still to be admitted 

were Arizona, New Mexico, Oklahoma, the 

Dakotas, Washington, Utah, Idaho, Montana, 

and Wyoming. The final consolidation of the 

continental United States would not be completed until 1912. 

The country's population of 50 million was 

mostly on the land-7 5 percent of the populace 

was rural. The decade of the 1880's saw the 

dawning of our urban, industrialized society. By 

1890, the rural population was down to 63 percent of the total (in 1970, the figure was 26.5 

percent). Many of the people arriving in the 

burgeoning cities were immigrants who came 

in increasing numbers from every part of the 

world. 

The general mood of the country was shifting 

gradually away from the Civil War mentality 

and toward a new sense of Union. The writer 

Robert Penn Warren claimed that, before the 

Civil War, ''The Union sometimes seemed to 

exist as an idea, and ideal, rather than as fact." 

Americans in the 1880's embraced the fact that 

theirs was indeed a united nation. 

South Carolina, as well as other Southern 

States, was rebounding from the devastation of 

the Civil War. Because every sphere of South1Department of History, Virginia Polytechnic Institute and 

State University. 2Seismological Observatory, Virginia Polytechnic Institute 

and State University. 

v 

ern life had been affected, recovery encompassed a broad spectrum of human activities. 

Economically, the citizens struggled to get back 

on their feet and to become a productive society again. 

The northwestern corner of South Carolina is 

occupied by the Blue Ridge Mountains. The 

land drops in stages to the southeas\ across the 

Piedmont Plateau to the Coastal Plain. In the 

1880's, South Carolinians recognized a northeasterly trending line that separated the Blue 

Ridge from the other two provinces and bisected their State. The two regions formed by 

this division commonly were called the "Up 

Country" and the "Low Country." 

Because the Up Country and the Low Country differed in customs, economy, and history, a 

strong strain of sectionalism existed (and some 

would say still exists) in South Carolina. The 

Low Country was dominated by the cultural 

and economic influence of Charleston, a city 

that had been long established by tl'~ 1880's. 

The Up Country had no one dominant center, 

and it was decidedly rural, even still partially 

unsettled in the 1880's. 

Charleston is the heart of the Carolina Low 

Country. In an 1886 editorial exalting the 

virtues of Charleston, the local paper, the News 

and Courier stated, "Nature has dor~ every 

thing she possibly could for Charles~on. " In 

many respects that was absolutely c'Jrrect. Situated on a large bay formed by the c'Jnfluence 

of the Ashley and Cooper Rivers, the natural 

setting of Charleston is beautiful and inviting. 

It seems the earliest settlers of Char ~s Town 

(named after Charles II of England) in 1680 responded to this beauty because Charles Town 

developed as a charming city with C

1

istinguished buildings, wide boulevards, and grace-
ful gardens. It expanded steadily and became a 

busy port and trading center; it was the regular 

stopover for ships sailing between the Caribbean and Great Britain. 

By 1720, Charleston was a thriving city with 

a population of many thousands. Along with a 

reputation for beauty, Charleston gained a reputation as a free and open society. However, it 

is a marvel that the Charlestonian's spirit of optimism withstood all the natural and manmade 

traumas that were experienced during their 

city's long history. In precolonial and colonial 

times, the Charleston coast was a prime target 

for ruthless pirates, including the blood-thirsty 

Blackbeard. During the American Revolution, 

Charleston was under a state of siege culminating in occupation, in 1783, by the British Army. 

Subsequently, Charleston and the surrounding 

countryside suffered great damage at the hands 

of looting British soldiers. After the Revolution, 

the city was incorporated (1783) and changed 

its name from Charles Town to Charleston, 

thereby eliminating any association with Great 

Britain. 

The damage of the colonial and Revolutionary periods was merely a prelude for what befell Charleston during the Civil War and Reconstruction. Charleston had been a hotbed of 

secessionist fervor, and when, on April 12, 

1861, the first shots of the Civil War arched 

over her harbor at Fort Sumter, a quick victory 

for the Confederacy was anticipated. Although 

protected by Confederate troops, Charleston 

was under constant bombardment by Union 

forces from April 1863 to February 1865. On 

February 18, 1865, Charleston was occupied by 

Union troops following in the wake of retreating Confederate soldiers. Less than 2 months 

later, the Confederacy surrendered. 

In September 1865, a northern reporter wrote 

that Charleston was "a city of ruins, of desolation, of vacant houses, of widowed women, of 

rotting wharves, of deserted warehouses, of 

acres of pitiful and voiceless barrenness." Obviously, the more true because Charleston was 

administered by sometimes ill-advised and selfserving Reconstruction governments. Reconstruction mayors and city councilmen invested 

in financial schemes, often involving railroads, 

that were destined for failure and not useful in 

restoring solvency to Charleston. Despite this, 

Charleston did make small strides toward recovery. South Carolina was readmitted to the 

Union on June 25, 1868, and Federal troops 

were withdrawn in 1876. 

So, in the 1880's, Charleston was a city on 

the mend, but a city that still faced great challenges. Civil War damage remained in evidence; civic leaders had to juggle the tasks of 

repairing this damage and the modernizing of 

Charleston at the same time. The Reconstruction governments left Charleston with a debt in 

excess of $4.7 million. Fortunately, during most 

of the 1880's, Charleston had an able: and energetic businessman for mayor, William A. 

Courtenay. Under Courtenay's admir.istration, 

the debt was reduced slowly while public improvements were undertaken. To accomplish 

this, Courtenay had to maintain a fairly high 

level of local taxation, a measure abtorrent to 

his conservative nature. Neverthelesfr citizens 

were pleased with the many improvements. 

Charleston's port remained relative:ly busy; 

the major exports were cotton, phosphate rock, 

lumber, rice, naval stores (rosins and turpentine), fruits, and vegetables. Manufacturing of 

lumber products and various types of machinery became important local enterprises. Socially 

and culturally, Charleston had alway~ been a 

city with much to offer. From colonial times onward, it had been a center for the pe:forming 

arts, and, during the 1880's, interest in such 

performances was running high. A survey of 

the 1885-1886 theater season shows that 

Charleston audiences were richly and variously 

entertained. 

Clearly, Charleston in the 1880's was a city 

undergoing social and cultural renewal. The 

basis of its aesthetic reputation was t~e architecture of the city. Residents were jurtly proud 

of their many beautiful and unique b1.tildings. 

Thus, Charleston was to become a center for 

the conscientious preservation of histr1rical 

buildings long before it was a fashior <ible idea 

in other parts of the United States. Tl· ~ Society 

for the Preservation of Old Dwellings was a 

very active organization that encoura~ed the 

city government and private citizens to promote 

Charleston's cultural heritage by prererving 

and improving old structures. 

In 1883, Charleston celebrated the centennial 

of its incorporation. In honor of that or:casion, a 

local writer, Arthur Mazyck, wrote a book 

about Charleston in which he include:d short 

descriptive essays about some of the city's 

buildings of distinction. He included sketches 

of City Hall with its white marble double staircases; the Court House, considered to be one of 

the handsomest brick buildings in Charleston; 

and the Hibernian Hall, built in the Greek revi 
vival style and fronted by massive fluted 

columns. Mazyck also described two of the oldest churches in Charleston, St. Michael's and 

St. Philip's, in detail because they were held in 

great admiration by the citizenry. 

Summer 1886 was typical; it was sultry, and 

many citizens sought relief from the summer 

sun in other parts of the State or country. The 

Charleston baseball team, although supplied 

with many loyal fans, was hovering at the bottom in the league standings. Charlestonians 

were enjoying cruises on the bay, eating ice 

cream at one of the many local parlours, going 

to the beach, or any other quiet activity to keep 

as cool as possible. The News and Courier 

published a column of local interest called 

"Odds and Ends. II For August 31, 1886, the 

column recorded the following items: 

1. "Yesterday, the Union Cotton Press was 

started for the first time this season-a 

small lot of raw cotton was compacted and 

baled for shipment to New York. II 

vii 

2. jj Many Charlestonians are due back in the 

city tonight after completing an extended 

mountain excursion. II 

3. "At the present rate of improvement, the 

new stores on King Street will present a 

solid plate-glass front from Market to Calhoun Streets by next Christmas. II 

4. "The repairs to St. Michael's Church steeple 

[damaged by a hurricane in 1f')5) have 

been finished, and the scaffolding has 

been taken down. The workmen are now 

engaged on the interior of the building. II 

Given the gift of prophecy, the columnist might 

have added: 

5. The rocks of the upper crust in the 

Charleston area are strained to their 

breaking point. They will rupture this 

evening just before 10:00 p.m., and the release of their pentup energy will cause 

death, injury, and terrible dest-uction 

throughout the city and State. 

CONTENTS 

Foreword iii 

Preface 

Charleston and the Nation in the 1880's v 

By Nancy Buxton and G. A. Bollinger 

Chapter 1 

Introduction 1 

Chapter 2 

Properties of the earthquake source 5 

Chapter 3 

The epicentral area immediately following the 9:50 

p.m. origin time 15 

Chapter 4 

Origin time + 30 seconds-50 miles distant 23 

Chapter 5 

Origin time + 45 seconds-90 miles distant 25 

Chapter 6 

Origin time+ 1 minute-120 miles distant 28 

Figures 

1. Isoseismals of the Charleston earthquake 7 

2. Isoseismals within the epicentral tracts 8 

3. Isoseismal map of the Eastern United States contoured to show the broad regional pattern of 

the reported intensities for the 1886 

Charleston earthquake 10 

4. Isoseismal map of the Eastern United States contoured to show the more localized variation 

in the reported intensities for the 1886 

Charleston earthquake 11 

5. Epicentral area map for the 1886 Charleston, 

South Carolina, earthquake 12 

6. Hypocenters near Charleston, 1973-79 13 

7. Damage on Hayne Street, Charleston 15 

8. Damage to the police station, Charleston 16 

9. Damage to St. Philip's Anglican Church, 

Charleston 17 

10. Wrecked wood-frame house, Summerville 19 

11. Derailed train at the 9-mile point 20 

12. Soil fissure on the bank of the Ashley River 21 

ix 

Chapter 7 

Origin time + 2 minutes-240 miles cistant 31 

Chapter 8 

Origin time + 3 minutes-360 miles cistant 34 

Chapter 9 

Origin time+ 4 minutes-480 miles distant 37 

Chapter 10 

Origin time + 5 minutes-600 miles distant 39 

Chapter 11 

Origin time + 6 to 8 minutes-720 miles distant 42 

Chapter 12 

Concluding remarks 44 

Acknowledgments 46 

References cited 47 

Appendix 

The size of earthquakes-Magnitude and in tensity 49 

13. Sand craterlets at Ten-Mile Hill 22 

14. Cities and towns at an epicentral distance of approximately 60 miles 23 

15. Cities and towns at an epicentral distance of approximately 90 miles 25 

16. Cities and towns at an epicentral distance of approximately 120 miles 29 

17. Cities and towns at an epicentral distance of approximately 240 miles 32 

18. Cities and towns at an epicentral distance of approximately 360 miles 35 

19. Cities and towns at an epicentral distance of approximately 480 miles 38 

20. Cities and towns at an epicentral distance of approximately 600 miles 40 

21. Cities and towns at an epicentral distance of approximately 720 miles 43 

A-1. Relation between body-wave magnitude 

and surface-wave magnitude for earthquakes 

in the Eastern United States 5(' 

The 1886 Charleston, South Carolina, 

Earthquake-A 1986 Perspective 

By Otto W. Nuttli1, G. A. Bollinger2, and Robert B. Herrmann1 

CHAPTER 1 

Introduction 

August 31, 1886, began as an ordinary summer day in Charleston, South Carolina. It was 

hot, humid, unusually sultry, and quiet in the 

late afternoon from 5 p.m. until sunset. No 

trace of the breeze that usually accompanied 

the rising tide was felt. Suddenly, at 9:50p.m., 

the quiet was shattered by a roaring noise, a 

thumping and beating of the earth underneath 

buildings, a collapsing of buildings, the 

screams of anguish and fear of the residents, 

and then, suddenly, an abrupt return to quiet, 

all within a time span of only about 1 minute. 

South Carolina had just experienced the largest 

earthquake in historic time in the United States 

east of the Appalachian Mountains. 

Much has been written of the tragedy that 

accompanied this earthquake and its many aftershocks. Furthermore, numerous scientific 

studies have been carried out to better understand its cause and effects. Some began immediately after the earthquake, but the most extensive and expensive are taking place right 

now. Questions to which answers are being 

sought include the following: Why did such a 

disastrous earthquake happen near Charleston? 

have such earthquakes happened there before, 

and will they happen there again? is there 

something special about the geology near 

Charleston, or can similar earthquakes be expected to occur in other places? how severe 

was the earth motion, and how extensive was 

1Department of Earth and Atmospheric Sciences, Saint 

Louis University. 2U.S. Geological Survey and Department of Geological 

Sciences, Virginia Polytechnic Institute and State University. 

1 

the area involved in the fault rupt·ue process? 

and how can injury, loss of life, and economic 

impact be reduced in the event of future 

earthquakes? 

Although this book cannot hope to answer all 

these questions, and others that might be 

posed, it can address some of them and provide 

a rational explanation of many of the phenomena that were associated with the disastrous 

earthquake and its aftershocks. V\7 e shall do this 

by putting forth a physical picture or model of 

what happened throughout the CC'lintry at the 

time of the earthquake. 

Before beginning this rather formidable task, 

we might anticipate some questio:qs that the 

readers likely have. Could the 1886 earthquake 

have been predicted? and what about future 

earthquakes? The easiest, and lecst satisfying, 

answers to these questions are simple "no's." 

However, our goals, as scientists and engineers, 

must include prediction or, at least, the identification of areas of greatest hazard. Along with 

this, the public and the officials concerned with 

public safety and welfare expect and require 

some estimation of the amount ar1 degree of 

damage that would result. Additionally, they 

need to know the probability or likelihood of a 

severe earthquake occurring in tl' c.ir area in a 

certain time interval. 

No one can claim that the August 31, 1886, 

earthquake was predicted. However, from 

hindsight, we can ask if some clues or hints 

that such a disaster was impending were noticeable. The first thing that comes to mind is 

the occurrence of foreshocks, which are small 

earthquakes that precede by hours, days, 
months, and, perhaps, even a few years the 

main shock or large disastrous earthquake. 

In his accounts of the earthquake at 

Charleston, Dr. G. E. Manigault, a physician, 

mentioned that the area was subjected to several little tremors in June and even earlier 

(Dutton, 1889). After giving two specific examples, he noted: 

"There were several other slight disturbances noticed by different people, which have become interesting since, in consequence of what occurred 

afterwards. They are all well authenticated, and 

show that the more serious shocks were preceded 

for several weeks by smaller preliminary ones, 

which were not distinctly identified at the time." 

Some of these tremors may not have been foreshocks but could have been due to acoustic effects caused by gunfire from naval vessels. 

However, Manigault noted that the tremors 

were more distinct at the village of Summerville, about 20 miles away, than at 

Charleston, and even more distinct at ~~TenMile Hill." Both points were closer to the epicenter of the main shock and were farther 

away from the ocean. Manigault continued 

(Dutton, 1889, p. 231): 

"The first decided shock was felt at Summerville 

on the morning of August 27, but it was not noticed at Charleston. The next day, the 28th, another shock was felt at Summerville at 4:45 a.m., 

and it was distinctly felt at Charleston at the same 

hour, and during the day there were several other 

shocks at Summerville. The movement at 

Charleston consisted of a slight rocking of houses 

and rattling of windows." 

In retrospect, it appears reasonable to conclude that the August 31, 1886, main shock was 

indeed preceded by a number of foreshocks. 

Even though felt earthquakes occurred in the 

Charleston area in the 100 years preceding 

1886 and in the 100 years following it, nowhere 

in that 200 years do we have a comparable 

number felt at Summerville (or any other 

neighboring town) in such a short interval of 

time, except, of course, in the first few years 

following the main shock. It would be most interesting and useful to have an accurate count 

of the microearthquakes (those too small to be 

noticed by people and only capable of being 

detected by sensitive nearby seismographs) 

that preceded the main shock to see exactly 

how the microearthquake activity correlated 

with the felt effects in the months of June 

through August 1886. 

Even at our present state of knowledge, 

merely on the basis of an increase in the level 

2 

of microearthquake activity and on the more 

frequent occurrence of small, perceptl:lle 

tremors, we would not be justified in predicting 

that a large earthquake would follow. Numerous examples of swarms of small- ancl. 

moderate-sized earthquakes that continue for 

days to a few years that are not follovved by a 

big earthquake are found in other parts of the 

world, including the United States. Tl'~refore, 

we can conclude that the occurrence of the 

foreshocks in 1886 near Charleston was, by itself, insufficient reason for a predictio:'l that 

such a large earthquake would follow. Furthermore, the foreshocks gave no indication as to 

the date, the size, or the exact location of the 

large earthquake to follow. 

