7.0 Magnitude Earthquake Rocks Anchorage, Alaska

The morning of November 30th, 2018, at 8:29 AM local time, a 7.0 magnitude earthquake shook the city of Anchorage, Alaska. The origin of the quake was 7 miles north of the city, resulting in the residents of Anchorage feeling the full intensity of this earthquake. Luckily, the epicenter was at a depth of 27 miles into the Earth’s crust. The depth of the origin allowed for the seismic energy of the earthquake to diminish slightly while making the 27-mile vertical journey before wreaking havoc on the surface.

The Shake Map shows the extent and magnitude in the surrounding areas during the 7.0 earthquake near Anchorage, Alaska,.

The Shake Map shows the extent and magnitude in the surrounding areas during the 7.0 earthquake near Anchorage, Alaska,.

Upon reaching the surface, the resulting damages included widespread power outages, severe damage to roadways and other transportation infrastructure, and internal damage to residential and commercial structures. Immediately after the quake hit, the USGS released figures that contained frightening numbers depicting the probability of economic losses. The figure below shows that, according to the USGS predicted losses, there is a 35 percent chance of damages ranging from $100 million – $1 billion. The data goes on to show that there is a 20 percent chance that the economic losses could very well total over one billion dollars!

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Immediately after the quake and ongoing through this week, the area continues to be inundated with relentless aftershocks that still hold immense power. As of this morning, the area has been the recipient of over 2,700 aftershocks and tremors, ranging in magnitude from 1 up to 5. There is still potential for an aftershock to be nearly as powerful as the original incident itself, which would cause even more damage during the recovery process.

Looking Back

In 1964, Anchorage fell victim to a 9.2 magnitude quake that caused damage to such an extent that certain parts of the city were unrecognizable. This earthquake killed 15 people during the event and another 124 from the resultant tsunami. Only one earthquake in recorded history has been more powerful (9.5 magnitude in Chile 1960). In the wake of this devastating event, the changes to the building codes may have resulted in massive economic saves in relation to building loss during this most recent quake. One of the key ideas that resulted from the research in the aftermath of the 9.2 magnitude event was the concept of integrating ductility into modern architecture and design. Ductility is the ability to bend without breaking, which helps absorb some of the seismic motion during an earthquake. One way this could be achieved in the case of concrete structures would be ensuring the right amount of steel reinforcement is located in the correct areas of the structure. This is just one example of the engineering constructs resulting from the Earthquake Hazard Reduction Act of 1977, which was sparked by the enormous 1964 earthquake.

Sources:

https://www.adn.com/alaska-news/2018/12/06/2788-and-counting-when-do-tremors-stop-being-aftershocks-and-start-being-new-earthquakes/

https://www.curbed.com/2018/12/3/18124154/alaska-earthquake-anchorage-building-codes

https://earthquake.alaska.edu/anchorage-m70-what-we-know-so-far

https://www.pe.com/2014/04/07/earthquakes-alaska-disaster-jolted-nation-into-making-changes/

Thomas Fire

Take Aways from the Discussion On “The Thomas Fire Retrospective Report”

RedZone Senior Wildfire Liaison Doug Lannon attended The Thomas Fire Retrospective Report discussion was held at 5:30 pm on Wednesday, October 17th, 2018 at the Montecito Fire Protection District (FPD) Headquarters located at 595 San Ysidro Road in the community of Montecito, California. These are some key points that Doug took away from the discussion.

The presentation was sponsored by the Montecito FPD Board of Directors and Montecito Fire Chief Chip Hickman. The discussion was led and facilitated by Dr. Crystal Kolden, Director of the Pyrogeography Lab and Associate Professor of Fire Science for the University of Idaho, College of Natural Resources. Dr. Kolden presented the history of the community of Montecito’s Wildland Fire Program Policy, and actions from when it was first discussed after the devastating Painted Cave Fire which occurred in 1990 near Goleta, and was then instituted after the even more destructive Tunnel Fire which occurred in 1991 in the Oakland Hills. The program has been enthusiastically supported and continued to date by the Montecito FPD Board of Directors, the Montecito FPD personnel, and the Citizens of Montecito, due to a highly effective and efficient Community Fire Protection and Fire Prevention Education and Partnership Program. Dr. Kolden also discussed the types of mitigation strategies that have been successful in recent wildfires, both for individual homeowners and for communities.

