While earthquake victims are struggling for the basics of life in Kobe, Japan, the Utah Legislature is studying a set of recommendations by the Utah Seismic Safety Commission that could help the state prepare for a quake.
The chilling fact is that all of Japan was much better prepared for earthquakes than Utah is. Yet the threat to Utah may be nearly as high.By coincidence, the list of 33 strategies was delivered on Jan. 10 - exactly one week before Kobe was devastated by an earthquake registering 7.2 on the Richter scale.
At 1.5 million people, Kobe is much larger than Salt Lake City. In fact, its population is only 200,000 fewer than the total number of Utahns tallied in the 1990 census. So its overall scale of damage must be larger than could be expected if, for example, the Wasatch Fault slipped in Utah's capital.
Still, an earthquake of 7.5 on the Richter scale centered in the Salt Lake region would kill an estimated 7,600, with 44,000 injured. If the dams above Salt Lake City were to collapse, the estimated toll would rise to 24,000.
Kobe's earthquake registered 7.2 on the Richter scale, while the Wasatch Fault's "maximum credible event" is rated at 7.5 or 7.6. In terms of amount of energy released, that's twice as big as the Kobe shaking.
The Richter scale is confusing in that it is usually thought of in terms of ground motion, with each additional whole point - from 7.0 to 8.0, for example - representing a tenfold increase. The confusion comes in that ground motion is not the same as energy released.
"A magnitude 7 is 33 times bigger than a 6 in the amount of energy released," said M. Lee Allison, director of the Utah Geological Survey and the state geologist."Based on the size of the faults that we have here and our research looking at prehistoric earthquakes, we believe that the Wasatch Fault is capable of a 7.5 or a 7.6 earthquake."
The next question is always, when will it happen? "We could be looking at an earthquake twice the size of the one that hit Kobe. It could happen tonight, it could happen tomorrow, it could happen in 50 years - it might not happen for a couple hundred years," Allison said.
But seismic studies show some frightening facts about Utah quakes. Along the Wasatch Fault that stretches throughout the most populous parts of the state, a quake of an average size of 6.5 has struck about once every 280 years. It's been 400 years since the last major one.
Worse, said Allison, "it may not be the Wasatch Fault that's the one that breaks loose."
The once in 280 years figure applies only to the Wasatch Fault. But northern Utah is riddled with other potentially deadly faults, from the Oquirrh Fault Zone along those mountains to one on Antelope Island, a series underlying Utah Lake, some large faults north of the Great Salt Lake to a big one on the east side of Skull Valley, Tooele County.
"There's two or three faults in the area of West Valley that are exposed on the surface," Allison said.
In fact, the Great Salt Lake and Utah Lake themselves are where they are because this is where water remained after prehistoric Lake Bonneville drained off. The reason these basins were the lowest points in Bonneville's basin is that they are "low spots probably created by fault movements over millions of years."
Still, Allison added, "The Wasatch Fault is kind of the mother of all faults in Utah."
What does that mean for Utahns? The level of damage in Kobe is roughly similar to what geologists have been predicting could happen along the Wasatch Front.
"In fact, for an earthquake of the same magnitude, we're fearful of more deaths, more damage and more injury," because Utah is not as well-prepared, Allison added. Japanese officials have been holding earthquake drills and making plans for many years.
Until the early 1960s, by which time many of the buildings throughout Utah were already built, the state did not have building codes that would protect against earthquake damage.
"We have more unreinforced masonry buildings in the Salt Lake Valley than the entire state of California," Allison said. These buildings are heading for a fall in case of a bad shaking.
This area has what the survey chief calls "a major liquefaction problem." Relatively unstable soil turns to mush during a big earthquake and buildings can fall over.
The region's potential for liquefaction is "as bad as anywhere else in the world. . . . Our soils in many ways look like Mexico City."
Liquefaction there amplified the ground shaking during Mexico City's infamous earthquake of 1985.
The Utah Seismic Safety Commission outlined 33 points that are supposed to help Utah meet the quake danger. The commission is supported by the Utah Geological Survey and the Utah Division of Comprehensive Emergency Management.
The final report, delivered to the Legislature, lists five top priorities:
- Improve earthquake awareness and education by telling Utahns about the hazards and risks.
- Improve emergency response and recovery. Community emergency response teams should be established throughout the state. Emergency communications should be upgraded.
- Improve the seismic safety of buildings and infrastructures. Buildings that are needed for essential services should be retrofitted so they could keep operating after a quake. Older school buildings should be reinforced.
- Improve essential geological science information by incrementally developing a program to detect strong ground motions.
- Assess the earthquake risk. Estimates of direct losses that could be expected from earthquakes should be updated.
S.L. quake could cause $12 billion damage
Latest estimates of loss in case of a magnitude 7.5 earthquake in the Salt Lake area show that Salt Lake County alone could suffer about $12 billion in direct costs.
Indirect costs, for wages lost over the ensuing six months, would amount to $6 billion in downtown Salt Lake City, said M. Lee Allison, state geologist and director of the Utah Geological Survey.
Allison cited figures approved by the Federal Emergency Management Agency for the region of Salt Lake, Davis, Utah and Weber counties. Some of the figures have been updated recently.
Casualty lists could be appalling. In Salt Lake County alone, 7,600 might die, with 44,000 injured - if the dams don't fail. If the earthquake caused dams to collapse, the dead could number 24,000.
Another 45,000 people would be homeless. More than half of all emergency response ability, such as fire and police protection, would be lost.
Salt Lake International Airport would be knocked out, a quarter of the natural gas lines would be disrupted, and 500,000 people would have no sewage treatment.
Because of damage to oil refineries or problems with transportation, petroleum products would be unavailable for nearly all of Utah and Idaho, leaving about 2.7 million people isolated.
Half of potable water supplies would be out, leaving 646,500 people without water for an extended period.