Jul 092017

Earthquakes strike suddenly, violently, and without warning. While Colorado is not as seismically active as some places, it does have a history of earthquake activity. Identifying potential hazards ahead of time and advance planning can reduce the dangers of serious injury or loss of life from an earthquake. Repairing deep plaster cracks in ceilings and foundations, anchoring overhead lighting fixtures to the ceiling, and following local seismic building standards, will help reduce the impact of earthquakes.

Six Ways to Plan Ahead

1.) Check for Hazards in the Home
  • Fasten shelves securely to walls.
  • Place large or heavy objects on lower shelves.
  • Store breakable items such as bottled foods, glass, and china in low, closed cabinets with latches.
  • Hang heavy items such as pictures and mirrors away from beds, couches, and anywhere people sit.
  • Brace overhead light fixtures.
  • Repair defective electrical wiring and leaky gas connections. These are potential fire risks.
  • Secure a water heater by strapping it to the wall studs and bolting it to the floor.
  • Repair any deep cracks in ceilings or foundations. Get expert advice if there are signs of structural defects.
  • Store weed killers, pesticides, and flammable products securely in closed cabinets with latches and on bottom shelves.
2.) Identify Safe Places Indoors and Outdoors
  • Under sturdy furniture such as a heavy desk or table.
  • Against an inside wall.
  • Away from where glass could shatter around windows, mirrors, pictures, or where heavy bookcases or other heavy furniture could fall over.
  • In the open, away from buildings, trees, telephone and electrical lines, overpasses, or elevated expressways.
3.) Educate Yourself and Family Members
  • Contact your local emergency management office or American Red Cross chapter for more information on earthquakes. Also read the “How-To Series” for information on how to protect your property from earthquakes.
  • Teach children how and when to call 9-1-1, police, or fire department and which radio station to tune to for emergency information.
  • Teach all family members how and when to turn off gas, electricity, and water.
4.) Have Disaster Supplies on Hand
  • Flashlight and extra batteries.
  • Portable battery-operated radio and extra batteries.
  • First aid kit and manual.
  • Emergency food and water.
  • Nonelectric can opener.
  • Essential medicines.
  • Cash and credit cards.
  • Sturdy shoes.
5.) Develop an Emergency Communications Plan
  • In case family members are separated from one another during an earthquake (a real possibility during the day when adults are at work and children are at school), develop a plan for reuniting after the disaster.
  • Ask an out-of-state relative or friend to serve as the “family contact.” After a disaster, it’s often easier to call long distance. Make sure everyone in the family knows the name, address, and phone number of the contact person.
6.) Help Your Community Get Ready
  • Publish a special section in your local newspaper with emergency information on earthquakes. Localize the information by printing the phone numbers of local emergency services offices, the American Red Cross, and hospitals.
  • Conduct a week-long series on locating hazards in the home.
  • Work with local emergency services and American Red Cross officials to prepare special reports for people with mobility impairments on what to do during an earthquake.
  • Provide tips on conducting earthquake drills in the home.
  • Interview representatives of the gas, electric, and water companies about shutting off utilities.
  • Work together in your community to apply your knowledge to building codes, retrofitting programs, hazard hunts, and neighborhood and family emergency plans.

What To Do During an Earthquake

Stay as safe as possible during an earthquake. Be aware that some earthquakes are actually foreshocks and a larger earthquake might occur. Minimize your movements to a few steps to a nearby safe place and stay indoors until the shaking has stopped and you are sure exiting is safe.

