Volcan de San Juan

Overview

The Gate to Hell

Volcán de San Juan is one of the three volcanoes of La Palma, which broke out in 1949 in a massive eruption. The other two are Pico Nambroque with its Cráter del Hoyo Negro and Montaña del Fraile with its Cráter del Duraznero. All three volcanoes erupted at the same time, creating huge lava flows, which came down the slopes threatening - and in the case of San Juan even burying several villages (rather parts of them) underneath.

Moreover the three simultaneous eruptions created a huge crack in the Cumbre Vieja Range, which now is expected to cause a massive landslide of up to 500 billion tons whenever there is another eruption of the same scale. This in return would cause a mega tsunami which would race towards the Caribbean and the North American seaboard. See the next section for some more information on this.

Volcán de San Juan itself today is almost hidden on the upper western slopes of the Cumbre Vieja range. It would be easy to overlook it, hadn't it spilled those huge and impressive lava flows, the Coladas de San Juan. It buried parts of the villages of San Nicolás and Las Manchas on its way down to the sea. Part of these flows have been put under protection and declared Monumento Natural del Tubo Volcánico de Todoque. The mountain itself is part of the Parque Natural de Cumbre Vieja.

To the north of Volcán de San Juan you can find the large plain of Llano de Jable, a black scree field which only occasionally is interrupted by a lone pine. All in all the whole area appears to be quite hostile to life.

Geography of La Palma and the Mega-Tsunami Theory

La Palma as seen from the ISS

First of all let me state that I will post this section to all La Palma pages which I intend to post here. Both topics, the geography of the island as well as the Mega-Tsunami Theory are far too interesting to be left out. So if you have read it somewhere before, just skip this section.

Geography
La Palma, like said above and like all the other Canarian Islands is of volcanic origin. Actually you can draw a pretty accurate comparison to the Hawaiian Islands since both groups are similar in many respects. The Canarias have been formed 25 - 2 million years ago with La Palma one of the youngest islands together with tiny El Hierro. What strikes us most today is that the ocean floor around and between the islands is about 4000m deep, which makes mighty Teide (3718m) on Tenerife a truly impressive mountain if you consider the elevation from the ocean floor.

La Palma is not quite as impressive but it is the second highest of the Canarias with its highpoint, Roque de los Muchachos at 2426m. On the other hand it is the third smallest of the islands and thus the ratio of overall material to island area is the largest you will find for any island on earth. This makes it the prime candidate for causing the next mega-tsunami (see below).

The Island can be divided in three mountainous regions:

• the Caldera de Taburiente in the north, the world's largest erosion crater with a diameter of 29km and with caldera walls up to 2000m deep! The caldera is the leftover of a huge volcano which used to exist ages ago and which collapsed by sliding to the west of the island 550.000 years ago.
  
• the Cumbre Nueva, also the leftover of an even larger volcano. If you look at the little map you will see the Cumbre Nueva in the centre of the island. If you take the curvature of the cumbre and prolong it you will see just how large it really was. This volcano also dropped away to the west of the island.
  
• the Cumbre Vieja. Though viejo means old, this is the youngest part of the island by far. Here you can find 120 volcanoes, all very close to each other on this mountain range, which reaches 1945m in height. It is here that the next landslide to the west of the island is expected which is supposed to cause a devastating mega tsunami.

The Mega Tsunami TheoryClick here for the original scientific paper found by rbi.

To make it short: in 1949, three of the volcanoes (San Juan, Montaña del Fraile and Pico Nambroque) of the Cumbre Vieja erupted simultaneously. Large lava flows covered the western parts of the island and there were a lot of heavy earthquakes. During the eruption a large crack developed and the western part of the Cumbre Vieja slipped by 4m (12ft). Since deep chimneys have been found in the higher regions of the range, which all consist of porous, water-filled rocks, it is expected that the next eruption in this central region of the Cumbre Vieja will be so explosive, that the crack of 1949 widens and eventually the western part of the Cumbre Vieja would tumble into the sea. With huge amounts of material (500 billion tons) rushing to the sea huge waves would be created, which finally will hit the US and the Gulf of Mexico with devastating effects.

Since La Palma and neighbouring El Hierro have a history of these massive landslides a scenario likes this seems feasible. But nobody knows when - or even if - this will happen. Heavy eruptions occur every 200 years on La Palma and it is far from clear that the crack, which developed in 1949 actually is deep enough to split the island in two.

Getting There

La Palma, like all the other Canarian Islands can easily be reached from almost all major European airports. The airport is rather small and compared to Tenerife or Gran Canaria air traffic is rather low. There are almost no regular flights but all year round you'll be able to book charter flights.