Thomas Fire Progression

The map above shows the new acreage that was burned at the end of each day.

Montecito was just one of several cities and communities that were threatened and received significant impact to residential and commercial properties during the 2017 Thomas Fire. However, compared to other communities impacted by the Thomas Fire, the community of Montecito suffered only a fraction of the damage that other communities suffered during the Thomas Fire. Montecito’s wildland fire program has spent the last 20 years developing a set of systems to combat the threat of wildfire. These systems include implementing new stringent building codes and architectural guidelines, creating a hazardous fuel treatment network across the northern portion of the community, developing a pre-attack plan to disseminate critical fire ground information to mutual aid resources, developing partnerships within the community and with adjacent agencies, and building a community education program that facilitates a positive working relationship with the community. These systems were successfully deployed to support structure defense actions by the more than 500 firefighters assigned to Montecito the morning of December 16th, 2017. The Community Education and Partnership Program include: defensible space surveys and inspections, neighborhood chipping days, preparedness planning, pre-attack zones and homes, voluntary and mandatory evacuation zones and trigger points, widening roads, hardening structures, and ornamental shrubbery around structures, etc. In part, due to the effectiveness of the systems, only minimal structure loss and damage occurred, but most importantly, no lives were lost or serious injuries occurred prior to and during the fire fight. A post-fire assessment found that the seven primary residences destroyed during the Thomas Fire lacked defensible space, lacked safe access due to narrow roads or no turnarounds for fire apparatus, were constructed of flammable construction materials, or were situated where gaps existed in the fuel treatment network. Forty other properties received varying degrees of damage to outbuildings, fencing, ornamental shrubbery, etc.

Fuel break in heavy timber

Depicted in the image above is a well defined fuel break similar to the examples mentioned in this blog topics.

In retrospect, the Thomas Fire demonstrated how proactive actions implemented by the District and the community in the past 20 years contributed to the successful defense of the community during the Thomas Fire. Post-fire, Montecito still has unburned fuel in smaller enclaves within the community and within the 2008 Tea Fire and 2009 Jesusita Fire burn scars. These open space areas still have the potential to support smaller, more localized wildfires. Given the favorable climatic conditions of the Central Coast, over the next 10-20 years, vegetation in the footprint of the Thomas Fire will be able to support wildfire again. There is much opportunity for the District to use the Thomas Fire burned area to continue to expand and improve upon the existing fuel treatment network. Treating vegetation as it regrows will be less labor intensive and less costly than in the past. Leveraging community partnerships, improving the use of technology to support fire operations, modifying defensible space fire codes, and continuing the wildland fire safety and education of the community are critical steps for the District in the upcoming years as they prepare for the inevitable next wildfire. We know it’s coming, it’s just a matter of when!

(Excerpts for this story were taken from the Thomas Fire Retrospective Report produced by GEO Elements, LLC.)

Structural damage from the Magnitude 8.8 earthquake in Chile in 2016 (Source: Expansion - CNN)

What is the difference between an earthquake’s magnitude and intensity?

Think about sitting around a campfire. The fire emits a measurable level of heat, and the nearer you sit to it, the hotter the fire feels. If you are farther from the fire, the heat is less intense. This simple example can explain common earthquake measurements – magnitude and intensity – and what these earthquake scales mean.

Richter Scale

Consider, once again, the campfire. This temperature is measurable and absolute. When an earthquake occurs, the Richter scale measures the magnitude of the earthquake at its epicenter. The Richter scale was developed in 1935 as a way to quantify the strength of earthquakes. It is a logarithmic scale based on the amplitude of the waves recorded by seismographs. A logarithmic scale means a magnitude increase of 1 relates to an energy increase by a factor of 10. An earthquake measuring a 4.0 on the Richter scale is 10 times as strong as a 3.0!

Seismograph at Weston Observatory at Boston College, Weston, Massachusetts

Earthquake seismograph at Weston Observatory at Boston College, Weston, Massachusetts.