If indoors
  • DROP to the ground; take COVER by getting under a sturdy table or other piece of furniture; and HOLD ON until the shaking stops. If there isn’t a table or desk near you, cover your face and head with your arms and crouch in an inside corner of the building.
  • Stay away from glass, windows, outside doors and walls, and anything that could fall, such as lighting fixtures or furniture.
  • Stay in bed if you are there when the earthquake strikes. Hold on and protect your head with a pillow, unless you are under a heavy light fixture that could fall. In that case, move to the nearest safe place.
  • Use a doorway for shelter only if it is in close proximity to you and if you know it is a strongly supported, load-bearing doorway.
  • Stay inside until shaking stops and it is safe to go outside. Research has shown that most injuries occur when people inside buildings attempt to move to a different location inside the building or try to leave.
  • Be aware that the electricity may go out or the sprinkler systems or fire alarms may turn on.
  • DO NOT use the elevators.
If outdoors
  • Stay there.
  • Move away from buildings, streetlights, and utility wires.
  • Once in the open, stay there until the shaking stops. The greatest danger exists directly outside buildings, at exits, and alongside exterior walls. Many of the 120 fatalities from the 1933 Long Beach, California earthquake occurred when people ran outside of buildings only to be killed by falling debris from collapsing walls. Ground movement during an earthquake is seldom the direct cause of death or injury. Most earthquake-related casualties result from collapsing walls, flying glass, and falling objects.
If in a moving vehicle
  • Stop as quickly as safety permits and stay in the vehicle. Avoid stopping near or under buildings, trees, overpasses, and utility wires.
  • Proceed cautiously once the earthquake has stopped. Avoid roads, bridges, or ramps that might have been damaged by the earthquake
If trapped under debris
  • Do not light a match.
  • Do not move about or kick up dust.
  • Cover your mouth with a handkerchief or clothing.
  • Tap on a pipe or wall so rescuers can locate you. Use a whistle if one is available. Shout only as a last resort. Shouting can cause you to inhale dangerous amounts of dust.

What To Do After an Earthquake

  • Expect aftershocks. These secondary shockwaves are usually less violent than the main quake but can be strong enough to do additional damage to weakened structures and can occur in the first hours, days, weeks, or even months after the quake.
  • Listen to a battery-operated radio or television. Listen for the latest emergency information.
  • Use the telephone only for emergency calls.
  • Open cabinets cautiously. Beware of objects that can fall off shelves.
  • Stay away from damaged areas. Stay away unless your assistance has been specifically requested by police, fire, or relief organizations. Return home only when authorities say it is safe.
  • Be aware of possible tsunamis if you live in coastal areas. These are also known as seismic sea waves (mistakenly called “tidal waves”). When local authorities issue a tsunami warning, assume that a series of dangerous waves is on the way. Stay away from the beach.
  • Help injured or trapped persons. Remember to help your neighbors who may require special assistance such as infants, the elderly, and people with disabilities. Give first aid where appropriate. Do not move seriously injured persons unless they are in immediate danger of further injury. Call for help.
  • Clean up spilled medicines, bleaches, gasoline or other flammable liquids immediately. Leave the area if you smell gas or fumes from other chemicals.
  • Inspect the entire length of chimneys for damage. Unnoticed damage could lead to a fire.
  • Inspect utilities.
  • Check for gas leaks. If you smell gas or hear blowing or hissing noise, open a window and quickly leave the building. Turn off the gas at the outside main valve if you can and call the gas company from a neighbor’s home. If you turn off the gas for any reason, it must be turned back on by a professional.
  • Look for electrical system damage. If you see sparks or broken or frayed wires, or if you smell hot insulation, turn off the electricity at the main fuse box or circuit breaker. If you have to step in water to get to the fuse box or circuit breaker, call an electrician first for advice.
  • Check for sewage and water lines damage. If you suspect sewage lines are damaged, avoid using the toilets and call a plumber. If water pipes are damaged, contact the water company and avoid using water from the tap. You can obtain safe water by melting ice cubes.

Refer to Federal Emergency Management Agency‘s earthquake preparedness web site for further information.

Jul 032017

Nearly 100 potentially hazardous faults have been identified in Colorado. Generally, these are faults thought to have had movement within about the past 2 million years. There are other faults in the state that may have potential for producing future earthquakes. Because the occurrence of earthquakes is relatively infrequent in Colorado and the historical earthquake record is relatively short (only about 130 years), it is not possible to accurately estimate the timing or location of future dangerous earthquakes in Colorado. Nevertheless, the available seismic hazard information can provide a basis for a reasoned and prudent approach to seismic safety.


