[EAS] WEA used in NYC bombings

[John Willkie]

Mike McCarthy wrote:

"On the mass transit side alone, if they emergency stop or lock-out the
trains before the waves hit, they avoid derailment. Countless lives can be
saved and injuries avoided or minimized by simply keeping the trains on
their tracks and avoiding collisions. Mind you, it won't stop above grade
cars from tipping over during the event. But at least their travel will be
halted. And if they do topple, chances are likely they would have derailed
and crashed regardless. So while the outcome is still unfavorable, it is
the least unfavorable of the scenarios."

We have data points that we can apply against this concern.  Transit has very low ridership numbers in California, with the Bay Area leading the pack.  In the 1989 Loma Prieta quack, which I "experienced" in Washington, DC on live TV, there were several BART derailments, but I don't remember any loss of life or serious injuries underground or even above ground.  There were serious concerns about passengers trapped in underwater tunnels, and BART already had automatic train-stop mechanisms which more or less went into effect.  BART is a third rail system.  There would be zero advantage to sending out alerts in that scenario, because the epicenter is too close to the population center; the waves will travel and do damage before electrons have had a chance to put on their socks.

The major loss of life in that quake wasn't near the epicenter, but in Oakland, where the Cypress structure, carrying hundreds of thousands of people home (slowly) in "rush hour" collapsed -- no "pancaked" turning hundreds of people into memories. 

This is the earthquake that Jim Berkland "warned about" but he would never claim that he predicted it, because he could never get to the "place, time and magnitude" criteria..  As he explained hundreds of times later, his trigger mechanism would start with noticing a surge in "Lost Pet" notices in the newspaper, notices that would somehow peak a day or two before the temblor.  He had other "confirming" criteria, but his trigger was public notices of lost pets. I remember him going on the radio in the last decade or two, drawing attention to earthquakes that didn't happen or weren't threats.  I do remember him warning of the Napa quake.  I don't remember loss of life in the Napa quake; some historic and reinforced structural elements fell to the ground, and an AT&T switch/fiber hub went down.

The Cypress structure had been built upon alluvial fill, and even at the time, it was suspected that areas over alluvial fill suffered worse in earthquakes than areas built upon rock.  The term is "liquefaction" of terra firma.  I think that is a perfect and cautionary term.  There were some building collapses in the Loma Prieta quake in the Mission District of San Francisco. 

So, give those people driving home from work in 1989 and give them a two-minute warning of the earthquake.  What will they do?  Where will they go?  The Cypress three-level structure was a long one.  ISTR that at least one person attempted or tried to attempt to jump off, but I can't remember the fate.

I don't see why one would need to put braking systems on transit cars.  There are many cars, all mobile, but few power stations, all fixed.  Removing power from cars will slow them and ultimately all will stop.  Removing power means that the most powerful brakes on (at least some) cars wont work, because if you have no power, you have no ability to use counter-electromotive force.  Transit cars do have high centers of gravity, but side-to-side forces create the toppling hazards.

Subsequently, Caltrans started a slow process of examining every overpass they owned in the State of California for structural integrity against local ground conditions and began the slow process of upgrades. 

I'll pass by the Landers cluster of 1992.  While that highway upgrade was in progress, we experienced the Northridge quake, at 4:30 am January 17, 1994.  The magnitude was 4.7, but the most relevant criteria was that it was the largest amount of ground acceleration (in this case up/down, not lateral) that had ever been recorded in an urban area.  LA didn't have any mass transit to speak of at the time, except the rubber-tired type.  The major single-point loss of life were the people in apartments almost exactly over the epicenter whose apartments were on a second story and their cars parked underneath.

Damage was widespread.  Aside from that apartment complex, there was wide spread damage of unreinforced homes.  In those areas, at least as many deaths were caused by house fires.  The failure mode was gas lines being broken, water heaters tumbling, with sparks.  But, gas mains were also severed. 

One highway patrolman (officer Clarence Wayne Dean) riding to work on his motorcycle in the Antelope Valley, died when the overpass section in front of him collapsed.   An overpass on Interstate 10/Santa Monica Freeway, which ISTR had already been upgraded, collapsed and was back in action within 90 days.

I don't understand, to be frank, having alerts go out to turn off gas mains, as most buildings of size are already required to have automatic gas cut-offs triggered by ground movement.  All water heaters in the State of California are required to have a wide metal band that holds them against a wall, which mitigates the risk.  Having automatic cut-offs in many or most homes might mitigate the risk to gas companies, but people without power and gas but without any damage to their home were p**sed in 1994.  The people who survived the quake itself but were trapped in a home that burnt down had few people speaking for them.  Most hadn't secured their water heaters.

Automatic turn offs work, but turning them back on creates liability, and that process is manual.  A month of cold showers seems like a big price to pay for a false positive that was widely transmitted and acted upon in private homes.

Elevator lockouts seem like a good idea, but many more recent elevators (particularly express ones) already have that capability, based on ground motion.  All elevators are programed to come to the nearest floor, open the doors, and lock out controls until reset by emergency personnel.  It is hard to imagine the corner case where remote alerts would improve this.  Perhaps there was a loss of life in an elevator cab during an earthquake, but I can't recall one.  Removing people trapped in elevators takes much time that could be devoted to more pressing concerns after a quake.

My family has lived in CA a few generations less than Bill's, but I tend to not feel quakes < 3.8.  One night a year or so back, I was in bed and had settled down.  I felt a subtle rill in the ground and noted the time.  Next morning, the news told about a quake around 3.2 about centered about 90 miles away at the time I had noted.  I didn't consider it newsworthy.

A few weeks ago, I saw a news report on the Oklahoma swarm.  Two Okie women had an app on their phones that told them every earthquake in the state, and they were concerned about each one as they thumbed through the list.  I know that quakes are a new concern for Okies and their swarm seems to have a man-made origin, but I asked out loud "Why in the h**l would someone have such an app on their phone?"  Has anybody in the State ever been killed or even lightly injured in a quake?  How does a quake earlier in the day in a distant region affect you in any way?  It's just earthquake porn.

John