When a major earthquake occurs, immediate 

attention is given to the people affected-the 

injured, the dead, the homeless, and the frightened and, unfortunately, also to those, such as 

looters, who seek to gain advantage from the 

misfortune of others. Therefore, the first concern is always to bring life back quickly to as 

normal a state as possible. Depending upon the 

severity of the aftershocks, prompt resumptiom 

of usual activities often can range fror- difficult 

to near impossible. It is made easier when contingency plans for such emergencies c.re available and when governmental and private disaster relief agencies are prepared to respond 

quickly. Naturally, no such plans existed for the 

Charleston area in 1886, but it is instructive to 

see how effectively the citizens resporded to 

this completely unexpected disaster, a: described by Carl McKinley, a reporter for the 

Charleston News and Courier (Dutton. 1889, 

p. 212-225). The immediate reaction by the 

Charleston populace was one of terror and 

panic. People rushed out of buildings to open 

spaces and away from the falling debris. 

McKinley described how a crowd rushed by a 

woman lying prone on the pavement, not pausing to see if she were dead or alive. Fires, 

which were blazing all around, were ignored 

by the people as they gathered in crovrds. Although they fled their homes with no regard to 

precious items contained in them, they did give 

thought to invalids, who were placed on mattresses in the roadways. The dead and 

wounded were moved to parks and public 

places where the wounded were attended to by 

physicians and nurses. 

Almost everyone camped out the nirht of 

August 31, during which aftershocks a1ded to 

their terror in the darkness and of the un-
known. By morning, they began the work of 

clearing the rubble, of which 10,000 cartloads 

were said to have been removed in 1 week. In 

spite of continuing aftershocks, people sorted 

out bricks from the debris and began the job of 

rebuilding within 2 days. By that time, the 

stores and shops that had not been destroyed 

were reopened for business. The merchants 

carried out relief work, as did committees set 

up by the churches. Sailors from ships at anchor joined with private citizens to clear debris 

and to provide food, shelter, and emotional 

support to the needy. 

Today, a large earthquake always attracts the 

attention of the news media. Even a minor 

earthquake that does no harm but awakens the 

sensibilities of the people can be the cause of 

thousands of telephone calls to the police, 

newspapers, radio, and television stations and 

to universities and governmental institutions 

that operate seismograph stations. The seismologists and other earth scientists then are faced 

with a number of competing tasks. They must 

locate the earthquake or earthquakes; determine their magnitudes; provide an explanation 

of what has occurred and what might be expected; provide general advice on proper behavior during earthquakes; install portable instruments to locate and measure the strong 

ground motion of the aftershocks; and observe, 

assess, and document the damage to structures 

before it is modified by clearing of rubble and 

restoration. Obviously, no one person is capable of performing all these tasks. Fortunately, 

some of the important information about the 

physics of the earth rupture process can be deduced from seismograph records, called seismograms, made at distant points, at places 

where no sense of urgency is present. However, other critical measurements and observations must be made in the affected area, and 

the sooner the better. 

In the case of the Charleston earthquake, 

communication with the outside world was cut 

off because the telegraph lines were downed 

and the railroads were out of operation due to 

damaged track. Rumors and exaggerated 

claims of destruction were prevalent, adding to 

the anxiety of those who were separated from 

their family members. Thousands fled the area 

in the days following the earthquake. Nevertheless, as noted by McKinley (Dutton, 1889, 

p. 220): 

"It must not be supposed, however, that all the citizens were so demoralized. The authorities and 

3 

subordinates in every department of the local government remained at their posts and dischuged 

their difficult and added duties with a zecl and 

ability befitting the occasion, and that took no note 

of personal risk or private interest. Aid all d relief 

were promptly extended to all who were in need. 

The public offices and institutions were kept open 

or removed to convenient places; order was preserved; private citizens devoted their time, energies and money without stint to the service of the 

community; and so efficiently was the work of organized succor performed, both then and later, 

that none, however, poor and humble, wl·') made 

his wants known or could be discovered by vigilant inquiry and search, suffered for food or for 

such shelter as could be provided." 

Attention to the scientific and engineering 

study of the earthquake and its effects was not 

only immediate, but also thorough. On September 1, the Director of the U.S. Geological Survey sent W. J. McGee to Charleston to investigate the field evidence. He was followed 1 day 

later by Professor T. C. Mendenhall of the U.S. 

Signal Service. Earle Sloan, a native of 

Charleston, joined McGee in a detailec1

. examination of the effects of the earthquake in the 

epicentral region and in Charleston. Capt. 

Clarence E. Dutton of the U.S. Ordnance Corps 

began his studies in October, after traveling 

across the country from Oregon. His report 

(Dutton, 1889), which incorporated the studies 

of McGee, Mendenhall, Sloan, and oth~rs, remains the classic document on the earthquake. 

The fault movement that was the cause of the 

1886 South Carolina earthquake did not rupture the Earth's surface, but rather war confined to its interior. Therefore, an important 

piece of direct field evidence, the direction of 

the trend (termed by geologists the "st:i.ke") of 

the fault surface was not provided for this 

earthquake nor was the direction of movement 

on the fault; that is, vertical, horizontal, or some 

combination. However, observed ground effects 

included sand craters and landsliding along 

river banks, consequences of the shaking of the 

ground by the earthquake waves and of the 

properties of the soil that were favorat 1e for the 

occurrence of such phenomena. Also, disturbance of manmade structures, especially railroad 

tracks, was notable in the epicentral region. 

These and related types of information are useful in assessing the strength and inferring the 

direction of fault movement of the earthquake. 

By correlation with similar data from n1odern 

earthquakes for which direct evidence of the 

fault movement is available, we can make 
some reasonable estimates of the strength of 

the earthquake, including the area of fault rupture and the average amount of slip movement 

on it. Such studies (Nuttli, 1983) imply that the 

4 

fault rupture area of the 1886 earthquake was 

approximately 230 square miles and that the 

average slip or movement over the fault plane 

of the area was about 80 inches. 
CHAPTER 2 

Properties of the Earthquake Source 

The first questions that are asked about any 

large earthquake are where did it happen? and 

how big was it? Although they usually are 

asked out of curiosity, they are obviously important for scientific and engineering reasons. 

Scientists wish to know the location so that 

they can relate the earthquake to a particular 

geologic fault. The size of the earthquake, in 

turn, is related to the amount of slip or displacement along the fault and to the area of its 

rupture surface. Engineers need to know the 

strength of the earthquake to assess the effects 

of ground shaking on structures. A knowledge 

of the strength and the location is needed to 

design and construct new buildings that will 

survive future earthquakes. 

Seismographs are instruments that provide 

the basic information necessary to determine 

the location and beginning time of an earthquake (called hypocentral parameters) and its 

size (called magnitude). Specifically, a seismograph is an instrument attached to the Earth 

that gives a permanent recording of the ground 

motion as a function of time, more or less like a 

continuously running movie. The ground movements from earthquakes are divided into three 

components-vertical and two horizontals, usually north to south and east to west-by using 

three separate instruments. Each of the three 

will respond only to, and thereby measure, the 

ground motion in one of the three directions. 

The size range of ground movements to be 

measured by seismographs is very large. Depending upon the strength of the earthquake 

and the distance of the seismograph from the 

earthquake, the measurable ground displacement can vary from about 40 billionths of an 

inch to about 40 inches. Therefore, different 

kinds of seismographs are needed to measure 

the weak and the strong motion. The former 

kind, which are called observatory seismographs, may magnify the ground movement a 

5 

million or more times. The latter, whic':l are 

called strong-motion seismographs, ac~ually 

may demagnify the ground motion. Seismographs can be made to record on varic1s 

media, as simple as an ink pen tracing a line 

on a piece of paper or as sophisticated as digital recording on tapes or discs that serTe as direct input to modern computers. 

When an earthquake occurs, different vibrational waves spread out from the point at which 

the rupture on the fault occurs. This point is 

called the hypocenter, or the earthquake focus. 

The point directly above the hypocenter on the 

Earth's surface is called the epicenter. The 

waves travel outward in all directions with 

speeds that depend on the physical properties 

of the rock. These speeds are known to seismologists from specially designed me~surements and studies. Therefore, by measuring the 

time at which the first wave from the earthquake arrives at three or more seismo::uaph 

stations and by knowing the wave's speed of 

travel, the seismologist can determine by triangulation the location of the hypocenter (its latitude, longitude, and depth) and the earthquake 

origin time (the time at which the rupturing 

began). 

"Magnitude" was the name given 1: 'l Professor C. F. Richter (1935) to the number that expresses the earthquake's strength. He borrowed 

the term from astronomy, where the n1agnitude 

scale measures the brightness of stars. Anumber of different magnitude scales, sue:"! as local 

magnitude (Md, body-wave magnituc.e (mb), 

surface-wave magnitude (Ms), and seismic moment (M0 ), are in use by seismologistr .. The 

local and body-wave magnitudes mea sure the 

strength of the short-period (approximately 

1-second) waves generated by the earthquake, 

the surface-wave magnitude measure; the 

strength of the intermediate-period (approximately 20-second) waves, and the seismic mo-
ment measures the strength of the very long 

period (greater than 100 -second) waves. For the 

same earthquake, the values of the magnitudes 

as measured on the different scales generally 

will be different. Again using the astronomical 

analogy, the infrared radiation of a star is usually different from the ultraviolet, and the ratio 

of the infrared to ultraviolet will be different for 

individual stars. Earthquakes also have individual source characteristics, although they often 

are similar for events in the same geographic 

region. A more complete discussion of earthquake magnitude scales is given in the Appendix. 

The first seismograph in the United States 

was installed in 1887 at the Mount Hamilton 

Observatory of the University of California at 

Berkeley. Although a few seismographs may 

have been operating in Europe and Japan on 

August 31, 1886, they would have been too insensitive (magnification too low) to have given 

useful recordings of the South Carolina earthquake. Therefore, we have to rely completely 

on the descriptive accounts of the effects of the 

earthquake to estimate its hypocentral parameters and size. Obviously, we cannot do nearly 

as much or as well as if data from modern seismographs were available. 

Intensity scales are used to assess the effects 

of an earthquake on buildings, land, and people and thus represent another type of measure 

of earthquake "size." The highest value of intensity is observed at or near the epicenter. In 

general, intensity decreases as epicentral distance increases. In 1886, the Rossi-Forel scale, 

which was developed in 1883 to measure intensity in Europe, was in general use in the United 

States (it was superseded by the Modified Mercalli Intensity (MM) Scale in 1933; comparison 

of the scales is given in the Appendix). Dutton 

(1889) prepared two intensity, or isoseismal, 

maps of the 1886 earthquake. (An isoseism is a 

line on a map separating regions that experience different levels of intensity.) His generalized map is shown in figure 1 r and his map of 

the epicentral area is shown in figure 2. 

In preparing figure 1, Dutton (1889) relied, 

for the most part, on newspaper accounts of the 

earthquake, especially at the larger distances. 

He used the Rossi-Forel Scale after experimenting with others that were in vogue at the time. 

It is well to consider some of his words of caution with regard to the reported accounts (Dutton, 1889, p. 349): 

6 

" ... the American newspaper reporters frequently 

consider it for the interest of the journal.,. they 

serve to tincture their accounts with twc qualities: 

first, the sensational; second, the funny. This habit 

may or may not promote the interests of journalism. It does not help the scientific inves"'"igation of 

the earthquake. There are certainly many gratifying exceptions to the general rule. Some of the accounts, especially those given by the pr1~ss associations, were written with calmness, sinc~rity, and 

dignity, and bear internal evidence of sincere efforts to state whatever facts were noted with exactitude and candor. The greatest defect of such reports is a negative one: they seldom state that the 

earthquake was not felt where it might have been 

expected to be sensible. Confining therr.selves to 

statements of the most striking results and silent 

about everything else, they are apt to le"'.ve the 

impression that these emphatic manifestations are 

typical or representative while in reality they are 

exceptional, and unless caution is exercised by the 

investigator are also misleading. It is interesting 

and quite as important to know what the earthquake failed to do as to know what it di':l." 

Dutton's words of caution are still worth 

heeding. Sometimes, however, certain newspaper editors present a countervailing attitude. 

For various reasons, they downplay the severity 

of the motion. One reason might be th<it they 

wish to present a strong, calm image, and they 

do not want to admit that they or their fellow 

citizens were frightened by or even a·ware of 

the ground shaking. Another reason, which is 

rather common, is to ignore earthquakes because mention of them might make their 

community appear to be a less desirable place 

in which to live or to locate new indus~rial 

developments. 

A remarkable feature of Dutton's iso~~ismal 

map (fig. 1) is the large area over which the 

earthquake was perceptible to people-almost 

all the United States east of the Mississippi 

River. The perceptible, or felt, area wa: approximately 2 million square miles which can be 

compared to 375,000 square miles for the 1906 

San Francisco earthquake. However, [ ·1tton 

(1889, p. 346) noted that the New Mad·id 

earthquakes of winter 1811-12 were rruch 

larger, being " ... a convulsion vastly exceeding 

that of Charleston." He arrived at this conclusion by making use of the reciprocity r'inciple; 

that is, by comparing the intensity of tl·~ New 

Madrid earthquake at Charleston with the intensity of the Charleston earthquake at New 

Madrid. The distance between the epicenters of 

the two earthquakes was about 600 miles. The 
ISOSEISMAL5 OF THE 

CHARLESTON .EAR:l'HQUAKE 

ROSSI·FORE:L. SCALE 

Scale of:Mik•. 

Figure 1. Isoseismals of the Charleston earthquake. (From Dutton, 1889.) 

7 
1 

1' 

0 

1'/te two ,,,;rmtm7 tmds are lnificatdl{f;-aroilmty 

tsoscismaLau11'S: tlu•ltem·:rlillr br.irw lltr. tJtdcJ.:. 

Figure 2. Isoseismals within the epicentral tracts. (From Dutton, 1889.) 

8 
1886 earthquake was felt at New Madrid " ... 

only as a very feeble tremor, noticed indeed by 

a number of persons, but exciting no comments 

at the time because such tremors are felt there 

rather frequently." The 1811 earthquake, on 

the other hand, was felt strongly in Charleston, 

as " ... violent at least as that of the Charleston 

earthquake in Atlanta, Asheville, Raleigh, and 

Wilmington. The accounts given by localities 

situated about 200 miles from Charleston approximate very closely the indicated intensity of 

the New Madrid earthquake in Charleston." By 

examining figure 1, it follows that Dutton 

placed the Rossi-Forel intensity of the 1811 

New Madrid earthquake in Charleston at VII 

and of the Charleston earthquake in New 

Madrid at IV. 

The purpose of figure 2, as prepared by Dutton, was to show evidence of two epicenters, 

one to the northwest of Charleston and the 

other almost due west of Charleston. An alter- ,. 

nate interpretation, to be discussed later, is that 

the II epicenters" of Dutton represent the points 

of initiation and termination of the fault 

rupture. 

Bollinger (1977) reinterpreted Dutton's basic 

intensity data using the modern Modified Mercalli Intensity Scale. His generalized map for 

the Eastern United States is shown in figure 3. 

Figure 2 (by Dutton) and figure 3 (by Bollinger) 

are very similar, although the latter shows 

somewhat more detail. However, both maps indicate almost identical areas of perceptibility 

and identical areas of structural damage. 

Bollinger (1977) also prepared an isoseismal 

map of the Charleston earthquake for the Eastern United States that was contoured to show 

the more localized variations in reported intensities for the 1886 earthquake (fig. 4). It shows 

how local surficial conditions [soil and (or) rock, 

as well as ground water levels] and topography 

can cause departures from average intensity 

values by as much as plus or minus two intensity units. 

Figure 5 is a reproduction of Bollinger's epicentral area map for the 1886 earthquake, with 

the isoseismal curve enclosing intensities corresponding to X on the Modified Mercalli Intensity Scale. The town of Middleton Place is near 

the center of the isoseism. Recent studies by 

Dewey (1983). who relocated the South Carolina earthquakes that occurred from 1945 

through 1974 by reevaluating the seismographic data, and by Tarr and Rhea (1983), 

who used a microearthquake network of stations to locate the epicenters of earthquakes 

near Charleston that occurred from March 1973 

through December 1979, show that the area 

outlined by the solid-line curve in figure 5 is 

also the region of present-day earthquake activity, as shown in figure 6 (Tarr and Rhea, 

1983). Assuming the epicenter of the 1886 

earthquake was within this area, its ericentral 

coordinates would be 33.0 ± 0.1° N, 

80.2 ± 0.1° w. 

