After the big quake what is next for Mexico?
The following is an article originally published in the HuffPost. I contributed to the Huffpost on the topics of diplomacy, Mexico, and technology. At the bottom of this repost there will be a link to the original article.
The Southern California Earthquake Center at the University of Southern California has been at the forefront of earthquake sciences for decades. The brand new director of the center, Dr. John Vidale, has answered a few questions about the September 19, 2017 earthquake that struck central Mexico. The effects on Mexico City have been caused many deaths and a lot of fear in the general population. Here are some facts to some of the most asked questions.
Is the Earthquake that hit Mexico City on September 19th unusual? Is it something that could have been anticipated?
The earthquake that just hit Mexico City is uncommon but not surprising. There have been many earthquakes in a similar place with a similar tectonic style, including one in June 1999 that was just a touch deeper and farther away and smaller. So geologists knew this exact quake was possible — and one with similar levels of shaking strikes every few decades.
Why have there been no aftershocks? Could it be possible this earthquake may be followed by a larger more powerful quake?
There have been several dozen aftershocks detected, but they are small to tiny. This scarcity of aftershocks is often seen for such deep earthquakes. The M7 Nisqually earthquake that hit Seattle in 2001, for example, only ever had 3 or 4 aftershocks detected, the biggest an M4.
Are there any signs or early warnings that can proceed another big quake?
No. The M8 12 days prior, hundreds of km to the southeast, may have slightly raised the odds of earthquakes this month in southern Mexico (or maybe it is unrelated). The only precursor proven to indicate elevated risk of an earthquake (NOT prediction of a specific event) is another earthquake — the rule for shallow earthquakes is that any quake has a 1 in 20 chance of being followed by a (generally slightly) bigger earthquake. The odds of a bigger ensuing earthquake are even lower for deep earthquakes. But one can already find many claims of successfully predicting this earthquake on the wild and woolly internet, of course.
What can science tell us about the future of quakes for Mexico?
The lessons from this earthquake for Mexico are the same as the lessons from bad quakes in subduction zones across the globe. There are several flavors of dangerous quakes — large and great quakes near the coastal fault line, large deeper quakes around the cities, and moderate to large quakes on secondary faults shallow under the cities.
For Mexico, this quake shows there is still a lot of work to do before its cities are quake-safe. This is far from the worst quake that could hit Mexico City. Hoping for the best is just playing the odds, not a responsible policy, and study, planning, and fixing vulnerabilities will be necessary for quite a while.
You can learn a more complete bio of Dr John Vidale at his University Of Washington home page.
