Did You Know? Puerto Vallarta in Mexico will become an island and float away

articles History & People

Tony Burton

Did You Know…?

Literary-minded travel writers describing Puerto Vallarta as an “island of tourist delights” probably don’t realize that their words are closer to the truth than they might imagine. At present, Puerto Vallarta has plenty of tourist facilities but is certainly not an island. The Pacific Ocean may swish against Vallarta’s beaches on one side, but there is no ocean in any other direction where land-based highways link Vallarta to inland centers like Tepic and Guadalajara. But, Vallarta’s coastline is slowly changing . . .

Geologists have long known that the relative levels of sea and land have not remained stable during geological history. At some times in the past, sea level has been much higher than at present, at other times much lower. Palaeogeologists have worked out maps showing the distribution of land and sea for most parts of the world going back hundreds of millions of years.

The situation is complicated, of course, by the migration of the global “plates” into which the earth’s thin outer crust is thought to be divided. Movements of these plates provoke earthquakes, volcanoes and other major upheavals and cause mid-ocean ridges, fold mountains and volcanic belts like Mexico’s Neo-Volcanic Axis.

Recent studies of the structure and evolution of western Mexico demonstrate the probability that, in the not too distant (geologically speaking) future, the coastline of the region will be completely different to what it is now.

From Guadalajara, it will be only a 30 minute drive to the new coastline located close to Ajijic and Lake Chapala. Parts of the Guadalajara-Colima highway will be washed into the sea as they are undercut by Pacific breakers and collapse 3,000 feet (1,000 meters) or more into the surf.

Meanwhile, Puerto Vallarta will be the largest city on a small, mountainous island floating slowly westwards towards Hawaii.

Far-fetched? Not at all. Geologists have worked out that three major lines of faulting are slowly cracking open western Mexico. The first is east-west along Lake Chapala – the lake occupies a rift valley formed by parallel faults that caused the section of land between them to fall, creating a basin large enough to hold the lake.

The second line of faults is from Guadalajara westwards towards Tepic in the state of Nayarit. Highway 15 follows this line of faults and movements here have allowed several noteworthy volcanoes to form including Tequila, Sanganguey and Ceboruco.

The third line of faults has caused the long shallow depression used by the Guadalajara-Colima-Manzanillo highway – the “dry lakes” area, as locals call it.

Time to consult the map! If you mark these three lines of faults on your road map, you’ll discover that they intersect just west of Lake Chapala. What is really happening is that a triangular “island” of land (including Puerto Vallarta) is splitting off from the “mainland” and will shortly drift westwards into the Pacific Ocean. Once Puerto Vallarta has broken away (and, in all probability, Manzanillo has been crushed and melted back into the nether regions of the earth), Mexico’s Pacific coastline will follow the line Mazatlan – San Blas – Tepic – Tequila – Santa Anita (Guadalajara) – Colima – Tecoman – Ixtapa, instead of its present route.

You still think it’s far-fetched? I’m afraid not. The epicenter of the largest earthquake in historic times near Lake Chapala was immediately under the town of Zacoalco, just south of Guadalajara. On December 27, 1568, this magnitude 7 quake damaged churches, houses and convents throughout the region. Furthermore, several of the so-called “coastal” earthquakes in recent years have actually had epicenters under land, not under the ocean at all, adding further weight to the idea.

Not, of course, that all this is going to happen overnight. At an estimated rate of movement of about an inch (2.4 centimeters) a year, it may take a while for the movement of Puerto Vallarta to become obvious. But, even if airlines aren’t yet panicking over this annual increase in flying distance (and time) between Guadalajara and Puerto Vallarta, real estate advertisements seem certain to look very different in a million year’s time:

For sale: desirable water-front property on the island of Vallarta, with fantastic views across to Tequila beach and the Jocotepec waterfalls where Lake Chapala drains into the ocean…

Published or Updated on: March 14, 2008 by Tony Burton © 2008
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