Although numerous examples of sand craters 

and other soil disturbances in the epicentral region of the 1886 earthquake were fourd, no evidence of fault rupture was observed at the 

Earth's surface. Surficial faulting, whic~ is common for earthquakes in California and the 

Western United States, has never been observed for historic earthquakes in the Eastern 

or Central United States. 1 This suggests that 

the depth of the eastern earthquakes is large 

enough so that the rupture is confined to the 

rock mass beneath the surface. Nuttli and Herrmann (1984) gave a formula for the minimum 

focal depth, as a function of body-wave magnitude, when such conditions prevail. Fo:r the 

1886 earthquake, this minimum focal c~epth is 

found to be approximately 12 miles. Tc.rr and 

Rhea (1983) indicated that the depths of the 

present-day microearthquakes are, for the most 

part, between 3 and 9 miles, as can be seen in 

figure 6, which is taken from their worlr. 

9 

Bollinger (1977) used his generalized intensity map and two different relations be~een 

Modified Mercalli intensity and grounc1

. particle 

velocity to estimate the body-wave magnitude 

of the 1886 earthquake. By employing a relation, developed for the Central United States, 

between intensity as described by the Modified 

Mercalli Intensity Scale and ground velocity, he 

obtained a body-wave magnitude estimate of 

6.8, whereas a relation obtained from Western 

United States data gave a body-wave ragnitude estimate of 7.1. Nuttli and others (1979), 

by means of a somewhat similar approach, estimated the body-wave magnitude to be 6.6. 

However, by using correlations of the orea enclosing MM IV effects with the body-wave 

1 A possible exception is the Meers fault of so·1thwestem 

Oklahoma, which shows repeated offset in the late Quaternary sediments, the most recent event occurrin~ within the 

last few hundred to a few thousand years (Tilford and Huffman, 1985). Total horizontal offset exceeds 66 feet (Ramelli 

and Slemmons, 1985). The area was settled in 1860, and, since 

that time, no earthquakes have been felt, and no evidence of 

an earthquake of body-wave magnitude 4 or larger has been 

found (Lawson, 1985). 
45° 

40" 

<-t-

" 

4.J 

u 

0 

--\-

35° 

-\- u 

..... 

I-. 

< 

" 30" 

'-.J 

I-. --\-

+ " 

G U L F 0 F MEXICO 

25° 

0 200 400 MILES 

l I I 

I I I I I I I 

0 200 400 KILOMETERS .J_ 

75 

Figure 3. Isoseismal map of the Eastern United States contoured to show the broad regional pattem of the 

reported intensities for the 1886 Charleston earthquake. Contoured intensity levels aw shown in 

roman numerals. (From Bollinger, 1977.) 

magnitude, they estimated a body-wave magnitude value of 6.9. A weighted average of these 

various body-wave magnitude estimates would 

be about 6. 7. 

Nuttli (1983} presented relations between 

body-wave magnitude and average so,.rrce 

characteristics of earthquakes in easte:o:n North 

America. According to these relations, an earthquake of mb = 6. 7 would have a surface-wave 

magnitude of about 7. 7, a seismic mon1ent of 

10 
40" 

30" 

GULF OF MEXICO 

25° 

200 400 MILES I I I I I I I I I 

200 400 KILOMETERS _l90" 85° 80" 75° 

Figure 4. Isoseismal map of the Eastern United States contoured to show the more localized variation' in 

the reported intensities for the 1886 Charleston earthquake. Contoured intensity levels are -shown 

by arabic numerals. (From Bollinger, 1977.) 

4 x 1026 dyne-centimeters2, a fault rupture 

2Seismologists always express seismic moment in metric, 

rather than British, units. The equivalent relation is 1 dynecentimeter= 2.37 x 10- 6 pound-square feet per square 

second. 

length of approximately 19 miles, a fault rupture width of about 12 miles, and an average 

fault slip of about 7 feet. These values must be 

considered at best as approximations because 

they are based upon no instrumental data, but 

11 
0 

j,·,:,'l' I 0 5 10 

~ 

EXPLANATION 

Railroad track damaged 

• Butlding destroyed 

• Marked horiZontal displacement 

MP + Middleton Place 

10 15 MILES I I 

I 

15 KILOMETERS 

0 Craterlet area 

0 Ch1mney destroyed 

Figure 5. Epicentral area map for the 1886 

Charleston, South Carolina, earthquake. 

Dashed contour encloses the area where 

intensity X effects were observed. Rivers 

flowing past the Charleston peninsula are 

the Ashley, flowing from the northwest, 

and the Cooper, flowing from the north. 

(From Bollinger, 1977.) 

only intensity maps and a number of empirical 

relations. 

If we return to figure 2 and move Dutton's 

northern epicenter to a point about 3 miles to 

the southeast of Summerville (on the basis of 

our earlier discussion), the distance between 

the two "epicenters" of Dutton becomes 

15 miles. Dutton (1889) noted that observers in 

Charleston reported the earthquake disturbances in that city first came from the northwest 

and then from due west. He used this, along 

with the distribution of intensity as shown in 

figure 2, to justify the existence of two separate 

earthquakes. However, in light of our present 

understanding of earthquake rupture nechanics, his observations can be interpreted in a 

somewhat different way. We might infer that 

the rupture of the 1886 main shock began at a 

point a few miles to the southeast of Summerville and progressed to the south, vrhere it 

stopped at a point a few miles to the n0rtheast 

of Adam's Run. The stopping, as well as the 

initiation, of fault rupture gives rise to large 

ground motions, which would explain the existence of two small areas of highest intensity 

separated by a distance of about 20 miles. It is 

interesting to note that the two centers of 

present-day microearthquake activity near 

Charleston, as shown in figure 6, corre;uond to 

the proposed points at which the fault rupture 

began and stopped. From figure 6, the distance 

between these points is close to 19 mila.s. And, 

coincidentally or not, this also is the value of 

the fault rupture length for an earthquake of 

mb = 6.7 in the Eastern United States. Therefore, we might speculate that the strike, or 

trend direction, of the fault associated with the 

1886 earthquake is just slightly east of north 

and that the fault rupture proceeded a distance 

of about 19 miles, travelling from the north to 

the south. 

In recent years, a seismograph network to 

record the more frequently occurring s'llall 

earthquakes (microearthquake networl-) was 

installed by the U.S. Geological Survey in the 

Charleston area. In addition to providing 

information on the epicentral coordinates, 

origin time, focal depth, and magnitude of 

the earthquakes occurring in the regio:'l, the 

microearthquake network also providei data 

that could be used for the determinatic"'l of 

focal mechanisms, namely the orientation of the 

fault planes and directions of the slip nlovement on them. Tarr (1977) studied the mechanism of the November 22, 1974, earthquake, 

which had its epicenter near Middleton Place, a 

depth of about 2 miles, and a body-wave magnitude of 3.8. He obtained two possible solutions. The first corresponded to a fault plane 

striking N. 42° W. and dipping 78° to tl'~ southwest, with the southwestern side displaced up 

relative to the northeastern side. The alternate 

interpretation corresponded to the fault plane 

striking N. 42° W. and dipping gently to the 

southeast, with the northeastern side overriding 

or overthrusting the southwestern side. Tarr 

and others (1981) combined the data o~ 16 

small earthquakes in the Middleton PlaceSummerville area to obtain a composite focal 

12 
81"00' 

33"30' 

~man 

30' 80000' 

{) 

AdamsBH ~ C!:/ 

Run 

or_-,-____.f..._,. __ rL1r_-._ ..... 115""T"""--20"'-I -----~~5 MILES 

I I I I I 

0 5 10 15 20 25 KILOMETERS 

Figure 6. Hypocenters near Charleston, 1973-79. The plotted ellipses are the principal planes (thc~e having 

the largest projected area) of the standard-error ellipsoid. Depth profiles A-A' and B-B' also are 

shown. (From Tarr and Rhea, 1983.) 

mechanism solution that was similar to the first 

of the two alternate solutions for the November 

22, 1974, earthquake, namely a near-vertical 

fault plane striking to the northwest with the 

block to the northeast downthrown relative to 

the southwestern block. 

Talwani (1982) noted that primary-wave velocity abruptly increases at a depth of about 

6 miles beneath the Charleston epicentral area. 

He used that information to relocate th~ earth13 
quakes studied by Tarr and others (1981). 

Then, by combining the spatial distribution of 

earthquake hypocenters with focal mechanism 

studies, he found that the cluster of microearthquakes near Summerville lay at depths of 

about 2 to 5 miles and those at Middleton Place 

at similar depths. The geometry of their distribution in three dimensions indicated a steeply 

dipping, northwest-striking fault plane, consistent with the focal mechanism solution. 

Talwani (1982) also identified another cluster of 

hypocenters, extending from Jedburg to the 

north to just east of Adams Run to the south 

(see fig. 2 for the location of these towns). The 

hypocenters of these earthquakes, which were 

deeper than the hypocenters of those near 

Summerville and Middleton Place, lie below 

5 miles and average 7 miles in depth. The composite focal mechanism solution for these earthquakes indicated horizontal movement on a 

near-vertical plane striking slightly east of 

north, with the western block moving to the 

north relative to the eastern block. He called 

this structure the Woodstock fault and the shallower northwest-striking structure the Ashley 

River fault. 

Talwani (1982) favored movement on the 

Woodstock fault as the likely cause of the main 

shock of 1886. He noted also that Dutton's 

(1889) isoseismal map shows a northwesttrending bulge of isoseismals surrounding Jedburg and Summerville, which might have been 

caused by secondary slipping on the Ashley 

River fault that was induced by the principal 

movement on the Woodstock fault. 

In summary, most of the evidence pr~sented 

in this chapter appears to favor movement on a 

fault trending slightly east of north (the Woodstock fault?) as the cause of the August 31, 

1886, main shock. This includes the fact that an 

earthquake of its magnitude must have been at 

least 12 miles deep because the Earth's surface 

was not ruptured, that the isoseismals in the 

epicentral region are elongated in the northsouth direction, a fact first noted by Taber 

(1914) and used by him to infer a nortr-south 

striking rupture plane, that the focal mechanism, as well as the three-dimensional spatial 

distribution, of the recent microearthquakes of 

depth greater than 5 miles indicates a nearvertical fault plane striking slightly east of 

north, and that Dutton's two "epicenters," or 

points of highest intensity, are located at the 

places where the starting and stopping points 

of fault rupture might have occurred. 

Although the above-mentioned points support horizontal movement on the Wooc~stock 

fault as the cause of the 1886 main shcck, two 

other models that are suggested by microearthquake focal mechanism solutions also will 

be used for constructing synthetic seisrnograms 

at selected distances and azimuths. They are 

vertical movement on the Ashley River fault 

and overthrust movement (northeast over 

southwest) on a gently dipping plane vrith 

strike of N. 42° W. By constructing synthetic 

seismograms for these three very different 

models of the main shock, the effects c f the 

focal mechanism on the ground motion at various points can be observed. 

14 
CHAPTER 3 

The Epicentral Area Immediately Following the 

9:50 p.m. Origin Time 

Dutton (1889, p. 248) noted that not a single 

building in Charleston escaped some damage 

and that only a very few did not suffer serious 

damage. Damage ranged from the loss of chimney tops and the fall of plaster to total destruction. Although the number of collapsed buildings was not large, hundreds lost substantial 

portions of their walls. These, together with 

other severely damaged structures, as illustrated in figure 7 r had to be torn down because 

they presented a hazard to public safety. 

Every brick and stone building in Charleston 

was cracked. A majority were capable of being 

repaired to the point of being habitable but not 

necessarily pleasing to the eye. Wooden buildings fared better than most brick and stone 

buildings, although some moved off their foundations, many suffered chimney damage, and 

interior damage was similar to that of noncollapsed brick buildings. Dutton (1889, p. 249) 

noted: 

"As a general rule, although not without a considerable number of exceptions, the destruction was 

greater upon made ground than upon the original 

higher land." 

As an example, he pointed out that Market 

Street from Meeting Street to the Cooper River 

was "made ground" (soil and rubble fill of an 

area previously covered by water) that extended over an old marsh through which a 

Figure 7. Damage on Hayne Street, Charleston. (From Dutton, 1889.) 

15 
small stream had passed. Buildings on both 

sides of this section of Market Street, without 

exception, were seriously damaged, with some 

walls thrown into the street and others badly 

cracked. 

Most of the large, massive buildings suffered 

notable damage and required extensive repair. 

These included the Court House, the Post Office, the county records building, the police station (fig. 8), the Hibernian Hall, Charleston 

College, the hospital buildings on Queen 

Street, the Unitarian Church, St. Michael's Anglican Church, and St. Philip's Anglican 

Church (fig. 9). Parapets, cornices, porticos, bay 

windows, and chimneys particularly were vulnerable to the ground shaking. Their fall, together with the collapse of brick and stone 

buildings, was responsible for most of the 

deaths and injuries in the city. 

A detailed study of the earthquake damage 

to the buildings in Charleston was commissioned by the insurance companies doing business there. The report was prepared by a committee of three, including an architect and a 

builder who together did the actual inspection. 

Released on December 11, 1886, it gave the 

state of repair for 6,956 buildings in Charleston. 

Robinson and Talwani (1983) obtained a copy 

of this report, which appears to have been 

largely neglected by earlier workers. Robinson 

and Talwani analyzed the data contained in the 

report with the objective of defining some of 

the major factors that contributed to the observed damage. They reported that the location 

of the building (made versus solid ground) was 

only secondarily important and that the most 

important single factor was the type of material 

used in construction. Of the damaged buildings, 81 percent were made of bricks. Only a 

slightly higher proportion of brick buildings located on made ground (69 percent) were heavily damaged compared to those located on solid 

ground (63 percent). For wood-frame structures, 

only 7 percent of all wood buildings were heavily damaged (compared to 65 percent of all 

brick buildings) and, of those, 96 percent were 

on made ground. The type of ground did seem, 

however, to affect the degree of damage in that 

--~-.. -

""'-~ 

Figure 8. Damage to the police station, Charleston. (From Dutton, 1889.) 

16 
buildings of either material on made ground 

experienced more damage than those on solid 

ground. 

In Charleston, the ground shaking began 

with light tremors and a murmuring sound. 

Both increased in intensity and loudness for an 

interval of 10 to 15 seconds, when the destructive shaking commenced and built up to violent 

oscillations and a roaring sound. A relative lull 

followed, which was succeeded by more heavy 

Figure 9. Damage to St. Philip"s Anglican Church, Charleston. (From Dutton, 1889.) 

17 
shaking, although not as violent as the earlier. 

Estimates of the time of most severe shaking, 

including the lull, ranged from 45 to 55 seconds 

(Dutton, 1889, p. 263}. 

Let us attempt to apply our present-day seismological knowledge to the descriptions of the 

ground motion experienced at Charleston. On 

the basis of the overall damage to the city, with 

relatively few collapsed structures but commonly observed fallen or otherwise badly damaged walls of buildings, effects that correspond 

to IX on the Modified Mercalli Intensity Scale 

(MM} for the city itself seem most descriptive of 

the damage incurred (Bollinger, 1977}. For the 

body-wave magnitude (mb} of 6. 7 assigned to 

the earthquake as described in Chapter 2, MM 

IX to X effects are predicted by the equation 

(Nuttli and others, 1984}, 

I(R) = 0.86 + 1.81mb- 2.30 log10 (R2 + h2) 112 - 0.00085 R, 

for an epicentral distance, R, of 16 miles if the 

depth, h, of the earthquake is taken to be 12 

miles. 

For mb = 6. 7, the predicted maximum ground 

acceleration at Charleston, assuming a wave 

frequency of 5 hertz, is 160 inches per second 

per second (Nuttli and others, 1984}, and the 

predicted maximum ground velocity is 32 

inches per second. These are very large ground 

motions, well capable of causing the type of 

damage observed in the city. Campbell (1984} 

estimated peak ground acceleration and velocity for the near-source region of a mb = 6.6 

earthquake in the Eastern United States. For 

soil and soft rock sites, his median values of 

peak acceleration ranged from 102 to 

142 inches per second per second and of peak 

velocity from 13 to 18 inches per second, depending upon the type of fault motion. Increasing the body-wave magnitude to 6. 7 would 

raise the peak acceleration to the range of 114 

to 160 inches per second per second and the 

peak velocity to the range of 17 to 22 inches 

per second. The differences between Campbell's (1984} estimates and those of Nuttli and 

others (1984} reflect the uncertainty in estimates of strong ground motion, which is of 

about the same size as the scatter in instrumentally observed data points in other regions, 

such as California. Therefore, we can conclude 

that the intensity level and maximum ground 

motions calculated for a mb = 6. 7 earthquake at 

a distance of 16 miles from the epicenter are 

consistent with the type of damage that occurred in Charleston. Next let us turn our attention to the time intervals of the various 

phases of shaking. 

At a distance of 16 miles from the epicenter, 

the primary (P} wave would arrive at about 4 to 

5 seconds after the origin time. The secondary 

(S} wave would arrive 2 to 3 seconds after the 

P wave, much too early to explain the violent 

motion (second phase} described as beginning 

10 to 15 seconds after the onset of the first 

tremors (Dutton, 1889, p. 262}. More likely, the 

severe shaking was caused by slow surface 

waves travelling in the soft sedimentary layer 

at speeds of about 1 mile per second and less. 