 

Modified Mercali Intensity Scale

Now, you know the closer to the campfire you sit, the hotter the flames feel on your skin. This generally holds true with earthquakes as well. Typically, the nearer the epicenter the stronger the ground shaking you would feel; however, there are other factors that affect the intensity of the earthquake you feel at your location. The type of earthquake, bedrock the shockwaves traveled through, and amplitude of the shockwaves from the earthquake are a few of these factors. The intensity you feel is measured on a scale called the Modified Mercali Intensity Scale (MMI). The MMI scale ranges from “Not Felt” and “Weak Shaking” up to “Violent” and “Extreme” with well-built structures suffering damage.

USGS map and intensity scale for 1971 San Fernando Earthquake (Magnitude - red-circled, epicenter - star, intensity - table)

USGS earthquake map and intensity scale for 1971 San Fernando Earthquake (Magnitude – red-circled, epicenter – star, Modified Mercali Intensity scale – table)

Other Scales Around the World

While the Richter scale is widely known and the MMI scale is used in the United States, there are other magnitude and intensity scales in use around the world. The Japanese Meteorological Agency uses a separate calculation for shallow earthquakes (depth < 60km) which has been shown to be reasonable when the magnitude is 4.5-7.5; however, this magnitude measurement has historically underestimated larger magnitude tremors. Additionally, Japan and Taiwan use the Shindo intensity scale which has significant correlation to the MMI scale. During the middle to late 20th century, the USSR, East Germany, and Czecholsovakia established and utilized the Medvedev-Sponheuer-Karnik scale (MSK) to evaluate shaking and effects from earthquakes. This scale was built upon in the 1990s by the European Seismological Commission as they shifted to implement the European Macroseismic Scale for European countries. The MSK scale continues to be employed in Russia, India, Israel, and the Commonwealth of Independent States.

You can read more about some of these other scales here:

JMA Shindo intensity scale: https://www.jma.go.jp/jma/en/Activities/inttable.html

MSK Scale: https://www.gktoday.in/gk/various-earthquake-scales/

 

Sources:

https://earthquake.usgs.gov/learn/topics/mercalli.php

https://www.japan-talk.com/jt/new/why-japan-doesnt-use-magnitude-for-earthquakes

How Tsunami Early Warning Systems Work, and Why Indonesia’s System Failed.

Tsunamis are a scary and devastating natural phenomenon. On average, two damaging tsunamis occur globally each year. A major, devastating, ocean-wide tsunami occurs roughly every 15 years. To prevent catastrophic loss of life, many countries have independently or jointly developed tsunami early warning systems. Indonesia was hit with a massive earthquake and subsequent tsunami last month, and their warning system failed. To understand how these systems work and how they can fail, it is important to understand the causes of tsunamis. At the most basic, a tsunami is caused by a large, sudden motion on the seafloor. Earthquakes beneath or near the ocean most commonly cause this motion, but other potential causes include volcanic eruptions, underwater landslides, or even an above water landslide, such as a large piece of ice breaking off an iceberg or a meteor striking the ocean.

How Tsunami Early Warning Systems Work

Since a vast majority of tsunamis are caused by seismic activity on the seafloor, warning systems start with seismic monitoring. Sensors on the seafloor monitor for seismic activity caused by earthquakes and volcanoes. If a substantial seismic incident occurs, surface buoy sensors then monitor for changes in the sea level. Tsunami waves could be as shallow as three feet high, so these sensors are placed in an array to determine motion as well as height. These seafloor and surface buoy sensors send data to tsunami warning centers, which are staffed 24/7. The centers monitor the data, perform analysis, and quickly determine whether conditions are met to issue a tsunami warning alert. If an alert is sent, it goes to local radio and television, wireless emergency alerts, NOAA Weather Radio, and NOAA websites. Some tsunami threat areas might also issue warnings through sirens, text message alerts, and phone notifications.

 

NOAA’s Deep-ocean Assessment and Reporting of Tsunami System (NOAA)

 

What Failed in Indonesia?

On September 28, 2018, a 7.5 magnitude earthquake hit Sulawesi, Indonesia. A tsunami alert was briefly issued cautioning a possible tsunami of 0.5 meters, before a tsunami struck the city of Palu. The tsunami that hit was later estimated to be closer to 5 or 6 meters, causing widespread destruction and leading to over 7,000 people confirmed dead or never found. Another 10,000 people were reported injured.

