Quake Prep

 Since experiencing a 7.9 quake (thankfully from 65 miles away) as a young teenager, I've been fascinated with earthquakes. Not enough to center a career around them, but enough to make some effort to learn about them, their hazards, and what I can do to better prepare my home and family. Here I want to bring some of my earlier posts together to help give more meaning to an image that depicts the magnitude, energy, intensity, and frequency of earthquakes.  The magnitude is the size of an earthquake. Originally this was measured on the Richter Scale  which basically measures how big the shaking is. But this scale becomes less accurate for measuring quakes from further away, and it's not very good for measuring big quakes. A full step for example from 5.0 to 6.0) is an increase of 10 times. In the 1970s the Moment Magnitude Scale was developed. Where the Richter Scale was more about size, Moment Magnitude measures how much energy is released. It's another type of big, only...

 Maybe it's a bit of a curious fascination, but I find it interesting all the different ways we could face disaster. When I gave a general preparedness class one of my opening bits was a list of some of the human and natural disasters that can create an emergency situation. Then I jumped from the local and regional disasters to civilization-ending. This article popped up in my news feed  A giant space rock demolished an ancient Middle Eastern city and everyone in it – possibly inspiring the Biblical story of Sodom  and it's republished from The Conversation. Here's the theorized description of how that Middle Eastern city met its end: "As the inhabitants of an ancient Middle Eastern city now called Tall el-Hammam went about their daily business one day about 3,600 years ago, they had no idea an unseen icy space rock was speeding toward them at about 38,000 mph (61,000 kph). "Flashing through the atmosphere, the rock exploded in a massive fireball about 2.5 miles (...

 In my post Earthquake Early Warning  one of the earthquake early warning systems mentioned was QuakeAlert. Developed by Early Warning Labs , who partnered with USGS, QuakeAlert's objective is to quickly detect the initial energy waves produced by an earthquake. These first energy waves, called P-waves, rapidly radiate from the epicenter.  Using P-waves the location, magnitude, and anticipated ground shaking (this correlates to possible damage is basically what the Mercalli Intensity Scale attempts to quantify) can be estimated. Based on these estimations warnings are distributed to state emergency response, critical infrastructure, businesses, and the public before the damaging S-waves hit. The S-waves are when the real shaking and damage occur. Depending on the earthquake's magnitude, depth, and other factors, such as ground composition and your distance from the epicenter, your warning may give you up to 60 seconds before the earthquake strikes. The expectation is to ...

  Since rankings tend to vary from site to site and year to year, but the highest earthquake risk cities tend to remain in the rankings, the cities are listed in alphabetical order. In the S through Z we'll look at San Francisco, Salt Lake City, Seattle, Tulsa, Washington D.C., and Wichita. For reference, here's the USGS earthquake hazard map. San Francisco, California Overall, California has a greater than 99 percent probability of one or more magnitude 6.7 or larger earthquakes occurring by 2037. However, while the probability is greater for Southern California, Northern California’s chances are 93 percent for a magnitude 6.7 earthquake during that time frame. A magnitude 7.0 has a 68 percent probability, while a 7.5 has only a 15 percent chance of occurring. Focusing on the San Francisco area, the USGS gives the region a 63 percent chance of a magnitude 6.7 or larger happening by 2037 ( UCERF3: A new earthquake forecast for California's complex fault system ). Salt Lake ...

 Since rankings tend to vary from site to site and year to year, but the highest earthquake risk cities tend to remain in the rankings, the cities are listed in alphabetical order. In the M through P we'll look at Memphis, New York City, Oklahoma City, and Portland. For reference, here's the USGS earthquake hazard map. Memphis, Tennessee Memphis lies within the earthquake hazard risk area of the New Madrid Seismic Zone, which is why it is one of the top cities in the U.S. for earthquake risk. According to the USGS, a magnitude 6.0 or greater earthquake has a 25–40% probability of striking the area within the next fifty years.  New York City, New York Some people are surprised that New York City has an earthquake risk. Although the area isn’t as seismically active as Los Angeles, there are faults all over—or, more accurately, all under—the area. Historical evidence suggests a moderate quake of at least 5.0 should shake the area about every hundred years. The last one to strike ...

 Since rankings tend to vary from site to site and year to year, but the highest earthquake risk cities tend to remain in the rankings, the cities are listed in alphabetical order. In the A through L we'll look at Anchorage, Charleston, Dallas, Honolulu, and Los Angeles. For reference, here's the USGS earthquake hazard map. Anchorage, Alaska California usually takes the headlines for earthquakes in the U.S., but Alaska has the highest earthquake risk. It’s not uncommon to hear about a large earthquake in Alaska. However, since the population density is extremely low, few people are affected, making the event not very newsworthy. Anchorage has a population of around 300,000. While not as large as some of the other cities mentioned, if an earthquake were to strike the city, considerable damage, injuries, and even fatalities would occur. Most of the negative effects may not come from the earthquake itself but as the result of an earthquake-caused tsunami. Recent studies of the sea...