The protracted nature of surface-wave trains, 

caused by longer period surface waves travelling at greater speeds than short-period surface 

waves, also would account for the relatively 

long duration of the most violent portion of the 

ground shaking. The fourth phase, following 

the lull (third phase} and commencing about 

40 seconds after the first tremors, could be explained by additional sedimentary surface 

waves orginating at the stopping point of the 

fault rupture, if the fault rupture velocity were 

about 213 to 1 mile per second. These values 

can be given only imprecisely because the observations of the time intervals between the 

various phases of the strong ground shaking in 

Charleston were only estimated. 

Because it was sparsely populated, the area 

immediately surrounding the epicenter received less attention than the city of Charleston 

where MM X effects were experienced 

(Bollinger, 1977}. Figure 10 shows an example 

of a wrecked wood-frame building at Summerville. Railroad tracks were bent, and the 

joints between the rails opened 7 inches at the 

5-mile point (measured northwestwardly from 

Charleston}. At the 9-mile point (Dutton, 1889, 

p. 283}, the lateral displacement of the track 

caused derailment of a train, as shown in figure 11. In the epicentral area, the soil rifted 

near the bank of the Ashley River (fig. 12}. 

Sand craterlets, resulting from the extrusion of 

sand and water by the force of the ground 

shaking, were observed at a number of points. 

An example of one located at Ten-Mile Hill is 

shown in figure 13. 

18 
Figure 10. Wrecked wood-frame house, Summerville. (From Dutton, 1889.) 

19 
20 
Figure 12. Soil fissure on the bank of the Ashley River. (From Dutton, 

1889.) 

21 
22 
CHAPTER 4 

Origin Time + 30 Seconds-60 Miles Distant 

Seismic wave propagation 30 seconds after 

the origin time of the earthquake extended outward to about 60 miles from Charleston 

(fig. 14). Most severely affected at this range 

from the epicenter of the 1886 shock were 

coastal locations in South Carolina, such as Port 

Royal and Beaufort to the southwest and 

Georgetown to the northeast. At Port Royal [the 

effects corresponded to IX on the Modified 

Mercalli Intensity Scale (MM)], the shock was 

described by Dutton (1889, p. 506), quoting the 

United Press, as "very violent." Houses were 

moved on their foundations, chimneys destroyed, and people were thrown to the ground, 

some of whom were described as being in a 

state of frenzy. At Beaufort [Dutton (1889, 

p. 4 77) quoting an Associated Press report] and 

Georgetown [Dutton (1889, p. 502) quoting 

M.S. Iseman, M.D.] (both MM VIII), chimneys 

and chimney tops were thrown down, brick 

~----

/ _, '"\ ___ .-.,. 

/ ' 

""' ~"'-.. 

\ SOUTH ', 

, CAROLINA ""' 

""' 

'\ ~~ // 

/~ 

~ Orangeburg o . N , / 0 60 ., Georgetown , Bamberg mt.es 

'\ 

1 C~arleston \ / ' Beaufort // 

\ (~Royal Ol (~50 100 MILES 

"( I 

Figure 14. Cities and towns at an epicentral distance 

of approximately 60 miles. 

parapets were dislodged, and brick buildings 

"undulated." Residents fled their house' and 

remained in the streets and fields all night; 

many prayed. The Charleston Year Bock (Dutton, 1889, p. 497) described the shock c-t Beaufort as "very severe;" it lasted 30 seconds, 

cracked some large buildings, and caur~d a 

2-foot depression over an area about 60 feet in 

circumference. 

Noncoastallocations, such as Mannir~ to the 

north and Orangeburg and Bamberg to the 

northwest, were shaken strongly (MM VII). The 

towns reported damage to brick houser. brick 

walls, and plaster. The response of the populace in these areas was also one of terror, and 

many people camped in the open air overnight. 

Dutton (1889, p. 321) observed that, within 

approximately 50 miles of the epicente:--, the 

earthquake motion was strong enough to cause 

considerable damage to buildings and to thoroughly terrify the whole population. He further 

noted that, within this belt, the vibrations failed 

to be more or less disastrous because c'lmparatively little was there to destroy. In his words: 

"The country is a part of the great coastal plain of 

Carolina, containing a considerable numl'~r of 

small villages and an agricultural population. 

Buildings of stone or brick are comparatively rare 

outside the large cities, and none of therr. are lofty 

enough to be greatly affected by the curr.ulated 

swing due to repeated impulses. Thus the injuries 

produced were mostly of the minor sort-the overthrow of chimneys and the shaking dowr of plastering. The few brick structures, however, were 

severely cracked, and often left in a dan~erous 

condition, while several instances are given of 

their virtual demolition. The wooden stru ~tures all 

suffered more or less injury by the straining of timbers and shattering of glass and general destruction of plastering. " 

Dutton also noted that, at this distance, the 

undulatory motion of the ground was very violent. He stated that, within 80 miles of the epi23 
center, all accounts indicated the difficulty of 

standing while the earthquake was at its maximum, with people clinging to fences and trees 

for support. The trees themselves swayed as if 

bent by a powerful gale. 

For an epicentral distance of 60 miles, the 

formulas in Nuttli and others (1984} give MM 

VIII, a peak horizontal acceleration of 39 inches 

per second per second, and a peak horizontal 

velocity of 10 inches per second. Dowding 

(1985} presented data on experiments related to 

damage induced by blasting. Major damage, 

defined as cracking of structures, shifting of 

foundations or of bearing walls, occur~ when 

the horizontal ground velocity exceeds 8 inches 

per second. 

In summary, the damage that occurred at 

Beaufort, Georgetown, and Port Royal is consistent with an estimate of 10 inches per second 

for the peak ground velocity at those towns. 

24 
CHAPTERS 

Origin Time + 45 Seconds-90 Miles Distant 

Two major southern cities, Savannah, Georgia, and Columbia, South Carolina, are approximately 90 miles from the epicenter (fig. 15). 

That distance corresponds to a 45-second travel 

time for vibrations from the epicenter. Savannah, to the southwest of Charleston, is on the 

coast and thus can be expected to have Coastal 

Plain ground conditions roughly similar to those 

at Charleston. Columbia, however, is situated 

to the northwest of Charleston and is near the 

boundary of the Coastal Plain and Piedmont 

provinces. The Coastal Plain sediments, which 

are more than 1 mile thick in the Charleston 

area (Ackerman, 1983), thin to a feather edge 

against the crystalline rocks of the Piedmont 

province. Thus, the vertical configuration of the 

GEORGIA 

r.._ 

- ~:ORIDA- ~ f 

SOUTH 

CAROLINA 

CAROLINA 

Charleston 

\? 

Savannah 

~' 

/ 

0 

I 

0 

I 

50 

50 

I 

I 

100 MILES 

I 

100 KILOMETERS 

Figure 15. Cities and towns at an epicentral 

distance of approximately 90 miles. 

Coastal Plain sedimentary rocks is that of a 

wedge thickening towards the coastline. Those 

poorly consolidated sediments overlie a 

hardrock basement similar to that expofP.d in 

the Piedmont to the northwest and, thuf. constitute a soft, wedge-shaped layer overlying a 

rigid sublayer. Such a situation can cause channeling of earthquake vibrations within the 

wedge with resultant amplification at the thin 

edge similar to that of ocean waves sho::tling 

against a beach. Such may have been the case 

in South Carolina; Dutton (1889, p. 325) noted 

the shaking " ... was certainly more vigorous in 

Columbia than in Savannah." 

Dutton (1889) noted this amplification effect 

in general along a substantial portion of the 

Piedmont-Coastal Plain contact. On pages 327 

and 328, he wrote, 

25 

"The most remarkable circumstance, however, 

connected with Columbia is the fact that a considerably greater intensity is indicated for that city 

than for the localities to the southeast of it nearer 

to the centrum. There is, indeed, a belt of country 

along the Piedmont region where the sam~ state of 

affairs prevailed, and this belt coincides with a 

marked change in the geologic formationr. It is 

that belt where the Tertiary-Cretaceous system of 

marls, sandstones, clays and quicksands forming 

the great coastal plain and lower Piedmort region 

terminate and the more ancient metamorphic crystalline rocks appear. In South Carolina an':l in adjoining portions of Georgia and North Carolina the 

unconformable contact of the older and later rocks 

is found, stretching from northeast to southwest. 

Towards the ocean are the later formatiors, while 

to the northwestward lie the older rocks of the 

Southern Appalachian region. A line drawn from 

the earthquake centrum to Columbia would cross 

the line of contact of the two stratigraphic systems 

almost perpendicularly. The earthquake impulses 

leaving the centrum declined in energy tC'wards 

the northwest at a rate which seems to bE: a natural one, so far as can be judged from the accounts 
at hand. But as they approached the line of contact 

of the younger beds with the older, the energy 

seems to have increased for a time as the waves 

sped onward. Thus at Orangeburg, which is 32 

miles nearer the centrum than Columbia, the account given by Prof. R. Means David leaves little 

doubt that the violence of the shocks was notably 

less. Nor was Orangeburg exceptional in this respect when compared with other localities similarly situated with reference to the contact lines of 

the strata. Similar accounts indicating a more moderate energy come from many other places in the 

same county; also from Barnwell, Williston, Statesburgh, Camden Junction, and Sumter. But if we 

proceed northwestward from these places until we 

reach the older metamorphic rocks we find traces 

of increased vigor." 1 

The shock at Savannah was preceded by a 

rumbling noise and northeast to southwest oscillations. That rumbling increased to a loud 

roar, and the oscillations changed to violent 

and quick vibrations that attained a maximum 

level and then diminished as the sounds also 

became fainter. The initial low-level noise and 

longitudinal (the in-line direction from 

Charleston to Savannah) ground motions probably resulted from the primary (P) seismic 

waves, which are compressional in character. 

The subsequent higher level sounds and vibrations then would be, at least initially, due to the 

secondary (S) seismic waves, which exhibit a 

shearing-type motion. The surface waves have 

the largest ground motions and follow the S 

waves in time sequence of arrival at any given 

point. At this distance, the surface waves likely 

were responsible for most of the damage. 

The city surveyor for Savannah reported that 

240 chimneys were more or less damaged (final 

number probably closer to 300) and that 10 

buildings had seriously damaged walls and 

gable ends. However, the damaged buildings 

were either very old or 11Where the work was of 

flimsy character." The newer buildings of the 

city experienced only cracked walls and fallen 

plaster [compare below with similar effects at 

Columbia; Dutton (1889)]. 

The population of Savannah was panic 

stricken. One woman was reported to have 

died from fright; several women fainted and 

1A continuation of Dutton's discussion of this topic is found 

in Chapter 6. 

were injured severely by crowds that rushed 

over them. Two women in different p<lrts of the 

city leaped from second-story windovrs and suffered broken bones but fortunately were not injured fatally. One of those women had a baby 

in her arms, but it escaped unhurt. Workers 

left downtown buildings; entire families spent 

the night in the streets and other opeTJ. places. 

Dutton (1889, p. 327) reported 11 the shocks at 

Columbia, South Carolina, judging from all ac: 

counts were more forcible than at Savannah.·~ 

Apparently, the aforementioned P and S waves, 

as well as the surface waves, II • •• threw the 

whole city into a state of terror" and 11 • •• the 

cracking of brick walls was apparentl~· much 

more common than at Savannah." During the 

largest ground motions, walking was described 

as II • •• extremely difficult and possible only 

with great care and attention to the footsteps." 

Even though a definite difference in the level 

of seismic shaking at Savannah and Columbia 

was apparent, the above reports appe<lr to us to 

fit within the range of effects appropr<:tte for a 

level of VIII on the Modified Mercalli Intensity 

Scale (MM). 

Use of the equations of Nuttli and others 

(1984) gives a calculated MM VIII, a peak horizontal acceleration of 30 inches per S€(:Ond per 

second (assuming 2-hertz waves), and a peak 

horizontal velocity of 7 inches per seo"lnd. 

These numbers place the ground sha1-tng at, or 

just below, the threshold of structural damage, 

which is consistent with the observations at Savannah and Columbia. 

Dutton (1889, p. 322-325) paid particular attention to the lighthouses on the South Carolina coast. He observed (p. 322), 11The short and quick vibrations of individual 

tremors would probably not affect such structures 

more than ordinary buildings, but the lo'lg undulations would be greatly magnified at the tops of 

high towers." 

The 35-foot-high tower of Bull's Bay light Station (epicentral distance of 25 miles) shook so 

strongly that the lens fell from its pedestal. The 

150-foot-high Cape Romain Light Stat~~n (epicentral distance of 40 miles) experienc~d no 

damage to the tower, although its vibration was 

very great. Everything on the shelves was 

thrown down, as well as a trap door tr<:tt leaned 

at an angle of 45°. The Hunting Island Light 

Station, also about 40 miles from the epicenter, 

26 
shook so violently that the two assistant keepers in the watchroom at the top could not stand 

up without holding onto the railing. The second 

assistant keeper was thrown to and fro from the 

dome to the balcony railing, near the top of the 

121-foot tower. At the Bloody Point Range 

Lights (epicentral distance of 71 miles), the 

shock lasted from 1 to 2 minutes and was accompanied by a roaring noise, as a cannonading. Loose things on all sides tumbled about. At 

Tybee Island Light Station, Georgia, at the entrance to the Savannah River (distance of 81 

miles), the first shock continued for about 90 

seconds and was accompanied by a heavy, 

rumbling noise, similar to thunder underneath. 

The wall of the 134-foot-high tower was 

cracked about midway, where it was 6 feet 

thick. The lens, weighing about 1 ton, was 

moved 1112 inches to the northeast. Finally, at 

the Cape Fear Light Station on the North Carolina coast (epicentral distance of 125 miles), the 

shocks were strong enough to crack and break 

glass lamp chimneys in the tower. 

27 
CHAPTER 6 

Origin Time + 1 Minute-120 Miles Distant 

At 120 miles (fig. 16) from the epicenter, Augusta, Georgia, strongly felt the impact of the 

seismic vibrations. Interestingly, the reports 

from that city deal extensively with the response of the citizenry. The Savannah Morning 

News (p. 2, 8) of September 2, 1886 (Armbruster and Seeber, 1984), gave a September 1 

communication from Augusta citing " ... two 

ladies lie at the point of death from fright"; and 

" ... many ladies fainted and thousands of men 

were completely unnerved. The citizens remained in the streets all night." 

The following paragraphs from Dutton (1889, 

p. 328-329) comment on the pronounced psychological effects at Augusta as well as the 

structural damages suffered there: 

"Thus Augusta, in Georgia, just beyond the 100-

mile circle, was shaken with great violence. Many 

buildings were seriously damaged. At the arsenal 

two heavy walled buildings used as officer's quarters were so badly shattered that reconstruction 

was necessary. Many cornices were dislodged and 

it is estimated that more than a thousand chimneys 

were overthrown. People residing in brick 

dwellings refused for several days to enter them, 

and found lodgings in wooden houses or camped 

in the streets and gardens. So great was the alarm 

felt, that business and society were for two days as 

fully paralyzed as in Charleston. Every one was in 

a state of apprehension that the worst was yet to 

come and the only thing to be thought of was 

safety. Indeed, among all the large cities of the 

South the general tenor of the reports indicates 

that Augusta stands next to Charleston in respect 

to the degree of violence of the shocks and the 

consternation of the people." 

"Augusta is built in close proximity to the contact 

of the newer and older strata, and starting from 

that city it will be of interest to follow this line of 

contact northeastward. In detail the course is more 

or less sinuous. A few miles to the northeast of Augusta is a little railway station named Langley, 

where a small tributary of the Savannah River has 

been dammed to secure water power. The ground 

in this neighborhood, which is a loose s':'lil thinly 

covering harder rocks below, was in mi'ny places 

fissured by the earthquake and opened in many 

cracks, some of which were several inches in 

width. A number of large cracks passed through 

the dam, opening passages for the water in the 

reservoir, which quickly enlarged the fissures. The 

country below was quickly aflood. The railway 

track was swept, and before warning cc•Ild be 

given a passenger train ran into the flood and 

upon the broken track, where it was wrecked, 

with some loss of life. In this neighborhood the 

towns of Bath, Graniteville, and Vaucluse, which 

stand upon outcrops of crystalline rocks. report 

shocks of very great severity. Still farther to the 

northeastward, Batesburg, Leesville, and Lexington give similar reports. Passing beyond Columbia 

along the same line of contact, we find reports of 

very violent shocks at Blythewood, Camden, 

Chesterfield, and Cheraw." 