Sudden movement on long faults is responsible for large earthquakes. By studying the geologic characteristics of faults, geoscientists can often determine when the fault last moved and estimate the magnitude of the earthquake that produced the last movement. In some cases it is possible to evaluate how frequently large earthquakes occurred on a specific fault during the recent geological past.

Geological studies in Colorado have discovered about 100 faults that moved during the Quaternary Period (past 2 million years) and could be considered potentially active. The Sangre de Cristo fault, which lies at the base of the Sangre de Cristo Mountains along the eastern edge of the San Luis Valley, and the Sawatch fault, which runs along the eastern margin of the Sawatch Range, are two prominent and potentially active faults in Colorado. However, not all of Colorado’s potentially active faults are in the mountains. For example, the Cheraw fault, which is in the Great Plains Physiographic Province in southeast Colorado, appears to have had multiple movements during the recent geologic past. Some potentially active faults cannot be seen at the earth’s surface. The Derby fault near Commerce City lies thousands of feet below the earth’s surface. It has not been recognized at ground level, and for that reason it is not included on the CGS Earthquake and Late Cenezoic Fault and Fold Map Server [1].

Screen-shot from the Earthquake and Late Cenezoic Fault and Fold Map Server.

Screen-shot from the Earthquake and Late Cenezoic Fault and Fold Map Server.

Several potentially active faults in Colorado are thought to be capable of causing earthquakes as large as magnitude 7.2 based on recent detailed studies. In comparison, California has hundreds of hazardous faults, one or two of which can cause earthquakes of magnitude 8.0 or larger. The time interval between large earthquakes on faults in Colorado is generally much longer than on faults in California.

Past and Possible Future Earthquakes

About 400 earthquake tremors of magnitude 2.5 or higher have been reported in Colorado since 1867. More earthquakes of magnitude 2.5 to 3.0 probably occurred during that time, but were not recorded because of the sparse distribution of population and limited instrumental coverage in much of the state. The largest known historical earthquake in Colorado occurred on November 7, 1882 and had an estimated magnitude of 6.6. The location of this earthquake probably was in the northern Front Range.

Although many of Colorado’s earthquakes occurred in mountainous regions of the state, some have been located in the western valley and plateau region or east of the mountains. The best known Colorado earthquakes were a series of events in the 1960s that were later shown to be triggered by the injection of liquid waste into a deep borehole at the Rocky Mountain Arsenal. Twelve of the so-called “Arsenal” earthquakes caused damage, including a magnitude 5.3 earthquake on August 9, 1967 that resulted in more than a million dollars in damage in Denver and the northern suburbs. This series of earthquakes continued for about ten years and was followed by about six years of quiescence. Earthquake activity resumed in the northeast Denver area in 1978, including a magnitude 4.3 event on April 2, 1981.

Colorado’s earthquake hazard is similar to other states in the intermountain west region. It is less than in states like California, Nevada, Washington, and Oregon, but greater than many states in the central and eastern United States. It is prudent to expect future earthquakes as large as magnitude 6.6, the largest historical event in Colorado.

Conclusions and Recommendations

Based on Colorado’s historical earthquake record and geologic studies, an event as large as magnitude 6.5 to 7.2 could occur somewhere in the state. Scientists are unable to accurately predict when the next major earthquake will take place in Colorado; only that one will occur. The major factors that prevent the prediction of the timing and location of future damaging earthquakes are the limited knowledge of potentially active faults and short historical record of earthquakes. Given Colorado’s continuing active economic growth and the accompanying expansion of population and infrastructure, it is prudent to continue the study and analysis of earthquake hazards. Existing knowledge should be used to incorporate appropriate levels of seismic safety into building codes and practices. Seismic safety of critical facilities and vulnerable structures is especially important. Emergency response and recovery planning should consider earthquake hazards and risk. Concurrently, we should expand earthquake monitoring, geological and geophysical research, and mitigation planning and activities.