Rounding out the top 16 states in the U.S. with the highest earthquake risks are Arkansas, Illinois, Kentucky, Missouri, South Carolina, and Tennessee. The biggest threat to these states is the New Madrid Seismic Zone. Arkansas The biggest earthquake risk in Arkansas lies in the New Madrid Seismic Zone. The 19 counties in northeast Arkansas, those that stretch out from the Seismic Zone, are at greatest risk. A magnitude 7.7 New Madrid earthquake would likely damage 162,000 buildings and 1,100 bridges. The number of casualties could be as high as 15,300, and direct economic losses might top $40 billion. In 1976, a magnitude 5.0 earthquake struck Poinsett County, Arkansas. Illinois Southern Illinois is near two significant earthquake zones. The most notable is the New Madrid Seismic Zone, which poses a high risk to several states. The second fault zone is the Wabash Valley Seismic Zone, where a magnitude 5.2 earthquake shook the area in April 2008. Prior to that, a 5.3 quake caused some ...

 Like Washington, the greatest threat to Oregon lies in the Cascadia Subduction Zone. A magnitude 9.0 Cascadia event would likely cause damage to 38 percent of the buildings in Portland. In this scenario, tens of thousands could be injured or killed, while more than 250,000 could experience long-term displacement. Building damages could range from $23.5 billion to $36.7 billion as a result of the event ( Open-File Report O-18-02, Earthquake regional impact analysis for Clackamas, Multnomah, and Washington counties, Oregon ). But a Cascadia earthquake may not even be the worst-case scenario. Stretching from Oregon City to Scappoose lies the 30-mile-long Portland Hills Fault. Estimates of a large quake striking that fault are less than the Cascadia Subduction Zone, but it would be more devastating. The Portland Hills Fault is estimated to have only had two large seismic events during the last 15,000 years. Still, if a large earthquake were to hit, its devastation could be far worse t...

 Easily ranked in the top 10 states with the highest earthquake risk, Utah's primarily risk lies among the Wasatch Fault Zone. The following image is of a building damaged in the February 2011 Christchurch earthquake in New Zealand. There have been several comparative studies done between New Zealand buildings damaged by earthquakes and similar structures in Utah. Utah The Wasatch Fault Zone stretches about 240 miles from southern Idaho into northern Utah. While it is the longest fault zone in the area, it’s not the only one. Other large fault zones in the area include the Oquirrh-Great Salt Lake, West Cache, Stansbury, and Eastern Bear Lake fault zones.  The Wasatch Fault is at the base of the mountain range that runs through the state. Along the urban corridor, this section of the mountains is referred to as the Wasatch Front. With many communities built along the foothills, a major seismic rupture could not only cause a lot of liquefaction damage in the lowlands but hundred...

States generally ranked as the sixth through eighth highest earthquake risks are Wyoming, Idaho, and Montana. Wyoming Earthquakes have occurred in every county of Wyoming. However, the most seismically active area is the northwest region, where Yellowstone National Park is located. Historical records indicate that earthquakes as strong a magnitude 6.5 are possible in most parts of the state. Several faults in western Wyoming are capable of magnitude 7.2 to 7.5 ruptures, including the Teton Fault, Star Valley Fault, Greys River Fault, Rock Creek Fault, and Bear River Fault. Recent studies have led researchers to conclude that many of these fault systems are past due for big quakes. The largest recorded earthquake in Wyoming occurred on August 18, 1959, in Yellowstone National Park. It was a magnitude 6.5 event and was considered an aftershock of the magnitude 7.2 Hebgen Lake earthquake that struck southwestern Montana the night before. Despite the headline grabbing attention of the thre...

In most top earthquake risk states in the U.S., Alaska, California, Hawaii, Nevada, and Washington top the list. Alaska  Alaska is the most seismically active region in the United States. But the lower population means there isn’t as much devastation to report.  That said, the second-largest earthquake ever recorded shook southern Alaska in 1964 with a magnitude of 9.2. In 2002, a magnitude 7.9 earthquake struck the Denali Fault in central Alaska. Another 7.9 hit on January 23, 2018, near Kodiak Island. Since 1899, six additional quakes in the magnitude 8 range have struck. Overall, Alaska has about 11 percent of the world’s recorded earthquakes. Three of the eight largest earthquakes were in Alaska. Narrowing earthquakes to the United States, seven of the ten largest were in Alaska. Southern Alaska is near the Alaska-Aleutian Megathrust Fault Zone, which is one of the most active and dangerous on Earth. On average, since 1900, Alaska experiences a magnitude 8.0 or larger eart...

 Here's the scenario. An earthquake strikes your area. It's a big quake, maybe a 5.8 to 6.2. It causes some damage and injuries. But, all of the predictions of the overdue earthquake are for a magnitude 7.0 to 7.4 rupture.  In this scenario you'll likely hear predictions that the quake is a foreshock and the BIG ONE is imminent. And you'll hear people claim that the fault released pressure so the BIG ONE isn't likely to strike very soon. These are the two general theories of thought about how "big" earthquakes--that aren't as big as the BIG ONE that is expected (or usually seen as "over due" for the fault)--affect the potential for the BIG ONE to strike. First, some people believe that an earthquake of a higher magnitude will release stress on the fault and delay the occurrence of a larger earthquake. So, if a 6 happens instead of the 7, they believe the "Big One" will happen later, rather than sooner, because some stress on the fau...