The Savannah Morning News (Armbruster 

and Seeber, 1984) report also noted tl'<:tt 

" ... the most severe damage was don~ on the 

Sand Hills in Georgia and in Aiken County, 

South Carolina." Specific localities mentioned 

were Langley and Bath, just across the Savannah River from Augusta about 6 miles to the 

east. "At Langley, on the South Carolina Railroad, 15 miles from here [Augusta, Georgia] 

and 125 miles from Charleston, the earthquake 

destroyed the mill dam, and the water washed 

away the roadbed. A train dashed into the 

flood, and the engineer and fireman vrere 

drowned. The engine is now 40 feet under 

water." Dutton (1889, p. 504) reported, "Houses 

badly shaken and glasses broken; dans broke 

loose destroying 1,000 feet of railroad; terrible 

suffering among the inhabitants." The. effects at 

the Langley, South Carolina, locale were assigned X on the Modified Mercalli Intensity 

Scale (MM) (Bollinger and Stover, 1976). 

At the neighboring community of Bath (about 

2 miles southeast of Langley) " ... a nE',:JrO 

woman was crazed with fright, and is now 

28 
roaming the woods laughing and shouting hysterically" [Savannah Morning News, as quoted 

in Armbruster and Seeber (1984}). Dutton 

(1889, p. 497} reported, uExtremely violent 

shock, producing general consternation and 

alarm; houses swayed, walls cracked, chimneys 

broken, clocks stopped." Bollinger and Stover 

(1976) assigned a MM VII at Bath. 

ing) cracked, and chimneys were thrown down 

(Dutton, 1889, p. 496, 501). 

MM VII levels of shaking also were observed 

at nearby Aiken and Edgefield, South Carolina. 

Houses were shaken violently, walls (plasterThe abovementioned communities an~ located to the west-northwest of the epicenter. To 

the north, Cheraw and Bennetsville, South 

Carolina, experienced MM VIII effects. Chimneys were demolished or toppled, build;ngs 

rocked and windows were broken. At Cheraw, 

the shock lasted 2 minutes and was pre~eded 

and followed by a rumbling noise, and the 

shaking was severe enough to cause pe:ople to 

75° 

\--·-

1---·('·~, \ ' 

L -------·-'\.. \ 

.-· .s''-...... _<.. 

'\-- \ 

) i .) 

5/ I )\ ~---f \-·- -·---·--( \ / ·-·1~7/;~\..... \ ·~ \ i . ( 1/ l \.-. 

( ' 1 N ·-..... \ -""., _ _.... ) .r· I \) .r-"' ')· I 

! l I ·L/ \, .f 

I ., jrJ"'..J j\.-·/ 

I \ ~ j --·- 1 v" -...J ~--·-;;·-·-·- . d ..r-·-·-·---·-· r !\- -·- - - - 2__/-- /.f/. 

\ I / ./·-·-·"""·-·-Cheraw 

i 1----~-------,----·-c.-.... •winnsb~ro 

1 ~/ I · Edgefield • ) 

/ { ! \ Augusta -~iken • 

·: ~ I \ Charleston 

1·--------i ! \ . ( I \ . ~ f l . ( \. \ . 

I {._ -·-·1 \ 

( 

0 100 200 300 

I I I I I I I I 

400 MILES 

I 

0 100 200 300 400 KILOMETERS 

Figure 16. Cities and towns at an epicentral distance of approximately 120 miles. 

29 
have difficulty in standing up. Public reaction 

varied from great excitement to panic. Many 

individuals remained outdoors the entire night 

(Dutton, 1889, p. 497, 500). 

To the southwest, near the coast, Darien, 

Georgia, reported one small house demolished 

(MM VII), while nearby Jesup, Georgia, reported no damage but general alarm of the 

populace (MM V) (Dutton, 1889, p. 425, 427). 

Finally, Winnsboro, South Carolina (northwest), 

and Fair Bluff, North Carolina (northeast), experienced MM intensity VI effects-some chimneys were overthrown or dislodged and "general consternation" was experienced among the 

residents (Dutton, 1889 p. 509, 477). 

Although observed average intensity at a distance of 120 miles was between MM VII and 

VIII, some towns, as noted, had values as low 

as MM V (Jesup, Georgia) and others as high 

as MM X (Langley, South Carolina). Most 

likely, these large departures from the average 

resulted from local site conditions; that is 

hardrock or soft, water-saturated soil. 

Predicted values (Nuttli and others, 1984) of 

the ground motion at an epicentral distance of 

120 miles are effects of MM VII to VIII, maximum horizontal acceleration of 26 incra.s per 

second per second, and maximum horizontal 

velocity of 5 inches per second. The peak velocity value is more consistent with the intensity and damage experienced than is t'le peak 

acceleration value. The relatively low value of 

peak acceleration results from the fact that at 

distances of 120 miles, the high frequency 

waves that are associated with large values of 

acceleration are attenuated more severely than 

the lower frequency waves; that is, low frequency waves have larger ratios of peak 

ground velocity to peak ground acceleration 

than do high frequency waves. 

30 
CHAPTER 7 

Origin Time + 2 Minutes-240 Miles Distant 

At an epicentral distance of 240 miles 

(fig. 17), the level of ground shaking continued 

to cause panic among the people (Dutton, 

1889, p. 476, 478, 479, 424, 429)- 11 ••• a state of 

terror and excitement; people left their houses 

and many stayed in the streets all night" 

[Beaufort, North Carolina], II • •• streets rapidly 

filled with people, screams of frightened persons could be heard (Raleigh, North Carolina). 

II • •• rushed frightened from their houses into 

the streets; terror-stricken men, women and 

children, in night dress, crowded the streets in 

a moment; a number of ladies fainted 

(Asheville, North Carolina). II • •• people startled 

by the shocks and thrown into the greatest 

alarm" [Greenville, North Carolina], II • •• people 

rushing into the streets in indescribable confusion, each looking for an explanation from the 

others; the streets at 10 o'clock are full of people, who fear to return to their houses [Atlanta, 

Georgia], and II • •• those who had retired 

were aroused by the trembling of their houses 

and the falling of plaster; it has created 

much excitement and uneasiness (Valdosta, 

Georgia)." 

Buildings and household items (mirrors, pictures, lamps, dishes, window glass, and so 

forth) were shaken (a level of VIII or less on the 

Modified Mercalli Intensity Scale (MM)]. Atlanta, in northern Georgia, reported one house 

(on Marietta Street) II • •• shaken to pieces," all 

the chimneys fell from the six-story Constitution building, and all over the city, window 

glass was broken, chimneys were knocked 

down, and dishes and glasses were smashed to 

pieces (Dutton, 1889, p. 424). However, 

Valdosta, to the south-southeast and near the 

Georgia-Florida border, reported only falling of 

plaster (MM VI) (Dutton, 1889, p. 429). Within 

Florida, Gainesville's buildings were shaken 

vigorously (MM V) and with an accompanying 

high level of sounds-II A prominent citizen 

jumped from bed, seized a gun and ran out to 

see who was upsetting his house." (Dut':on 

(1889, p. 419) quoting Florida Times Union). 

Reported from the II country people" (pr~~­

sumably those living outside of the city of 

Gainesville) was the development of a ~'large 

hole" (Dutton, 1889, p. 419). At coastal Daytona 

Beach (then Daytona), a low rumbling was 

heard and a report that II • •• artesian or flowing 

wells [were] greatly agitated" was rece1ved 

(Dutton, 1889, p. 418). 

Across the entire State of North Carol;na, effects ranged from MM V to VII. Examples of 

the highest levels were experienced at Beaufort 

(Dutton, 1889, p. 497) on the coast, Rale.igh 

(Dutton, 1889, p. 4 79) in central North Carolina, 

and Waynesville (Dutton, 1889, p. 480) in the 

extreme southwestern part of the State. The 

seismic waves at those locations caused chimneys to be overthrown or have their top~ 

shaken off, some walls to crack, plaster.ng to 

be thrown down, buildings to rock, and some 

floors to break II • • .loose from their sup:')orts." 

Additionally, church bells rang, clocks rtopped, 

mirrors and pictures were thrown from walls, 

and lamps were overturned. At Asheville, 

North Carolina (Dutton, 1889, p. 476), houses 

were shaken violently, but no buildings were 

~·shaken down" (MM VI). At Black Mountain 

(12 miles to the east of Asheville), the vibrations were accompanied by loud explosive 

sounds and heavy rumblings, and large masses 

of rock were dislodged from several ste~p 

slopes and rolled into the valleys below (Dutton, 1889, p. 476). 

In discussing the MM V to VII effectf of the 

earthquake throughout the State of North Carolina, Dutton (1889, p. 329-331) commented on 

their azimuthal asymmetry; that is, gen~rally a 

II notable difference" between effects in the 

eastern, coastal region part of the State and 

those in the Piedmont and mountain (Blue 

Ridge and Valley and Ridge provinces) region 

31 
was reported. Dutton (1889, p. 329) stated, "It 

was notably less forcible in the coastal plain. At 

coastal cities (Beaufort was an exception) and 

at lighthouses, the reported levels of damage 

and alarm of the residents was much less than 

those described above for such interior locations as Raleigh and Asheville" (Dutton, 1889, 

p. 329). In general, Dutton (1889, p. 327) noted, 

"The decline of intensity is abnormally rapid 

along the coast for the first 150 or 200 miles." 

Dutton's intensity map (fig. 1) was o1ntoured 

in a highly generalized manner so as to depict 

the broad, regional pattern of effects. Thus, the 

detailed variations he described above are not 

shown. However, Bollinger's (1977) reinterpretation of Dutton's intensity data for the 1886 

earthquake included such detailed cortouring 

for the effects in South Carolina as well as 

throughout the country (fig. 4). The az;muthal 

complexity of the earthquake's effect is seen 

clearly in these detailed maps. 

'-·-·\· \ . 

L .-----·-·.-..\.. ~ ·- s'-........ <. '\.·)-·-·-·\ \ \ 

. I -c·-· \ > 

./ \ \ ~ 5 i \ f\ --~------·~( ,-·-·-·-·-·--! \ \ / ·-·-r;/...,r~"" ·~ \ i r ./ l 

< ., i l·-". !'1 ,/ -~ \I \ ,..,.,. '-·._..·'!) i 

! l I ...;·'-/ \, .i 

I , t,.., . ......,. j\ .. -·/ .-·-

! \ ? ..1 .-·-·-·- ' 'y/·-..1 ~--·---·-·------ ., d_._ .. r-·-·-·-·-·-· _,..? Durham. • _Greenville 

\-·-·-·-·-·-·2._./ ,.....f~Asheville •BRalefJgh~ . W . ·~ eau or ., f ayne7vJ1Ie -~--·- ._.-.7 . 

I

. i .-·-·-·-=-·-·-· ( ·,. 240 mtles (-·-·----. \ ·-.... ' 

I

. r I . '-

I

. / i Atl~nta• ·"· ) . \ ' 

·: ~ ! \ \{·charleston 

1·-·-·-·-·i I · \ . ( i ) \ i · I ~ / \ ( 

\ {. \ -·-·-·-\..-. • V9J.9.~sta ., ·-·-·-·? \ '). 

( 

0 100 200 300 400 MILES 

I I I I I 

I I I I 

0 100 200 300 400 KILOMETERS 

Figure 17. Cities and towns at an epicentral distance of approximately 240 miles. 

32 
Dutton (1889, p. 329) ascribed this rapid attenuation of the earthquake vibrations as due 

to anomalous absorption by ". . . the vast 

masses of littoral deposit of unconsolidated 

sands, clays, and marls along the Atlantic border and coastal plain .... " This is, in principle, 

a possible explanation. However, another possible cause is related to the radiation pattern 

from the earthquake source itself. Theoretical 

and observational studies of the elastic wave 

energy radiated away from an earthquake fault 

show that such radiation is not uniform in all 

directions. Rather, depending on the detailed 

characteristics and orientation of such seismogenic faults, certain directions have maximum vibration levels, while other directions 

have minimal levels of shaking. 

In his attempts to infer the direction of the 

fault that caused the 1886 earthquake, 

Bollinger (1983) noted that the innermost isoseismal contours (figs. 2, 4) have a northeasterly orientation, and, thus, a causal fault with a 

similar trend could be postulated. However, he 

also noted that the broad, regional pattern of 

intensity (fig. 3) exhibits a pronounced n0rthwesterly lobe. That type of effect could result 

from the surface waves radiated by a no~theasterly trending fault. 

Average values of ground motion at tt. e 240-

mile epicentral distance, as predicted by the 

equations of Nuttli and others (1984), are effects of MM VI to VII, peak horizontal acceleration of 12 inches per second per second (associated with 1- to 2-second period waves}, and 

peak horizontal velocity of 3 inches per second. 

The latter value is slightly below the thr,.~shold 

of damage value (Dowding, 1985), whicl' would 

correspond to dislodging of loose objectr,. such 

as bricks in chimneys, and formation of plaster 

cracks. The long duration of the earthquakeinduced ground motion, as contrasted to the 

short duration of blast-induced ground n1otions 

(Dowding, 1985), likely results in larger damage for earthquake motion of the same ground 

velocity as the shorter duration blast-induced 

ground motion. 

33 
CHAPTER 8 

Origin Time + 3 Minutes-360 Miles Distant 

As vibrations travel away from their source 

area, they tend to decrease in amplitude and 

increase in duration. This can be seen by dropping a pebble into a pool of water. At the point 

of entry, a short-duration, high-amplitude 

"splash" occurs, but, by the time the disturbance reaches the boundary of the pool, a 

"long" train of low-amplitude waves occurs. A 

similar effect occurs in earthquake vibrations 

and is most pronounced in what are termed 

surface waves. These waves travel along the 

surface and uppermost portions of the Earth in 

contrast to body waves, which can penetrate 

into the Earth's deep interior. Earthquake effects at close-in distances generally are ascribed to body waves and high-frequency surface waves, in part because the low-frequency 

surface-wave trains have not developed fully. 

Then, at greater epicentral distances, the surface waves, which have longer periods (lower 

frequencies) and less attenuation in their vibrations, tend to produce the effects observed on 

people and structures. 

At an epicentral distance of 360 miles 

(fig. 18), the motion from long-period surface 

waves was dominant. In Richmond, Virginia, 

the vibrations were felt throughout the city and 

threw some people down. Chimneys and plastering were thrown down, and bricks were 

shaken from houses. The entire population was 

in the street. The swaying of the buildings 

caused hundreds of people to feel slightly nauseated and some to be "rolled from bed" (Dutton 1889, p. 520). At Norfolk, " ... workmen two 

or three stories from the earth felt the shock 

more sensible than those on the ground"; and 

" ... near panic at the Opera" occurred (Ayers, 

1974). Also, the tremors " .. .increased to undulations and trees rustled" (Dutton, 1889, p. 519). 

A duration of 1 minute for the vibrations was 

estimated at White Sulphur Springs, West Virginia, and Cookeville, Tennessee (Dutton, 1889, 

p. 524, 510). In Montgomery, Alabama, large 

buildings swayed, causing inhabitants to leave 

upper floors, while those on the ground floors 

did not feel the vibrations (Dutton, 1889, 

p. 412). In Florida, suspended objectF swung in 

Apalachicola, and sleepers were awakened, 

some with nausea, in Tampa (Dutton, 1889, 

p. 417, 422). 

Pronounced variations in intensity levels at 

these distances can be attributed, at least in 

part, to variations in soil thicknesses and types 

(filled land an extreme case here), groundwater levels, and topography. A number of 

such examples occurred in Virginia and Florida, where ground vibrations were amplified in 

areas of water-saturated soil, filled land, and 

hills. In Norfolk, Virginia, "great excitement" 

was reported in the western, southern, and 

eastern portions of the city, while it was 

"hardly felt" in the northern parts (D'Jtton, 

1889, p. 519). In Richmond, Virginia, the shaking generally was felt in every part o~ the city 

but was especially severe in the western and 

northern areas; most residents were cwakened 

from sleep and ran outdoors while some slept 

through the event. Also in that city, "wildest excitement" was experienced by the "terrorstricken" prisoners at the State Prisor. which 

was situated on a "high hill." About 12 to 15 of 

them broke out of their cells, and the military 

was called out to restore order (Dutton, 1889, 

p. 341, 520). Tampa, Florida, reported that 

" ... a sink formed on the night of August 31 

said to be 100 feet across and 30 feet deep" 

(Dutton, 1889, p. 422). 

Response of animals was reported f:'·om Norfolk-"The rats left dwelling houses and stood 

not on the order of their going" and " ... rats 

deserted houses throughout the city" (Ayers, 

1974); from Apalachicola, Florida, " ... animals 

showed some alarm" (Dutton, 1889, p. 417). 

The response of Mr. George D. Levy of Richmond, Virginia, was reported as (Aye~s, 1974): 

34 
". . .he was crossing Clay Street to his home when 

a sensation overcame him that caused him to stop. 

At first he did not know what it was, but he felt 

very faint. Immediately after he heard a reverberating sound approaching like the echo of a cannon 

shot between two high hills; and, as the sound became louder, the earthquake began to tremble, 

causing the windows in the houses to rattle, and 

the house in which he lives to sway to and fro, not 

with a smooth, regular, undulating motion, but 

with irregular and uneven jerks. Just then the 

noise sounded as if the neighboring houses were 

95° 85° 

0 

I 

'\-

' 

100 200 300 

I I I 

I I I I 

cracking brick by brick and were going to fall. The 

sound gradually died out and seemd to recede up 

Clay Street in a westerly direction. He estimates 

the whole thing lasted about 8 seconds." 