There are several possible ways to reach Volcán San Juan since there is a well kept web of hiking trails in the area. The nearest trailhead would be the village of San Nicolás, where the trailhead lies close to the church, the Ermita de San Nicolás.

From the airport head out northward on LP-1, which you leave at a roundabout, heading in the direction of Los Llanos along LP-2. You cross the Cumbre Nueva through the long Cumbre tunnel and reach the town of El Paso shortly after the tunnel. There turn onto LP-117 in direction Tacande. You follow this road until it rejoins LP-1 in the village of San Nicolás near its church.

Red Tape

The upper part of the lava flows with the volcano itself belongs to the Parque Natural de Cumbre Vieja, while the lower part belongs to the Monumento Natural del Tubo Volcánico de Todoque. In both preserves you are not allowed to leave the trails but there are quite a number of well kept ones so this is not really necessary. Camping also is not allowed and there are no campgrounds or "Zonas Recreativas" nearby.

When To Climb

The mountain and its surroundings can be climbed and hiked all year round. Actually due to its location on the western slopes the trail SL LP-104, which runs along to the north of San Juan is an escape route if the Ruta de los Volcanes on the Cumbre Vieja Ridge is shrouded in clouds.

Accommodation

Camping is a bit of a problem on La Palma. There are some official campgrounds in the north but the one near Los Canarios is still a project. There are, however, a couple of "Zonas Recreativas" where sometimes you are allowed to pitch a tent. None of these are in the vicinity of San Juan, unfortunately.

Other accommodations are no problem. Every European travel office will be able to book hotels, rooms and apartments for you. I won't include any links here because all of them definitely are commercial. Another option is to rent a finca (rural house) from the owners directly. You'll have to google for these but sometimes prices are low enough for the scheme to be worthwhile.

Weather Conditions

I'm a bit at a loss here. Usually all year round the Canarias have the same weather with little alterations: north-eastern trade winds which deposit fog and dew on the north-eastern slopes of the islands. The western and southern parts usually are very dry and there you'll get some hours of sunshine each day. Especially on the higher islands like La Palma you usually don't have to worry about weather too much. The mountaintops will stick out of the clouds.

Now here's my problem: when we were on our vacation to La Palma in late Febuary 2005 we had a week of fierce western winds which were loaded with moisture. We had veritable downpours for ours on end and several times couldn't even drive by car because the roads were flooded. I'm quite sure that this was a freak phenomenon. The western side of La Palma usually gets 28cm (19 inches) of rain per year!

There are no reliable weather forecasts for the mountain regions of La Palma. Often a cloudless day turns into a foggy one within half an hour. Especially the Cumbre Vieja Range is prone to these fogs and here orientation among the lava and scree fields gets very difficult. This is the main reason why you should never leave the trails there.

Forecasts for the coastal regions, however are available. You have to subtract 1°C for every 100m of altitude so that Roque de los Muchachos will still be near freezing when the coasts have already fine and sunny beach weather. The following table gives a little overview about the average weather data of the capital of Santa Cruz:

Month

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

Avg. day temp.[°C / °F]

21 / 70

21 / 70

22 / 72

22 / 72

22 / 72

24 / 75

25 / 77

26 / 79

26 / 79

26 / 79

24 / 75

22 / 72

Avg. night temp.[°C / °F]

15 / 59

14 / 57

15 / 59

16 / 61

17 / 63

18 / 64

19 / 66

21 / 70

21 / 70

19 / 66

18 / 64

16 / 61

Water temp.[°C / °F]

19 / 66

18 / 64

19 / 66

19 / 66

19 / 66

20 / 68

22 / 72

23 / 73

22 / 72

22 / 72

21 / 70

20 / 68

Sunny Hours / Day

5

6

6

7

8

9

10

9

8

6

5

5

Maps 'n' Books

Please excuse me if I only post German maps and books. I know there are editions in all European languages but I'm not aware of them. Any help is very welcome!

Maps
I have used a fantastic map by Freytag & Berndt which shows all of the many hiking and biking trails of the island. With its scale of 1:30000 it is still large enough to be useful for car tours as well. Moreover here you will find all the new designations and acronyms (which were changed some few years back).

• La Palma
  1:30000
  Edition Freytag & Berndt
  ISBN: 3-7079-0346-X

Books
The guidebook I used is every bit as good as the map with excellent tour descriptions. It is available in English as well but I am not sure about the quality of the translation.

• La Palma
  A. and W. Wolfsperger
  Rother Verlag
  ISBN:
      3-7633-4246-X (German)
      3-7633-4808-5 (English)

Images

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