“Indonesia built a network of buoys for detecting tsunamis, but due to lack of maintenance, the system is no longer operational”

Following the tsunami, officials in Indonesia faced heavy criticism for failing to warn the people of the severity of the incident, and several investigations were conducted into what failed within the system. As is common with system failures of this magnitude, several factors combined to bring about the failure.

Detection: Indonesia built a network of buoys for detecting tsunamis, but due to lack of maintenance, the system is no longer operational. Their closest tidal gauge was 125 miles away from Palu, and only recorded a 2.3 inch rise in water level. These tidal gauges are not primarily intended to detect tsunamis, since their sample rate is only every 15 minutes. Seismometers alone proved inadequate to predict the severity of the tsunami.

Warning: Cell phone towers in the area had already been damaged and were inoperable due to the earthquake that preempted the tsunami and many areas did not receive cell phone alerts. Palu was seen as a fairly protected city due to its deep bay and surrounding mountains. Due to this perceived natural protection, the beach regions were not equipped with warning sirens. The geography of this bay likely contributed to the severity of the tsunami instead of protecting the bay by funneling the water to a concentrated point, similar to how a narrowing river speeds up the flow.

Due to the limitations of the detection and warning systems in Indonesia, officials are stressing educating the public that any earthquake lasting longer than 20 seconds is a tsunami threat. If an earthquake occurs, they recommend getting to higher ground immediately and not waiting for a warning.

 

Sources:

https://www.tsunami.gov/

https://www.usgs.gov/faqs/what-are-tsunamis?qt-news_science_products=0#qt-news_science_products

https://www.noaa.gov/explainers/us-tsunami-warning-system

https://www.nytimes.com/interactive/2018/10/02/world/asia/indonesia-tsunami-early-warning-system.html

Mendocino Complex Fire Progression Map

The Mendocino Complex: An Update on Current Conditions

Mendocino Complex Fire Summary

The Ranch fire, which is being managed as a part of the Mendocino Complex, Started on July 27th on the north bound side of highway 20, east of Lake Mendocino. Fuels in this area consisted of grass, brush and Oak trees. The grasses along the highway led the fire rapidly becoming established and making a run upslope to the east. Due to winds in the area the first resources on scene were not able to catch this fire in its initial stages.

The Second fire being managed under the Mendocino Complex is the River Fire. The River Fire began on the east side of Old River Road, nearly 7 miles southeast of Ukiah, CA. Similar to the Ranch fire, the River Fire began in grasses and became rapidly established making a run up slope to the Southeast. The two incidents spread in a very similar manner for the first 3 days due to both fires burning in identical fuel types, and experiencing the same wind conditions during the initial attack phase. This is depicted very well in the fire progression map provided by the incident management team below.

Mendocino Complex Fire Progression Map

Fire progression map displaying the similarities in burn patterns for the initial 3-4 day period of these campaign fires.

Mendocino Complex as of August 16, 2018

The type-1 incident management team has been making significant progress with suppression efforts on these two fires. Currently the River fire remains with 48,920 acres burn and is 100 percent contained. The Ranch Fire has now surpassed the Thomas in acreage and claimed the title of California’s Largest Wildfire in recorded history. The Ranch Fire is currently 317,117 acres with 69 percent containment. The main influence of the Ranch Fire during the upcoming operational will be winds speeds. With the predominant winds coming from the west, the fire will continue push east. As these winds diminish this evening the primary driving factor of fire spread will switch to the local topography. This will likely change the direction of spread to the northeast. With the fire continuing to spread to the Northeast, there will be no shortage of fuel as it furthers its destruction of the Mendocino National Forest. Fire crews have constructed containment lines in this area and are preparing for a firing operation if the opportunity presents itself.

Aerial Imagery, Carr Fire, Mendocino Complex

This image shows both the Mendocino Complex and the Carr fire’s smoke column from a satellites view.

Mendocino Complex Fire Facts

  • As of: August 16th, 2018
  • Location: Clear Lake, CA
  • Size: 366,037 acres
  • Containment: 76%
  • Fire Behavior: Moderate Fire spread through heavy timber and brush in steep, rugged terrain.
  • Structures Threatened: 1025
  • Structures Destroyed: 147 Residences/118 Other
  • Structure Damaged: 13 Residences/ 23 Other
  • Evacuations: Are in place
  • Incident Page: http://www.fire.ca.gov/current_incidents/incidentdetails/Index/2175
  • News Article: ABC 7
Earthquake, History.