It is possible that the initial perception and 

light-headedness experienced by Mr. Levy 

were caused by the compressional or primary 

(P) waves and (or) by the shear or secor dary 

(S) waves (normally of higher amplitude than 

P waves). The sound and then finally the jolting motions likely resulted from the slo-wer 

400 MILES 

I 

75° 

0 100 200 300 400 KILOMETERS 

Figure 18. Cities and towns at an epicentral distance of approximately 360 miles. 

35 
traveling surface waves (higher amplitude and 

longer period than P and S waves). 

Ayers (1974) also reported an amusing social 

aspect of the earthquake shaking in Richmond. 

A young man called on his girlfriend and, 

when the shock came, it moved their chairs in 

close proximity. The girl's mother came in and, 

not comprehending the situation, gave the couple a lecture. She later had to apologize on 

finding out the truth of the matter. 

The range in the severity of the earthquake 

shaking reported at the 360-mile epicentral distance was considerable. In addition to the 

people-animal-ground responses discussed 

above, Richmond reported people falling, 

bricks shaken from houses, and plaster and 

chimneys thrown down (Dutton, 1889, p. 340, 

520). In Norfolk, residents and workers fled into 

the streets, some chimneys were broken, and 

warehouses were damaged (Dutton, 1889, 

p. 519). Somewhat further away, at Washington, D.C., the disturbance caused considerable 

fright to occupants on upper floors of buildings. 

It caused buildings to shake and furniture to be 

moved around. It generally was felt throughout 

the city and also in Baltimore (Dutton, 1889, 

p. 339-40). Dutton (1889, p. 522) reported that 

at Charleston, West Virginia, " ... the vigor of 

the shocks was somewhat remarkable." A number of chimneys toppled over, houses were 

rocked forcibly and great excitement was experienced with many people leaving their homes. 

By contrast, White Sulphur Springs, West Virginia, reported only that the shaking was very 

perceptible and everybody felt it" (Dutton, 1889, 

p. 524). Houses were "severely shaken" at 

Winchester, Tennessee (Dutton, 1889, p. 514), 

and, in Montgomery, Alabama, buildings 

"rocked and quivered," doors and windows rattled, and some residents fled into the streets 

(Dutton, 1889, p. 412). 

The average gound motions at the 360-mile 

distance, predicted by use of the equation of 

Nuttli and others (1984), are effects of VI on the 

Modified Mercalli Intensity Scale (MJ ·1), peak 

acceleration of 7 inches per second p~r second 

(associated with 2-second period waves), and 

peak velocity of 1.5 inches per second. 

The predicted MM VI effects are somewhat 

higher than those actually observed ~~~cause 

little minor damage of the type that c ccurs at 

MM VI was reported. This suggests that the 

equation of Nuttli and others (1984), 

I(R) = 0.86 + 1.81 mb- 2.3 log10 (R2 + h2)112 - 0.00085 R , 

needs some revision. Changing the lc ')t term to 

-0.0020 R has the effect of making tl'~ calculated intensities at distances of 360 miles and 

greater conform better to observed vclues for 

the 1886 earthquake. The equation was derived 

from data for the most part at distanc?.s of 

180 miles and less, for which the last term has 

relatively little effect on the calculated intensity 

value; that is, at distances of less than 180 

miles, the I(R) value is relatively insensitive to 

the value of the coefficient of R, as the numerical value of the last term is much less than that 

of the four other terms in the equation. 

Modifying the equation above to 

I(R) = 0.86 + 1.81 mb- 2.3 log10 (R2 + h 2)112 - 0.0020 R 

results in a calculated value of MM V to VI at 

the 360-mile epicentral distance. This value 

closely agrees with the observations of the 1886 

earthquake. 

36 
CHAPTER 9 

Origin Time + 4 Minutes-480 Miles Distant 

After 4 minutes and about 480 miles of travel, 

the vibrations generated in the CharlestonSummerville area finally diminished to the 

point where they no longer caused building 

damage. However, light objects were overthrown, chandeliers swayed, pendulum clocks 

stopped, and some larger objects in homes and 

offices were moved several inches. The principal effects from the vibrations were felt in the 

upper floors of tall buildings in the larger cities. 

In Louisville, Kentucky (fig. 19), " ... at the 

Masonic Temple a wild panic occurred and the 

audience made a stampede for the exits" (Dutton, 1889, p. 449, quoting the Associated Press). 

The earthquake generally was felt throughout 

the city, especially in high buildings that were 

rocked violently (Dutton, 1889, p. 449). In 

Wheeling, West Virginia, the vibrations generally were not felt on the streets; however, 

"wild confusion" was experienced in hotels 

where vibrations were felt most distinctly on 

the second and third stories; " ... a meeting 

stampeded and many frightened from buildings ... " (Dutton, 1889, p. 524). 

Nausea and dizziness commonly were reported effects; for example, from residents of 

Louisville, Kentucky, Baltimore, Maryland, and 

Cincinnati, Ohio. Also commonly reported was 

a description of the ground motions as 

"undulatory;" for example, from Louisville, 

Kentucky, Cincinnatti, Ohio, Wheeling, West 

Virginia, and Mobile, Alabama. The duration of 

these undulatory vibrations was long en0ugh at 

the distance to be estimated by people. Estimates ranged from 14 seconds at Wheel~ng, 

West Virginia, to between 20 and 30 seconds at 

Baltimore, Maryland, Louisville, Kentucky, and 

Cincinnati, Ohio, to 1 minute at Clarksville, 

Tennessee. 

The calculated values of gorund motion at 

the 480-mile epicentral distance, using the 

equation of Nuttli and others (1984) witl' the 

modification discussed in Chapter 8, are effects 

corresponding to IV to V on the Modified Mercalli Intensity Scale, a peak horizontal acceleration of 4 inches per second per second (associated with 2- to 3-second period waves), and a 

peak horizontal velocity of 1.1 inches p€~ second. Motions of the upper levels of buildings 

would be amplified over those experienced in 

the ground or at ground level. However, in 

1886, the steel-frame skyscraper had not yet 

appeared. The so-called tall buildings tl'.en 

were generally only a few stories high and 

were constructed of masonry. 

37 
[ 

' L 

\ _/' ,_.- !_-,." 

I i -----·-·----\. \ 

L-· f' -......" \ \ ' ) 

'\·-·-·-· 

., 

(> 

i \·-·-·-·-··/ 

(.i / -jl Wheeling.\ _ ,. -·-·-· \ 

- 1 . ./ Baltimore 

'- \ ( ·~. I 

~ l rl i "') Louisville · 

I l., f,v·--.~"J 

r 

I \ . 

·"':-. /) _) \.. . ....-· 

t/ I 

_._._./..·,/-·-;·-·-·-·-

•Ci;k~ville /./' 

I \ ~ i ·._,J'--' 

!.-·-·-·---·-·- )_._r 

\ Hun~ngdon. .-J· 

/ -·-·"""" i 

i 

I 

0 

I 

0 

/ .,;-' ·-·-·, i,_._._.,.---·-t,_" '·, 

I \ .'\ 

\ ·......._ • Charleston 

';I \r --- \._ ____ J 

100 200 300 400 500 600 MILES 

I I I I I I 

I I I I I I 

100 200 300 400 500 600 KILOMETERS 

Figure 19. - Cities and towns at an epicentral distance of approximately 480 miles. 

38 
CHAPTER 10 

Origin Time + 5 Minutes-600 Miles Distant 

In the 600-mile range, the vibrations from the 

Charleston earthquake were not felt at some locations; for example, Mt. Vernon, Illinois 

(fig. 20). At those locations where the shaking 

generally was felt, considerable variations in 

intensity occurred. In general, the most severe 

effects were on people located on the upper 

floors of tall buildings; panic and nausea commonly were reported. Also, at this epicentral 

distance, ground conditions (soft, watersaturated sediments) favorable to excitation by 

the longer period seismic surface waves appear 

to have exerted considerable control on the 

level of the effects observed. However, obvious 

exceptions did occur; for example, proximity to 

the Mississippi River at New Madrid, Missouri, 

and Memphis, Tennessee, apparently resulted 

in very distinct shaking in New Madrid (Dutton, 1889, p. 462) and a ''violent shock" in 

Memphis (Dutton, 1889, p. 512), whereas the 

shock was felt only by a few people downriver 

at New Orleans, Louisiana (Dutton, 1889, 

p. 348). 

At Newark, New Jersey, there were conflicting reports about the earthquake effects. Dutton (1889, p. 466-67) stated that the earthquake generally was not felt. However, he also 

gave accounts of people being frightened and 

nauseated, of a factory watchman seated in a 

revolving chair having his head knocked 

against the wall, of large factories shaken violently, and of a clock stopped. In addition, he 

reported that earthquake osciallations were felt 

in New Jersey lighthouses. 

Dutton (1889, p. 335-37) noted that the 

tremors in New York City and Brooklyn were 

very light, and, although tens of thousands of 

people noticed them, hundreds of thousands 

did not. The vibrations were felt almost wholly 

in the tall buildings, while people on the 

ground rarely felt them. In particular, the shaking was not reported as being noticed by anyone who was walking. Dutton devoted three 

pages of text to a quotation from the New York 

Herald of September 1, 1886. The following are 

selected excerpts from that quotation: 

39 

"In the city department of the Herald builcing, on 

the third floor, the oscillations were felt with 

alarming distinctness. The waves of motior 

seemed to flow on a line extending from eastsoutheast to west-northwest. The motion was so 

well defined that it was sufficient at each recurrence to press some of the writers who were at 

work against the tables. Electric wires susr~nded 

about the room swayed back and forth. A h~avy 

electric lamp, covered with a screen and standing 

on a slender brass rod, swayed laterally to and fro 

with a sweep of three-quarters of an inch hr more 

than fifty seconds. There were two series o~ vibrations, the first lasting about twenty secondr, Then 

there was an interval of four or five seconds, and 

again a series of stronger oscillations covering perhaps thirty-five or forty seconds. The durab')n of 

this second series was such that persons could 

move about the room watching the manifestations 

of the earth's erratic action." 

"While on the lower floors of the Western Union 

building the shocks were not noticed, away up 

near the roof they created quite an exciterr.ent. In 

the operating room, on the seventh floor, tl'a. vibrations brought the clicking of the instruments to 

a standstill until the tremors ceased. Severed of the 

operators jumped from their seats, supposing that 

the west wall was falling out. No damage '"as 

done to any of the instruments." 

"In the rooms of the Associated Press, on the top 

story, during the minute or less that the shocks 

lasted, desks, tables, and chairs seemed to be 

swaying. The motion was described by all as from 

west to east and back again. It was "a gentle wavy 

sort of a shake," as an operator said, and still one 

that made persons so high up and so far avray 

from the street wish for the moment that they were 

somewhere else." 

"The upper portion of the city was visited 1:=tst 

night by the shock at three minutes to 10 o'clock, 

as nearly as can be judged, the shock lasting for 
one and a half minutes. While it caused the greatest consternation among the residents on the west 

side of the town, the shock, if any, on the east side 

was but slight. During the prevalence of the vibrations people rushed frantically from houses and 

flats into the street, many in night garments, carrying children in their arms." 

Dutton (1889, p. 341, 342, 482, 483) gave the 

following quotations from Cleveland, Ohio, 

newspapers concerning the earthquake effects 

in that city " ... very severe shocks; generally 

felt throughout the city; houses shoo}-, clocks 

stopped, lamps swayed, and light movables 

toppled; occupants of hotels and theC'ters 

rushed frantically into the streets; at the Opera 

House and the Academy of Music the occupants stampeded toward the exits; pl'lstering 

was shaken down, and pictures fell; no damage, although a very general feeling of nausea; 

those in bed fled from their rooms in night 

dress". The ground movements caused chandeliers, doors, pictures, and so forth, to swing. 

75° 

0 100 200 300 400 500 600 MILES 

I 

I I I I I I 

I I I I I I 

0 100 200 300 400 500 600 KILOMETERS 

Figure 20. Cities and towns at an epicentral distance of approximately 600 miles. 

40 
The shaking was not noticed by many on the 

ground floors of tall buildings, but people panicked on the upper floors. The shock seemed 

most severe near the lake shore. A new frame 

home on filled-in earth leaned 3 feet from vertical by settling that resulted from the shaking. 

In Pittsburgh, Pennsylvania (Dutton, 1889, 

p. 328, 492-494), dishes were thrown from 

shelves, clocks stopped, and occupants of 

houses rushed outdoors, screaming in terror. 

The shock appeared to last from about 30 seconds to 1~ minutes and created the greatest 

consternation in hotels and large buildings. 

An Associated Press report concerning Terre 

Haute, Indiana (Dutton, 1889, p. 448), stated 

that plastering was dislodged, and sleepers 

awakened by swaying beds and rattling windows. Many people rushed to the streets, and 

some were nauseated. There was panic among 

a large audience at the Opera House. The oscillations were severely felt over the entire city 

but were not accompanied by a rumbling noise. 

Reports of private citizens from Terre Haute 

(Dutton, 1889, p. 442) indicated that the earthquake shaking was not noticed by a majority. 

At the Rose Orphan Home, 5 of 80 persons felt 

it slightly. Pendant objects were observed to 

swing considerably, and some people reported 

a feeling of dizziness. 

According to Dutton (1889, p. 462), the vibrations were very distinct in New Madrid, Missouri, causing rocking chairs to rock gently. 

The tremor caused little excitement because 

several slight shocks (at this level of shaking) 

that originated on the nearby New Madrid fault 

occurred there each year. (See Chapter 2 for a 

comparative discussion of the effects of the 

1811 New Madrid earthquake at Charleston.) 

Memphis, Tennessee (Dutton, 1889, p. 512), 

experienced a violent shock, causing many 

people to flee into the streets, some in night 

dress. Guests at the Peabody Hotel rushed 

downstairs. The earthquake effects were 

equally severe over the entire city. No scunds 

accompanied the shaking. 

At Vicksburg, Mississippi (Dutton, 1889, 

p. 461), the City Hall, a frail building on high 

supports, rocked so much that the City Council 

was adjourned hastily. The earthquake vras not 

noticed by people outdoors. 

Dutton (1889, p. 333, 348, 352) gave conflicting information about New Orleans, Louisiana. 

In a tabular summary he indicated that the 

earthquake was not felt except by a few people 

who recognized and identified the tremo~s. 

However, in the text of the report he stated that 

the shocks were observed clearly in New 

Orleans but not throughout the remaindE.r of 

Louisiana, except in the northeastern corner. 

He pointed out that a map of the isoseisn1al 

lines showed that they were crowded together 

in the Gulf Coast, which he attributed to increased attenuation of the seismic wave energy 

by the thick Gulf Coast sediments. 

Earthquake vibrations were not felt in Mt. 

Vernon, Illinois (Dutton, 1889, p. 435). 

At the 600-mile epicentral distance, the calculated average ground-motion values, using 

the equations of Nuttli and others (1984), are 

effects of Modified Mercalli Intensity IV, peak 

horizontal ground acceleration of 3.6 ind'o.s per 

second per second, and a ground velocity of 

0.8 inch per second. 

41 
CHAPTER 11 

Origin Time + 6 to 8 Minutes-720 Miles Distant 

The chief cities at an epicentral distance of 

approximately 720 miles are Buffalo, New 

York, Chicago, Illionois, and St. Louis, Missouri 

(fig. 21). In Buffalo (Dutton, 1889, p. 471}, some 

sleepers were awakened by a sound as of a 

heavy wagon passing. Beds shook, and windows rattled slightly. In Chicago (Dutton, 1889, 

p. 431-433}, the earthquake generally was not 

felt on the ground-floor level but was quite noticeable on upper floors, which shook perceptibly and caused people to rush outdoors. Windows banged in their frames, and buildings 

quivered. In the Tremont House Hotel, a large 

skylight cracked. In a "flat" (2- or 3-story brick 

apartment with a flat roof), plastering was 

thrown from the ceiling, and the occupants became nauseated. In several rooms of the Beaurivage Building, plaster was shaken down from 

walls and ceilings. In some houses, doors 

swung open and shut, and pictures moved from 

walls. In St. Louis (Dutton, 1889, p. 462), a very 

distinct, but not violent, shock was felt. Pictures 

swung, and tables swayed. Some people, particularly in high buildings, felt dizzy and were 

frightened badly. Guests in upper rooms of 

hotels rushed downstairs. 

