Technical Investigation

of the May 22, 2011,

Tornado in Joplin, MO

December 10, 2013

NCST Advisory 

Committee Meeting

Emergency Communications, 

Public Response, and 

Tornado Deaths and Injuries

Erica D. Kuligowski

Joplin Task Leader

Engineering Laboratory, NIST
Objective #4

• Determine the pattern, location, and cause of 

fatalities and injuries, and associated emergency 

communications systems and public response 

Presentation Outline

1. Data Collection

2. Findings on casualties, emergency communications, and human response

– Context

– Emergency communications prior to May 22, 2011

– Tornado history prior to May 22, 2011

– Emergency communications on May 22, 2011

– Fatalities, Injuries and Public Response

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1. Data Collection

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Data Collected on Public Response 

and Emergency Communications

• 168 survivors (telephone/face-to-face interviews)

• Sample demographics

– Age: ranged from 18 to 88 (mean age = 51) 

– Gender: 59% women

– Authoritative role: 10%

– Information on the deceased: 10%

– Injured: 10%

– Geographic location: well distributed across the tornado path 

through Joplin, also in various types of buildings throughout the 

path (or outside of buildings)

• Over 100 media accounts of stories of survival

• Targeted interviews with and data collection from emergency 

response personnel (inside and outside City of Joplin, MO)

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• Death certificates obtained for all deaths from

– Missouri Department of Health and Senior Services

– Oklahoma State Department of Health

– Kansas Department of Health and Environment’s Office of Vital 

Statistics 

• Additional sources on deaths : NWS; MO State Police; Dr. 

Andrew Curtis; media accounts; NIST survivor interviews; 

social media; obituaries; American Red Cross

• Information on injuries obtained from:

– MO Department of Health and Senior Services

– CDC EPI-Aid Study (Source: MO Department of Health and 

Senior Services)

Data Collected on Fatalities/Injuries

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2. Findings Related to the Pattern, 

Location, and Cause of Fatalities and 

Injuries, and Associated Performance 

of Emergency Communications 

Systems and Public Response

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Findings (1) – Context

• F27: During the period from 1950 (i.e., the beginning of 

official tornado record keeping) through 2011, tornadoes 

caused approximately 5,600 fatalities in the United 

States. Within an 80–mile radius around Joplin, 233 

deaths (including those caused by the Joplin tornado) 

were caused by tornadoes during the same period.

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• F28: The Missouri State Police attributed 161 deaths and 

the City of Joplin attributed more than 1,000 injuries to the 

Joplin tornado, which affected an area with an estimated 

population of 20,820.

• F29: Of the 161 deaths resulting from this tornado: 

– 155 (96 percent) were caused by impact–related factors (i.e., 

multiple blunt force trauma to the body).

– Others were caused by stress–induced heart attacks, pneumonia, 

or lightning.

Findings (2) – Context and Fatalities 

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Map of the Location of 161 Fatalities

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© 2011 Geoeye. Used with Permission. 

Enhancements by NIST.
• F30/31: False alarm rates:

– There was evidence of high false–alarm rates among the storm– based tornado warnings officially issued for Joplin. 

– Despite public perception, no evidence was found of high false– alarm rates for Joplin’s outdoor siren system. 

Findings (3) – EC Prior to May 22, 2011 

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© OpenStreetMap contributors. 

Enhancements by NIST.
• F32: Joplin residents interviewed after the Joplin tornado 

believed that there had been a high number of false 

alarms in Joplin from official tornado warnings and the 

City’s outdoor siren system prior to 2011, even though 

the siren activation rate was once per year (on average).

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Findings (4) – EC Prior to May 22, 2011 
• F33: Prior to 2011, the roughly 30–square–mile City of 

Joplin had experienced one tornado rated EF–2 or greater 

since 1950; this tornado occurred on May 5, 1971. 

However, also since 1950, 182 tornadoes rated EF–2 or 

higher had struck within an 80–mile radius of the City.

Findings (5) – Tornado History Prior to 

May 22, 2011

12

© C.F. Boone Publications.

Used with permission.
• F34: Prior to the May 22, 2011, Joplin tornado, 

scientifically unfounded beliefs about tornado 

movements and the effects of regional topography 

contributed to a common public perception that the City 

of Joplin was immune to a direct tornado strike.