Earthquakes – An Unpredictable Force of Destruction

Earthquakes have caused massive devastation, and amounted to huge numbers of human casualties since the beginning of recorded history. The problem with these natural disasters has become compounded by our cities becoming developed more vertically in the form of taller buildings without the proper respect given to earthquakes during the engineering process. Along with the previously mentioned factor, the general population that doesn’t live in earthquake prone areas won’t know what to do in a situation like this. You can learn more about how to prepare yourself, and what to do during an earthquake event in RedZone’s blog. This blog will hopefully assist in understanding the geoscience that is occurring before, during, and after one of these events takes place.

The Earth’s Crust and Earthquakes

Of the inner Earths four internal layers, the crust and the upper most portion of the mantle play the most vital roles in the unseen processes that power earthquakes. The Earth’s crust is made up of 12 major plates that are very dynamic in nature.

Tectonic plates and Earthquakes

This map displays the 12 major tectonic plates throughout the world.

It is here at the tectonic plate boundaries that the earthquakes originate. As the plate boundaries come to a resting place due to its jagged edges, the remaining portion of the plate remains in constant movement. When the energy from the movement of the rest of the plate becomes too much force for an area of the plate boundary to hold, the edges of these plates shift and this is what causes an earthquake. The earthquake we feel on the ground stems from the seismic waves that are produces when the tectonic plates shift.

There are two primary wave types that are produced by this tectonic shift, the P wave (primary) and S wave (secondary). P waves have also been called the compressional waves due to the way these waves push and pull the matter they are travelling through. S waves are the waves we feel on the surface that create the movement on the earth’s surface. S waves are much slower to appear than the P waves for a seismologist to read.

Seismographic Readings and Determining the Epicenter

Scientists with their particular field of study in earthquakes, track these waves to give the public a rating on the Richter scale of how strong in magnitude an earthquake is. These experts also utilize the seismographs to locate where exactly the epicenter was. Triangulation is used to determine the precise location where the epicenter is. Three seismographs measure the difference in times that the P waves arrive at the seismographs and compare them with the time it take for the S waves to arrive at the same location. A circle is then created around the three selected seismograph locations with the radius being determined off the aforementioned time difference in seismic wave arrival. The point at which each of the three seismographs calculated circles meet is the epicenter.

Epicenter of Earthquakes

This diagram depicts a visual representation of how the epicenter of an earthquake is found from three seismographs.

 

Predicting Earthquakes

Unfortunately scientists have been unsuccessful so far in the prediction of when the next earthquake will occur. Earthquake prediction is more often defined as the probabilistic assessment of general earthquake hazard, including the frequency and magnitude of damaging earthquakes in a given area over years or decades. Like many naturally-occurring phenomena, they are nearly impossible to accurately predict.  Prediction methods go back hundreds of years.j Methods generally involve precursors which among them include animal behavior, gas emissions, and even electromagnetic anomalies. Generally, Earthquake prediction is  thought of as an immature science with any claims of prediction found circumstantial and arguable.

Earthquake warning systems on the other hand have proven successful on a number of occasions especially in areas farther from an epicenter.  The effectiveness of the warning depends on the position of the receiver. After receiving a warning, a person may have a few seconds to a minute or more to take action. Areas near the epicenter may experience strong tremors before a warning is issued. Early warning systems have been prevalent in Japan, Mexico, Canada, and the United States for years.

Sources:

https://pubs.er.usgs.gov/publication/fs20163020

https://earthquake.usgs.gov/learn/kids/eqscience.php

https://earthquake.usgs.gov/learn/facts.php

https://www.nationalgeographic.com/environment/natural-disasters/earthquakes/

http://www.geo.mtu.edu/UPSeis/waves.html

DISASTER 101 – FLOODING

When most people think of natural disasters, the first thing to come to mind is not likely flooding. However, flooding is the most common natural disaster. Flooding occurs in all 50 states, accounts for 40% of natural disasters, averages 5 billion dollars in damage each year, and claimed an average of 75 lives per year over the last 30 years.

Worldwide, statistics are similar.

According to the 30 year average, flooding is responsible for the most weather-related fatalities.