In New England the earthquake was felt at 

distances beyond 720 miles. In Boston (780 

miles}, a tremulous movement was felt distinctly in the fifth floor of a tall, narrow building; the shaking was scarcely perceptible except in upper stories of lofty buildings (Dutton, 

1889, p. 455). The shaking was felt slightly at 

several locations in New Hampshire and Vermont, at a distance of 840 miles. The earthquake also was felt at large distance;;- in the 

Midwest, very perceptibly in Milwaukee, Wisconsin (780 miles) (Dutton, 1889, p. 526-527), 

and noticeably in the eastern Iowa c~.ties of 

Dubuque, Davenport, Burlington, and Keokuk 

(840 miles) (Dutton, 1889, p. 332-333). An undulatory motion was observed at GrE'~n Bay, 

Wisconsin (840 miles) (Dutton, 1889, p. 525). It 

also was felt unmistakably on the islands of 

Bermuda and Cuba (840 miles) but vras unnoticed in the islands of the West Indie;-. approximately 1,000 miles away (Dutton, 18?9, p. 333). 

Therefore, the average radius of perceptibility 

was about 840 miles, slightly less the-n the 

1,000 miles reported by Dutton (1888, p. 333). 

At the 720-mile epicentral distance, the formulas of Nuttli and others (1984), with revision 

of the intensity equation as noted in Chapter 8, 

give the following estimates of the ground motion: effects of III to IV on the Modified Mercalli Intensity Scale, a maximum hor.zontal acceleration of 2.5 inches per second p~r second 

(associated with 3-second period waves), and a 

peak horizontal velocity of 0.6 inch ro.r second. 

On the third to fifth floors of buildings at the 

720-mile distance, the maximum velocity must 

have been three to four times the mnximum 

ground velocity (about 1.6-2.4 inche;- per second) to produce the effects observed. 

42 
0 

I 

0 

1 00 200 300 400 500 

I I I I I 

I I I I I I I 

600 

I 

100 200 300 400 500 600 700 KILOMETERS 

( 

I 

l. 

\ \-·- /~ • Al~an~ _ ·=-'· 

. ·- \ ...... Buffalo • Hartford ----~ . . -·-· \. \. L.-·- i' ......_< 

Figure 21. Cities and towns at an epicentral distance of approximately 720 miles. 

43 
CHAPTER 12 

Concluding Remarks 

A number of features of the 1886 earthquake, 

in addition to being the largest historic earthquake in the United States east of the Appalachian Mountains, were noteworthy. Even 

though the epicentral area had experienced 

minor seismic activity before its occurrence, 

nothing in the previous earthquake history nor 

in the topography suggested that an earthquake with a surface-wave magnitude (Ms) of 

7. 7 could happen in Charleston. The surficial 

geology showed none of the characteristics that 

can be observed in the more earthquake-prone 

regions of the Western United States. Although 

it is true that many earthquakes do not produce 

surface faulting, large-magnitude earthquakes 

of shallow focal depth usually do. However, the 

1886 earthquake, like the other very large 

magnitude earthquakes in eastern North America, namely the 1663 St. Lawrence River valley 

earthquake and the 1811-12 New Madrid fault 

earthquakes, exhibited no surface faulting even 

though the former produced extensive rockfalls 

and landslides and the latter caused landslides, 

rifting of the soil, and sand extrusions over a 

large area of the Mississippi and Ohio River 

valleys. 

The second noteworthy feature concerns the 

large area of perceptibility and the large distances at which damage occurred. Dutton 

(1889, p. 333) stated that " ... the area within 

which the motion was sufficient to attract the 

attention of the unexpectant observer would 

thus be somewhat more than circumscribed by 

a circle of a thousand mile radius." This maximum perceptible distance was much larger 

than the 225-mile value for the 1952 Kern 

County, California, earthquake, which had a 

similar surface-wave magnitude, namely 

Ms = 7.7 (Coffman and von Hake, 1973). As 

noted in Chapters 10 and 11, minor damage to 

upper floors of buildings occurred as far away 

as New York City (600 miles) and Chicago (720 

miles). 

The large felt and damage areas in the Eastern United States, compared to Western United 

States earthquakes of the same magnitude, can 

be explained readily in terms of differences in 

anelastic attenuation. Singh and Herrmann 

(1983) presented a map of 1-second period Q 

values for the United States. The Q 'Talues are 

a measure of attenuation, with large attenuation (rapid decrease of vibrations with distance 

from the source) corresponding to low Q 

values. Their map of Q values shows that, in 

general, the area of the United State;;- east of 

the Rocky Mountains has much sma1ler attenuation of 1-second period seismic wave energy 

than does the area to the west of the Rockies. 

The differences in Q values are sufficient to 

provide a quantitative explanation of the observed differences in areas of perceptibility and 

of damage for the two portions of the United 

States. 

Let us return to the question of the: lack of 

surficial geological evidence of earthquake activity in the Charleston area. Although extensive geological investigation of the area to determine the cause of the 1886 earthquake has 

been carried out since 1970 by many highly 

competent geologists and geophysici~1:s, only in 

the past few years have definitive re~ults been 

forthcoming. Obermeier and others (1985a, b) 

found evidence of multiple generations of prehistoric sandblows at several sites in and 

slightly beyond the meizoseismal area of the 

1886 earthquake. Carbon-14 dating showed 

that strong shaking caused at least o!le set of 

sandblows near Hollywood, South Carolina 

(about 17 miles west of Charleston}, 3,000 years 

ago, and geologic evidence showed that several 

episodes of strong shaking probably occurred 

near Hollywood caused by moderate to large 

earthquakes within the past 10,000 to 12,000 

years. Talwani and Cox (1985) also studied 

shallow sand structures at Hollywood and identified five other sites in South Carolina with po44 
tential paleoliquefaction features. They concluded, "Field evidence and radiocarbon dates 

suggest that at least two earthquakes of magnitudes (mb) greater than 6.2 preceded the 1886 

event in the past 3,000 to 3,700 years. The evidence yielded an initial estimate of about 1,500 

to 1,800 years for the maximum recurrence of 

destructive, intraplate earthquakes in the 

Charleston region." Talwani and Colquhoun 

(1985) concluded from shallow stratigraphic investigations in the Charleston-Summerville 

area that the northwest-striking Ashley River 

fault is related to a graben. They stated that the 

fault, which is 2 to 4 miles deep and less than 6 

miles long, possibly is associated with a 25-

mile-long, 11-mile-wide, and, at least, 400-footdeep northwest-trending graben. The northwest-trending faults of the graben are parallel 

to and embrace the Ashley River fault, and the 

pattern of isoseismals of current felt earthquakes follows the outline of the graben. They 

also concluded that the 6- to 8-mile-deep 

northerly striking Woodstock fault may be associated with a Triassic basin. 

In Chapter 2, focal mechanisms of recent 

South Carolina earthquakes were discussed. 

The shallow (less than 5-mile-deep) microearthquakes and earthquakes appeared to be 

associated with reverse motion on a northweststriking fault. One of the possible fault planes, 

as obtained from primary-wave, first-motion 

studies, is near vertical (dip of 78°), and the 

other is near horizontal (dip of 12°). From the 

discussion above, these earthquakes may be 

occurring on the Ashley River fault. The 

hypocentral location and focal mechanism of 

the somewhat deeper (6-8 miles) earthquakes 

indicate strike-slip motion on a vertical fault 

plane that strikes approximately north to south, 

corresponding to the Woodstock fault mentioned above. As discussed in Chapter 2, some 

of the reports in Charleston concerning the timing of the wave arrivals and the directions from 

which the waves appeared to arrive could be 

explained by rupture proceeding from north to 

south for a distance of 16 to 19 miles, beginning at a point about 3 miles to the southeast of 

Summerville and stopping at a point a few 

miles to the northeast of Adams Run. This is 

one line of evidence that can be used to favor 

selection of movement on the Woodstock fault 

as being the cause of the 1886 main shock. 

Other points that tend to support this speculative conclusion include the cluster of very high 

intensities around Adams Run on Dutton's 

(1889, p. 309) map (fig. 2), which would correspond to the location of the stopping point of 

the fault rupture, and the fact that an earthquake of Ms = 7.7 would have to be at least 12 

miles deep for it not to rupture the Earth's 

surface. 

The intensity data at larger distances clso 

can be used to speculate about the focal mechanism. For this study, synthetic seismograms 

have been constructed for epicentral distances 

of 180 and 360 miles at a number of azin1uths 

for earthquakes of seismic moment and fault 

rupture area believed appropriate from t:'-le 

1886 main shock. Three focal mechanisms were 

simulated in this exercise. The first model. corresponds to horizontal or strike-slip motion on a 

vertical fault plane that strikes north to S')uth. 

The second model corresponds to dip-slip motion on a fault plane striking northwest to 

southeast and dipping at an angle of 78°. The 

third model also has dip-slip motion on a fault 

plane striking northwest to southeast, but the 

angle of dip is 12°. At the 180- and 360-nile 

distances, the first model predicts maximum 

horizontal motion, for wave periods near 1 second, in a northerly direction and motions approximately only one-third as large to the west. 

Model 2 predicts largest motions to the northnorthwest, and substantially smaller motions to 

the north, north-northwest, and north-no:'theast. 

Inspection of figure 3 in Chapter 2 showr that, 

at large epicentral distances, the isoseisn1als 

are extended (larger intensities at a fixecl. distance) in directions from slightly east of north 

to northwest and are shortened (smaller intensities at a fixed distance) in the directions from 

west to southwest. Taken alone, this infoTmation would favor Models 1 and 2 as possible 

focal mechanisms and rule out Model 3. However, attenuation effects also must be considered before coming to such a conclusion. 

Singh and Herrmann's (1983) map of the 

1-second period Q value for the United 5·~ates 

shows that, in the Gulf and Atlantic Coar:tal 

Plains, the attenuation of 1-second period 

waves is notably larger than those in the 

interior of the Eastern United States. This phenomenon, which was first proposed by D'ltton 

(1889, p. 329) for the fall-off of intensity along 

the Atlantic coast at distances of 150 to 200 

miles, also could explain the shape of the isoseismals at large distances in figure 3 in Chapter 2, if the radiation of wave energy fron the 

1886 main shock was the same in all directions. 

However, by taking into account the effects of 

45 
regional differences in attenuation and the effects of azimuthal differences in radiation of 

wave energy, the synthetic seismograms of 

Model 3 appear to be less compatible with the 

intensity data at large distances than those calculated using Models 1 and 2. On that basis, 

Model 3 might be ruled out, or at least given 

less weight than the other models. The intensity distribution at large distances is, by itself, 

incapable of distinguishing between Models 1 

and 2. 

As pointed out in Chapter 7, Bollinger (1983) 

noted that the innermost isoseismal curves, corresponding to VI to X on the Modified Mercalli 

Intensity Scale (MM), of the 1886 main shock 

have a northeastwardly orientation, which 

could be postulated to be the trend of the 

causal fault. In Chapter 2 and above other evidence in the area near the epicenter that appears to support the choice of the so-called 

Woodstock fault as the causative fault was 

given. However, all such evidence is circumstantial rather than conclusive. At this time, we 

speculatively associate the 1886 earthquake 

with strike-slip motion on a north- to northeast-striking fault plane of predominantly vertical orientation but do not rule out the possibility of the alternate explanation of reverse motion on a steeply dipping fault plane that 

strikes northwest to southeast. 

Finally, the intensity distribution presented 

by Bollinger (1977), which is reproduced as figure 3 in Chapter 2, is consistent with the seismic source parameters estimated by using relations proposed by Nuttli (1983) and with the 

attenuation relations proposed by Nuttli and 

others (1984) for South Carolina earthquakes; 

that is, the 1886 main shock intensity values 

could result from an earthquake having a 

body-wave magnitude of 6.7, a surface-wave 

magnitude of 7.7, a seismic moment of 4 x 1026 

dyne-centimeters, a rupture length of 16 to 19 

miles, and rupture width of 9 to 12 miles, with 

the coefficient of anelastic attenuation of 1-

second period earthquake waves being about 

0.0013 per mile. The latter value corresponds to 

an apparent Q value of 1-second period waves 

of 1,100, if the waves travel with a velocity of 

2.1 miles per second. Further study, in the form 

of detailed numerical modeling of the source 

rupture dynamics and of the transmission 

medium, undoubtedly will provide a more complete understanding of this very interesting 

earthquake. 

Acknowledgments 

We are indebted to those workers vrhose 

studies have provided the basis of this work, 

beginning with and especially the late Capt. 

Clarence E. Dutton, whose encyclope'lic 1889 

report remains the primary reference on the 

earthquake. We have quoted and borrowed 

from his report liberally and strongly recommend its reading to all who have more than a 

cursory interest in the subject. 

The idea for the present monograpl' originated with Dr. Charles C. Thiel, Jr., of Forell/ 

Elsesser Engineers, Inc., in a discussion with 

Dr. James E. Beavers of Martin MariE.tta Energy Systems, Inc., and Dr. Walter W. Hays of 

the U.S. Geological Survey, all of whom have 

given their enthusiastic support to the authors. 

Dr. Hays and Dr. Roger M. Stewart of the U.S. 

Geological Survey provided valuable review 

and criticism of the manuscript. Mr. J\1ichael 

Jost, a graduate student at Saint Loui~ University, did the computer simulation of tl'o. earthquake rupture process. Support for the study 

was provided under U.S. Geological ~llrvey 

contract 14-08-0001-22053. 

46 
REFERENCES CITED 

Ackerman, H. D., 1983, Seismic-refraction study in 

the area of the Charleston, South Carolina, 1886 

earthquake, in Gohn, G. S., ed., Studies related to 

the Charleston, South Carolina, earthquake of 

1886-Tectonics and seismicity: U.S. Geological 

Survey Professional Paper 1313, p. F1-F20. 

Armbruster, John, and Seeber, Leonardo, 1984, The 

1886-89 aftershock zone of the Charleston, South 

Carolina, earthquake initiated a new pattern of 

seismicity in the southeastern U.S. (abstract): 

Earthquake Notes, v. 55, no. 3, p. 11. 

Ayers, R. L., 1974, A comparison of macroseismic 

and microseismic ground motion in Virginia: M.S. 

thesis, Virginia Polytechnic Institute and State University, Blacksburg, Va, 198 p. (An article of the 

same title appears in Pure and Applied 

Geophysics, 1975, v. 113, no. 4, p. 695-711.) 

Bollinger, G. A., 1977, Reinterpretation of the intensity data for the 1886 Charleston, South Carolina, 

earthquake, in Rankin, D. W., ed., Studies related 

to the Charleston, South Carolina, earthquake of 

1886-A preliminary report: U.S. Geological Survey Professional Paper 1028, p. 17-32. 

--- 1983, Speculations on the nature of seismicity 

at Charleston, South Carolina, in Gohn, G. S., ed., 

Studies related to the Charleston, South Carolina, 

earthquake of 1886-Tectonics and seismicity: 

U.S. Geological Survey Professional Paper 1313, 

p.T1-T11. 

Bollinger, G. A., and Stover, C. W., 1976, List of intensities for the 1886 Charleston, South Carolina, 

earthquake: U.S. Geological Survey Open-File Report 76-66, 31 p. 

Campbell, K. W., 1984, An empirical assessment of 

near-source strong ground motion for a 6.6 mb (7.5 

Ms) earthquake in the eastern United States: 

Lawrence Livermore National Laboratory Report 

UCID-20083 and U.S. Nuclear Regulatory Commission Report NUREG/CR-3839, 59 p. 

Coffman, J. L., and von Hake, C. A., eds., 1973, 

Earthquake history of the United States: Publication 41-1, U.S. Department of Commerce, National 

Oceanic and Atmospheric Administration, Washington, D.C., 208 p. 

Dewey, J. W., 1983, Relation of instrumentally 

recorded pre-1974 earthquakes in the South Carolina region, in Gohn, G. S., ed., Studies related to 

the Charleston, South Carolina, earthquake of 

1886-Tectonics and seismicity: U.S. Geological 

Survey Professional Paper 1313, p. Q1-Q9. 

Dowding, C. H., 1985, Blast vibration monitcring and 

control: Prentice-Hall, Englewood Hills, N.J., 

297 p. 

Dutton, C. E., 1889, The Charleston earthquake of 

August 31, 1886: U.S. Geological Survey, Ninth 

Annual Report 1887-88, p. 203-528. 

Lawson, J. E., Jr., 1985, Seismicity at the Me~rs fault 

(abstract): Earthquake Notes, v. 55, no. 1, p. 2. 

Nuttli, 0. W., 1983, Average seismic sourceparameter relations for mid-plate earthquckes: 

Seism~logical Society of America Bulletin, v. 73, 

no. 2, p. 519-535. 

Nuttli, 0. W., Bollinger, G. A., and Griffiths, D. W., 

1979, On the relation between modified M.ercalli 

intensity and body-wave magnitude: Seisnological 

Society of America Bulletin, v. 69, no. 3, p. 893-

909. 

Nuttli, 0. W., and Herrmann, R. B., 1984, Ground 

motion of Mississippi valley earthquakes: Journal 

of Technical Topics in Civil Engineering, American Society of Civil Engineers, v. 110, no. 1, p. 54-

69. 