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Findings (6) – Tornado History Prior to 

May 22, 2011
• F35: Two official tornado warnings were issued on May 

22, 2011. 

– After the first official warning, Joplin’s sirens were sounded but no 

tornado occurred. 

– After the second official warning, the siren system was sounded 

again, 4 minutes after the tornado touched down and almost exactly 

when the tornado entered the City of Joplin. 

– Both siren soundings took the form of a continuous tone of 3 minutes 

duration.

• F36: Joplin’s outdoor siren system, which could generally 

be heard indoors as well as outside, was the primary 

means by which individuals were alerted to a tornado 

event on May 22, 2011. Radio, television, and word of 

mouth were the primary means by which individuals were 

provided with warning information on May 22, 2011. 

Findings (7) – Emergency 

Communications on May 22, 2011

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• F37: The Joplin–Jasper County Reverse–9–1–1 

telephone system was not used on May 22, 2011, due to 

its inability to disseminate information in a timely manner. 

• F38: Functioning as an alerting system, only, the outdoor 

sirens prompted many Joplin residents and visitors to 

seek further information on May 22, 2011. The multiplicity 

of information sources, and the conflicting information 

provided by those sources, added to the public’s 

confusion about the true hazard as additional information 

was sought.

Findings (8) – Emergency 

Communications on May 22, 2011, cont.

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• F39: Across the country, there is no 

standard method for sounding outdoor 

public siren systems, which has led to 

variations in siren usage, activation 

procedures, and sounding patterns 

among U.S. communities. Also, there 

are no nationally accepted standard 

protocols for the issuance of an all–

clear alert following a warning.

Findings (9) – Emergency 

Communications on May 22, 2011, cont.

16

© 2011 Federal Signal. 

Used with permission.
• F40: Of the 155 impact–related fatalities:

– 135 (87 percent) involved persons who are known to have been 

located inside structures during the tornado. 

– The structures in which these people died included both 

residential (59 percent of the 135 victims) and non–residential (41 

percent) buildings. 

• F41: Virtually all of the buildings in which the 135 impact–

related fatalities occurred experienced maximum 

estimated winds associated with tornadoes rated EF–3 or 

higher. Exceptions (EF2 or lower): 

– Meadows Healthcare facility, where two of the deaths occurred,

– Five single–family homes that were the sites of six of the fatalities.

Findings (10) – Fatalities and Injuries

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Findings (11) – Fatalities and Injuries

• F42: The hospital towers at SJRMC did not provide life– safety protection for all occupants, even though the 

towers did not collapse. Twelve impact–related fatalities 

occurred in the hospital, four of which involved patients 

in intensive care units.

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Findings (12) – Public Response, cont.

• F43: Responses to the 

approaching tornado 

among members of the 

public, in many cases, 

were delayed or 

incomplete

• F44: Two factors were 

found to have 

contributed:

– Lack of awareness

– Inability to perceive 

personal risk

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• F45: The main factor that convinced individuals to take 

shelter was the receipt of high–intensity cues, including 

hearing or seeing the tornado approaching or witnessing 

others’ urgency related to taking protection.

• F46: No fatalities occurred in demolished, detached 

homes in which people took refuge in basements. 

Additionally, NIST found no evidence that any of those 

killed were located underground during the tornado.

Findings (13) – Public Response, cont.

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• F47: A disproportionate number of people aged 60 years 

or older died or were injured as a result of this tornado. 

NIST analysis of the fatalities resulting from the Joplin 

tornado shows that approximately 8 fatalities occurred per 

thousand people in Joplin aged 60 years and over 

compared with 2 fatalities per thousand people in Joplin 

under 60 years. 

Findings (14) – Public Response, cont.

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0 to 9 10 to 19 20 to 29 30 to 39 40 to 49 50 to 59 60 to 69 70 to 79 80+

Fatalities per Thousand People (within 

the Population)

Age Range

Tornado Fatality Rates by 10–Year Age Range (154 

Fatalities)

Tornado Fatality Rates (Joplin Population)

Tornado Fatality rates (Census Track

population)

Residential Tornado Fatality rates (Census

Track population)