[1] Kirkham, R. M., W. P. Rogers, L. Powell, M. L. Morgan, V. Matthews, and G. R. Pattyn. “Bulletin 52B – Earthquake and Late Cenezoic Fault and Fold Map Server.” Earthquake. Bulletin. Denver, CO: Colorado Geological Survey, Department of Natural Resources, 2004.

May 032017

The CGS recently installed the first of five new seismic recording stations that will collect information on seismic events around the state and the region. The CGS seismic network acts in conjunction with those maintained by the University of Colorado and Colorado State University, the Incorporated Research Institutions for Seismology (IRIS), and the US Geological Survey‘s National Earthquake Information Center (NEIC) — to provide near real-time earthquake detection. The addition of our monitoring capacity, the wider network allows the geoscience research community to better understand background seismicity in Colorado and better discriminate between natural and induced seismic events that may occur in the region.

The CGS already operates four other stations with Streckeisen STS-2 Broadband Sensors (capable of sensing ground motions over the frequency band 0.01 Hz (100 sec) to 15 Hz). They were part of a national consortium — USARRAY — that was a portable seismic network migrating around to different locations in the US several years ago. State-level organizations were allowed to ‘adopt’ some of the stations that were deployed within each state. The CGS purchased the four stations in 2010 — they are included on the map below as red boxes.

The set-up for a typical recording station includes the seismometer and its associated data recorder, a power system, and a communications system. The install site is carefully chosen for its relative acoustic silence — such that human-caused (road and air-traffic) and natural (wind, animal) noise levels are minimal at the relevant frequencies. The CGS cooperates with the Colorado State Land Board and the Colorado State Parks system in locating optimal sites for the stations in the CGS network. The particular station illustrated here is our Briggsdale Seismic Station #T25A-1 near Greeley, Colorado.

The physical installation of an isolated off-grid seismometer station includes the excavation of a pit for the seismometer ‘vault’ to sit in, a trench for cabling from the seismometer to the recording and power equipment, and a photo-voltaic (solar) power and data transmission tower. Adequate fencing to isolate the installation from noise and physical disturbance — in this particular case, grazing cattle — is important.

Images from the installation of our fifth seismometer station near Briggsdale, Colorado.

A seismometer is a device that can sense a wide range of ground motions or vibrations. Environmental considerations require that its underground installation be both level and thermally insulated. A sub-surface concrete pad is prepared with a glass plate embedded on the top to provide a perfectly flat platform for the seismometer to sit on. After precise leveling, the seismometer is then connected to a data recording system that is installed some distance away in a weather-proof console — again to keep possible vibrations from the tower at a minimum. The data recording box includes an A-to-D (Analog-to-Digital) converter that digitizes the signal and prepares it for transmission via the communications system.

The communications system consists of a modem and a GPS transceiver. Once recorded by the seismometer, a seismic trace is converted to a digital signal, processed and sent via the modem to a local cell tower where it is relayed first to IRIS and then on to the NEIC for correlation and display. The GPS provides a standard clock signal for data synchronization, an important factor in coordinating each individual seismic station with the wider network of stations. The IRIS website provides current near-real-time data for the Briggsdale station as well as all other stations in the network.

The power system includes a deep-cycle marine battery, and a photovoltaic panel for recharging along with a voltage inverter/charge controller to ensure a stable power supply for the data recording and communications system.

The map includes our seismic stations (totaling five as of 2017) along with others available across Colorado:

Feb 282017

We have a free 8.5- x 11-inch (pdf) geologic map of Colorado containing Geo-Whizology of Colorado on the reverse side.

Free 8.5- x 11-inch  map of Colorado geology along with Geo-Whizology

Free 8.5- x 11-inch map of Colorado geology (front) along with Geo-Whizology (back)

Of course, we’re a bit biased, but we think Colorado has magnificent geology and it is beautifully displayed for all to see. The state holds many of the biggest, the best, the first, and the most diverse:

For instance, did you know: Continue reading »