Nuttli, 0. W., Rodriguez, Rene, and Herrmann, R. B., 

1984, Strong ground motion studies for So·1th Carolina earthquakes: Lawrence Livermore National 

Laboratory Report UCRL-15594 and U.S. Nuclear 

Regulatory Commission Report NUREG/CR-3755, 

88 p. 

Obermeier, S. F., Weems, R. E., Gohn, G. S., and 

Rubin, Meyer, 1985a, Distribution and recurence 

of prehistoric earthquakes near Charleston (abstract): Earthquake Notes, v. 55, no. 1, p. 25. 

Obermeier, S. F., Gohn, G. S., Weems, R. E., Gelinas, 

R. L., and Rubin, Meyer, 1985b, Geologic evidence 

for recurrent moderate to large earthquakes near 

Charleston, SC: Science, v. 227, p. 408-411. 

Ramelli, A. R., and Slemmons, D. B., 1985, Surface 

effects and scarp morphology, Meers fault. Oklahoma (abstract): Earthquake Notes, v. 55, no. 1, 

p. 1. 

Richter, C. F., 1935, An instrumental magnit·1de 

scale: Seismological Society of America Bulletin, 

v. 25, no. 1, p. 1-32. 

Robinson, Andrew, and Talwani, Pradeep, 1983, 

Building damage at Charleston, South Carolina, 

associated with the 1886 earthquake: Seismological Society of America Bulletin, v. 73, no. 2, 

p. 633-652. 

47 
Singh, Sudarshan, and Herrmann, R. B., 1983, Regionalization of crustal coda Q in the continental 

United States: Journal of Geophysical Research, 

v. 88,no. B1,p. 527-538. 

Taber, Stephen, 1914, Seismic activity in the Atlantic 

Coastal Plain near Charleston, South Carolina: 

Seismological Society of America Bulletin, v. 4, 

no. 3, p. 108-160. 

Talwani, Pradeep, 1982, Internally consistent pattern 

of seismicity near Charleston, South Carolina: Geology, v. 10, p. 654-658. 

Talwani, Pradeep, and Colquhoun, D. J., 1985, Near 

surface evidence for buried seismogenic faults in 

the Charleston, South Carolina region (abstract): 

EOS, American Geophysical Union Transactions, 

v. 66, no.46,p. 970. 

Talwani, Pradeep, and Cox, John, 1985, Paleoseismic 

evidence for recurrence of earthquakes near 

Charleston, South Carolina: Science, v. 229, 

p. 371-381. 

Tarr, A. C., 1977, Recent seismicity near Charleston, 

South Carolina, and its relationship to the August 

31, 1886 earthquake, in Rankin, D. W., ed., Studies 

related to the Charleston, South Carolina, earthquake of 1886-A preliminary report: U.S. Geological Survey Professional Paper 1028, p. 43-57. 

Tarr, A. C., and Rhea, Susan, 1983, Seisnicity near 

Charleston, South Carolina, March 1973 to December 1979, in Gohn, G. S., ed., Studies related to the 

Charleston, South Carolina, earthquake of 1886-

Tectonics and seismicity: U.S. Geological Survey 

Professional Paper 1313R, p. R1-R17. 

Tarr, A. C., Talwani, Pradeep, Rhea, Susan, Carver, 

David, and Amick, David, 1981, Result~ of recent 

South Carolina Seismological studies: Seismological Society of America Bulletin, v. 71, I''). 6, 

p. 1883-1902. 

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bordering faults (abstract): Earthquake Notes, 

v. 55, no. 1, p. 2-3. 

48 
APPENDIX 

The Size of Earthquakes-Magnitude and Intensity 

To appreciate the enormous amount of energy released by the 1886 Charleston earthquake, it will be 

necessary to understand two different descriptions of 

earthquake size-magnitude and intensity. The former is proportional to the energy released as seismic 

waves (vibrations), and the latter measures the effects of these vibrations on nature and on man and 

his structures. Magnitude is quantitative; that is, it is 

based on objective measurements taken from seismograph recordings (seismograms) of the seismic 

waves. Intensity is qualitative and is based on subjective evaluations of the degree and the severity of 

the earthquake effects. 

Magnitude is the most widely known and used 

measure of earthquake size. The first proposed magnitude scale, called the local magnitude (Md scale, 

was developed by Professor C. F. Richter (1935). He 

called it local magnitude because it was designed 

specifically to measure the size of southern California earthquakes that were local or near to his institution, the California Institute of Technology. In the 

following decade, Richter and his colleague, Professor Beno Gutenberg, proposed other magnitude 

scales that could be used to estimate the strength of 

earthquakes at long distances from the seismograph 

stations. Two of these scales, the body wave (mb), 

and the surface wave (Ms). are still in common use. 

For any of the scales, local body wave, or surface 

wave, the formula used to calculate magnitude can 

be put in the form 

M =a + b log10 D + log10 (A/c) 

where 

M is unreferenced magnitude; that is, it can connote body wave, surface wave, or local; 

a is a term that attempts to account for the depth 

of the earthquake, the geology of the region 

being studied, the different seismic waves 

from which the measurements are to be 

made, the period of the waves, and other 

similar factors; 

b is the attenuation factor that accounts for the 

rate at which the seismic waves diminish in 

amplitude with increasing distance from the 

49 

epicenter. The value of b will vary w.th 

wave type, epicentral distance, and t'"-e geology of the region; 

log10 is the common logarithm to the base 10; that 

is, the power (or exponent) to which 10 must 

be raised to give the number for which the 

logarithm is desired; for exmaple, 

log10 10 = 1 because 101 = 10, 

log10 100 = 2 because 102 = 100, ar1 

log10 1,000 = 3 because 103 = 1,00C. 

It is this factor that is referred to by t':le 

news media when making statement~ such 

as "the magnitude is based on a seal~ of 

ten" and "a change of one unit in the magnitude (for example, from 4 to 5 or 7 to 8) 

corresponds to a tenfold increase in t"'le level 

of vibrations rr; 

D is the distance between the epicenter and the 

seismograph. Note that the term b lo:J10 D 

accounts for the decrease of seismic vibrational levels with increasing epicentral distance by becoming larger. If b = 1.6f,. then 

At D = 10 miles: 1.66 log10 10 = 

1.66 X 1 = 1.66, 

At D = 100 miles: 1.66 log10 100 = 

1.66 x 2 = 3.32, and 

At D = 1,000 miles: 1.66 log10 1,00<1 = 

1.66 X 3 = 4.98. 

Thus, increases in b log 10 D offset the 

natural decrease in the level of vibrational 

amplitudes (A, as defined below) and allow 

seismograph stations at near and far ranges 

to be used for calculating magnitude. Because of the presence of experimentd errors, the set of magnitude values for a given 

earthquake, each calculated from the amplitude at an individual station, are ave':'aged 

to arrive at a final magnitude value for that 

earthquake; 

A is the amplitude of the ground moticn of the 

wave used in determining the magnitude. 

The amplitude of the ground motion is obtained by dividing the amplitude on the 

seismogram by the magnification of the seismograph; 
cis a term sometimes used to account for the 

frequency or the period of the earthquake 

vibrations. Oftentimes, the effect of c is included in a, resulting in c = 1. 

Gutenberg and Richter attempted to select the a 

value in the equations above so that the numerical 

values of local magnitude, body-wave magnitude, 

and surface-wave magnitude would be the same for 

any earthquake. However, from theoretical considerations, it can be shown that this is not possible for all 

sizes of earthquakes. They chose the a values so that 

a California earthquake of ML = 6.5 would also have 

mb = 6.5 and Ms = 6.5. Later, they found that smaller 

California earthquakes have surface-wave-magnitude 

values that are numerically less than the body-wavemagnitude values and local-magnitude values and 

that larger California earthquakes have surfacewave-magnitude values that are numerically larger 

than the body-wave-magnitude and local-magnitude 

values. 

In the Eastern United States, the body-wavemagnitude and surface-wave-magnitude scales come 

together for earthquakes of mb = Ms = 5.7. Appendix 

figure 1 shows the relation between the body-wavemagnitude and surface-wave-magnitude scales for 

the Eastern United States (Nuttli, 1983). 

The term "Richter magnitude," frequently used by 

the news media, does not have a precise meaning. 

Oftentimes, it is taken to be the body-wave magnitude or local magnitude for small- to moderate-sized 

Ms 

Figure A-1. Relation between body-wave magnitude and surface-wave magnitude for 

earthquakes in the Eastern United 

States. (Adapted from Nuttli, 1983.) 

earthquakes and the surface-wave magnitude for 

large earthquakes. This mixing up of the magnitude 

scales can lead to trouble; for example, in determining recurrence rates of earthquakes of a particular 

magnitude or when estimating strong ground motion 

by scaled attenuation curves, with magiJ itude as the 

scaling parameter. 

In general, an earthquake of body-wave magnitude smaller than 2 to 2! will not be felt by people. 

Earthquakes of mb = 4! to 5 are widely felt in the 

Eastern United States. Usually, they will cause people to be alarmed but will not produce s·1bstantial 

damage. They may cause minor damage in the epicentral region, such as overturning or kr'lcking 

down unstable objects, cracking plaster, and breaking windows. An earthquake of mb = 5! to 6 

(Ms = 5.4-6.3) is considered a large eart1''1Uake in 

the Eastern United States. It will produo~ cracks in 

walls and crack or throw down chimney~ in the epicentral area. It will be felt strongly out to distances 

of hundreds of miles. Eastern earthquakes of mb = fi! 

and greater (Ms = 7.3 and greater) produce great destruction to buildings, as well as injury and possible 

loss of life. 

The intensity measure of earthquake size is qualitative and intended to specify the severity of the 

earthquake motion at a given point by its effect on 

people, structures, and the landscape at that point. It 

will be largest near the epicenter and will decrease 

with distance from that location. Thus, many different intensity numbers are assodated wit~ each 

shock. A typical application of intensity data is to 

plot each of the various values of the inV-:msities for a 

given earthquake at their appropraite locations on a 

map and then to contour these values. T'"' ~ resulting 

map is termed an "intensity" or "isoseismal" map. 

The intensity scale used in the United States is 

called the Modified Mercalli Intensity Scale (MM) 

and has 12 levels or degrees, ranging frcm I (felt 

only by a few people under especially favorable circumstances) to XII (total damage). By co:'lvention, roman numerals are used to denote intensity, and arabic numbers, for magnitude. Damage bf'!lins at 

about the intensity VI level. The followirg table contains a listing of the effects associated wl'th levels I to 

XII. It also contains the approximate ma~nitude 

range expected when those levels of int~"lsity are 

experienced near the epicenter. 

The determination of the intensity level to which a 

given location has been subjected consists of observing 

the effects of the earthquake shaking on p9ople, structures, and the landscape at that location and then 

matching that suite of effects with those given in the 

Modified Mercalli Intensity Scale. The mat"'h is seldom 

exact. Some effects listed in the scale may not have occurred, and others not listed in the scale (f 1r example, 

setting off of smoke alarms) may have taken place. 

Also, the observed effects may be split bet·,reen two 

different intensity levels on the scale. Conrequently 

these characteristics of intensity make the scale a subjective, qualitative measure of earthquake size. Consid50 
Modified Mercalli Intensity Scale 

Intensity 

II 

III 

IV 

v 

VI 

VII 

VIII 

IX 

X 

Description of effects 

Not felt except by a very few under especially favorable 

circumstances. 

(1-Rossi-Forel Scale.) 

Felt only by a few persons at rest, especially on upper floors of 

buildings. Delicately suspended objects may swing. 

(I to III-Rossi-Forel Scale.) 

Felt quite noticeably indoors, especially on upper floors of buildings, but many people do not recognize it as an earthquake. 

Standing motorcars may rock slightly. Vibration like passing 

truck. Duration estimated. 

(III-Rossi-Forel Scale.) 

During the day felt indoors by many, outdoors by few. At night 

some awakened. Dishes, windows, and doors disturbed; walls 

make creaking sound. Sensation like heavy truck striking building. Standing motorcars rocked noticeably. 

(IV to V-Rossi-Forel Scale.) 

Felt by nearly everyone; many awakened. Some dishes, windows, 

and so forth, broken; a few instances of cracked plaster; unstable 

objects overturned. Disturbance of trees, poles, and other tall objects sometimes noticed. Pendulum clocks may stop. 

(V to VI-Rossi-Forel Scale.) 

Felt by all; many frightened and run outdoors. Some heavy furniture moved; a few instances of fallen plaster or damaged chimneys. Damage slight. 

(VI to VII-Rossi-Forel Scale.) 

Everybody runs outdoors. Damage negligible in buildings of good 

design and construction; slight to moderate in well-built ordinary 

structures; considerable in poorly built or badly designed structures. Some chimneys broken. Noticed by persons driving 

automobiles. 

(VIII-Rossi-Forel Scale.) 

Damage slight in specially designed structures; considerable in ordinary substantial buildings, some partial collapse; great in 

poorly built structures. Panel walls thrown out of frame structures. Fall of chimneys, factory stacks, columns, monuments, 

walls. Heavy furniture overturned. Sand and mud ejected in 

small amounts. Change in well water. Persons driving automobiles disturbed. 

(VIII+ to IX-Rossi-Forel Scale.) 

General panic. Damage considerable in specially designed structures; well-designed frame structures thrown out of plumb; great 

in substantial buildings, some partial collapse. Ground cracked 

conspicuously. Underground pipes broken. 

(IX +-Rossi-Forel Scale.) 

Some well-built wooden structures destroyed; most masonry and 

frame structures destroyed with foundations; ground badly 

cracked. Rails bent. Landslides considerable from river banks 

and steep slopes. Shifted sand and mud. Water thrown over 

banks on canals, rivers, and so forth. Serious damage to dams, 

dikes, and embankments. 

(X-Rossi-Forel Scale.) 

51 

Magnitud~ 

2.0-2.4 

2.5-2.9 

3.0-3.5 

3.6-4.0 

4.1-4.4 3.0-3.3 

4.5-4.9 3.4-4.2 

5.0-5.5 4.3-5.3 

5.6-6.0 5.4-6.3 

6.1-6.5 6.4-7.3 

6.6-7.0 7.4-8.2 
Modified Mercalli Intensity Scale-Continued 

Magnitude 

Intensity Description of effects 

XI Few, if any, structures remain standing. Bridges destroyed. Broad 

fissures in ground. Underground pipelines completely out of service. Earth slumps and land slips in soft ground. Rails bent greatly. 

(X-Rossi-Forel Scale.) 

7.1-7.3 8.3-8.6 

XII Damage total. Waves seen on ground surfaces. Lines of sight and 

level distorted. Objects thrown upward into the air. 

(X-Rossi-Forel Scale.) 

7.4+ 8.7+ 

erable experience in the use of the scale by the observer is required to produce uniform results. One 

test has been reported (Bollinger, 1977) wherein 

three experienced seismologists independently evaluated about 1,300 different intensity reports. The result was that two or all three of the seismologists assigned the same intensity value for 90 percent of the 

reports. Most of the disagreement was at the lowest 

intensity levels where the differences in the scale are 

least pronounced. 

The qualitative nature of the intensity scale results 

from the multiplicity of factors that can influence its 

level at any given location. Among these factors are 

the following: 

Seismic Factors 

Magnitude 

Focal depth 

Focal mechanism (radiation pattern of the seismic 

waves) 

Partitioning of energy between wave types and 

periods 

Distance from the source 

Path effects (inhomogeneities between source and 

site) 

Geological Factors 

Character of bedrock geology 

Type and thickness of the soil layer 

Ground-water levels 

Slope and configuration of the ground surface 

Engineering Factors 

Type and quality of construction 

Size and configuration of the structure 

Interaction between nearby structures 

Human Factors 

Sensitivity of observer (previous expos'.tre, physical location) 

Location of observer (outdoors, indoors, type of 

building, floor of building) 

Time of day (observer sleeping or awake, active or 

quiet) 

Weather (storms, wind, and so forth, ccm mask effects) 

Sounds (can intensify fright) 

Currently, magnitude values and inten~ity maps 

are determined for each important earthruake. However, before the 1950's, too few instrume:'lts existed 

in the Eastern United States to provide d::tta for magnitude calculations. Thus, most of the his~orical data 

base consists of only intensity data. Modern data 

have been used, however, to infer magnitudes for 

the older shocks. Such was the case for t:'le 1886 

Charleston earthquake. Nuttli and others (1979) used 

the characteristics of the MM intensity m"lp to infer 

Ms = 7.7. By way of comparison, the famous 1906 

San Francisco, California, earthquake had Ms = 8.3. 

Yet another comparison would be with tr~ energy 

field of a nuclear explosion-the energy released by 

the 1886 earthquake would be roughly equivalent to 

that produced by the explosion of a 1-megaton 

bomb. 

U. S. GPO: 1588-201-985/93956 

52