TYPES OF FLOODING

River and Lake Flooding

River and lake flooding is probably what most people envision when they think of floods. Heavy rainfall or snowmelt can cause water levels to rise overflowing banks and levees. River flooding is common in the Midwest as rain and snowmelt swells the tributaries that feed into larger rivers downstream. Once the water level crests the river banks, the area that is inundated can be widespread. Low lying areas, saturated soils, and urban areas can further exacerbate the effects of the overflow and take days to dissipate.

California experienced flooding in February when a weekend of storms increased runoff from Anderson Lake and flooded low-lying areas of San Jose. The early year storms also prompted the evacuation of over 88,000 people near the weakened Oroville Dam.

In May of 2017, heavy rainfall over the Midwest caused widespread flooding. Nearly 15 inches of rain fell over multiple states, saturating soils, and swelling multiple rivers above historic levels. Numerous levees were breached which flooded towns causing an estimated $1.7 billion dollars in damages to homes, businesses, and infrastructure.

40% of all natural disasters are flooding.

Coast Guard overflight of South Carolina flooding

Coastal Flooding and Storm Surge

A form of flooding happens regularly along coastlines due to the cycle of rising and lowering tides. Tides are a regular rise and fall of sea level caused by the gravitational interplay of the sun, moon, and earth. Occasionally, these tides can be exceptionally high. An increase of just a few feet is more than enough for tides to breech natural and man-made barriers. Many coastal cities are very near, or in some cases lower than, sea level making them especially prone to any change in sea level.

Storm surge can also cause extreme coastal flooding. The surge develops during severe weather, hurricanes, and tropical storms raising sea level as much as 25 feet. Sea level rise is the result of the low atmospheric pressure found in these storms which has a similar effect on sea level rise as the gravitational pull on tides. High winds common with these storms also cause large waves to batter the coast and push water farther inland. In worst case scenarios, the storm surge strikes the coast during a high tide cycle, increasing the flooding exponentially. Storm surge flooding is responsible for 90% of hurricane related deaths and the majority of the damage to structures.

In August of 2017, Hurricane Harvey alone caused over $125 billion dollars in damage and killed 89 people. The majority of the devastation caused by Harvey was a direct result of the widespread flooding of the Houston area.

Flash Floods

Flash floods can result from a variety of causes, but the common denominator is that they develop quickly and are normally caused by heavy rainfall. These floods can also be the result of snow melt, dislodged ice, inadequate urban drainage, or dam breaks. The actual volume of water carried in a flash flood is usually less than other flood types but the water is channeled down confined spaces which causes it to move with devastating force and speed. Because of this speed, flash floods are very dangerous, easily carrying mud, rocks, and trees in its flow. A Weather Channel article stated that, “water flowing at 7 mph has the equivalent force per unit area as air blowing at EF-5 tornado wind speed.” Whereas, “water moving at 25 mph has the pressure equivalent of wind blowing at 790 mph, faster than the speed of sound.”

 

BASIC SAFETY AND PREPAREDNESS

Ready.gov provides many helpful tips.

Be Mindful

  • Stay tuned to phone alerts, TV, or radio for weather updates, emergency instructions, or evacuation orders.
  • Avoid walking or driving through flood waters. 6 inches of moving water can knock a person over, and one foot of moving water can sweep a vehicle away. According to the Environmental Protection Agency, the leading cause of flood-related injury and death is individuals attempting to drive through flood waters.
  • Do not drive over bridges that are over fast-moving floodwaters. Floodwaters can scour foundation material from around the footings and make the bridge unstable.
  • If there is a chance of flash flooding, move immediately to higher ground.

Protect your home

  • Know your flood risk, avoid building in flood plains, and consider buying flood insurance.
  • If you have to evacuate due to flooding, and if safety permits, turn off all the utilities to your home and attempt to move valuables to the highest possible level.

SOURCES

https://www.ready.gov/floods
https://www.nssl.noaa.gov/education/svrwx101/floods/types/
https://www.ncdc.noaa.gov/billions/events/US/2017-2018
http://www.floodsite.net/juniorfloodsite/html/en/student/thingstoknow/hydrology/floodtypes.html
https://weatherology.com/articles/106/The+Dangers+of+Flash+Floods.html
https://weather.com/storms/severe/news/power-flood-water-20130704
https://www.livescience.com/23913-flood-facts.html