Seismic standardsLA to require seismic standards for new cellphone towers

Last Friday Los Angeles became the first U.S. city to approve seismic standards for new cellphone towers, part of an effort to reduce communications vulnerabilities in case a large earthquake should strike. The last major earthquake in Los Angeles was the 1994 Northridge quake, before cellphones and WiFi ruled the communications landscape.

According to U.S. Geological Survey seismologist Lucy Jones, who advises Los Angeles mayor Eric Garcetti on seismic matters, the 2008 magnitude 7.9 earthquake in the Chinese province of Sichuan, offers insight on how current cellphone signals will hold in the aftermath of a large quake because Sichuan used similar building standards for cellphone towers as the United States. In the Sichuan case, more than 2,000 cellphone towers were disabled, leaving communications gaps that lasted weeks.

The Los Angeles plan requires new freestanding cellphone towers to be built to the same seismic standards as public safety facilities. Cellphone towers are currently built only strong enough not to collapse during a major earthquake. There are not required to be strong enough to continue working. “This is about earthquake functionality. It’s about getting us back on our feet,” said Jones. “This is really sort of a first time that, looking forward, we said the government’s role goes beyond just saving lives, and has a role in making sure that our economy is up and functioning after a disaster,” she added.

Public safety officials became aware of the communications vulnerabilities of cellphone towers during the magnitude 5.5 Chino Hills earthquake in 2008, when some mobile providers reported up to an 800 percent increase in calls, overwhelming the networks.

The Los Angeles Times notes that the new seismic standards will not require a retrofit of existing cellphone towers, as that would be just as expensive as building new ones. Building cellphone towers that meet new seismic standards will increase construction costs by up to 20 percent. The standards will not apply to new towers attached to buildings, which currently make up about 60 percent of cellphone transmitters in Los Angeles. The new standards will not guarantee that cellphone towers will be in operation under widespread power failure. Many cellphone towers have a battery supply that lasts as little as four hours. City leaders considered requiring larger backup batteries for cellphone towers but the options would have faced opposition from network providers. Cellphone transmitters require air conditioning to work properly, and adding backup generators to supply cooling would be costly. “We’re not trying to solve all the problems,” Jones said. “We are trying to reduce the problems … so that we reduce the chances we’re going to damage the economy.”

Network providers, who worked with the mayor’s office on the standards, have welcomed them. “The issue of network resiliency as a whole is a monumentally important one for the company,” said Alexandra Krasov, spokeswoman for AT&T. The company has already developed portable, makeshift cell towers that can be sent to locations that need additional coverage support. The towers are used for major concerts and sporting events.

The cellphone tower law is one of many major earthquake safety improvements Los Angeles officials are exploring. Garcetti has proposed an agreement with network providers to share network and wireless Internet access with customers of other networks during an emergency.