Richard: May 2008 Archives

The mapping group has almost completed the field work and only has to retrieve the HOBO sensors and to process the remaining data. All the panoramic photos were collected during yesterday morning's excellent weather. Noah has stitched all of them, but they still need to be resized and have their north markers added.

The final plant areas were also collected yesterday. All plant areas are marked on the map.
We need a key, but for now:  red = monoculture, yellow = mixed species, and pink/magenta = ornamental.

The springs and other water points were added using the 'hot spring' symbol. We need more symbols, and the hot spring is not too clear. I shall fix these symbols when I return to Irving.

The road data is ready to add, and we should have it up soon.

Panoramic photo has been resized and had its north marker added. This has been uploaded to the panoramic photo section of the site, as an initial test. The others should follow soon.

Another addition is the Arenal walk (zoom out to Arenal and surrounding area) - click this to see the group photo on the lava flow.

Despite dire forecasts of the tropical storm lasting until Sunday, the weather cleared early yesterday afternoon and the resulting mist lifted by about 5pm. Hence what promised to be a wash out for the mapping group actually turned out to be a productive day with a number of panoramic photos shot, and the initial experimental photos were stitched successfully. We are finding that manual exposure and auto focus are good, productive combination. Adaire has been using her artistic talents with the whiteboard images that mark the beginning of each location's photo sequence - see the photos below for some examples.

Yesterday, the mapping group also switched the HOBO temperature sensors at the springs. At the moment, they do not appear to show evidence of a hot spring but surface runoff has been a big problem. An attempt has been made to alleviate this by attempting to divert runoff to the possible hot spring, and to locate the sensors deeper. Digging in the hotspring site found two soil types. This possible mystery was solved when we looked at Spring 3 (more of a storm washout, really). The 'top soil' is a brown soil containing a lot of fine gravel/coarse sand. Under this lies the 'bed rock' - an orange clay, probably alluvial. Dr. B and myself think that soil analysis will probably make a good project for next year.

Map Updates: The main house property line has been added to the online map. The buildings have also been added, but they need photos in their pop-up windows. The Map Group has lots of data that is being processed, and should be online today/tomorrow.

Richard
(writing this on our balcony at about 6:30. I have a perfect clear view of Arenal in front of me with a little bit of steam activity from crater C. Parrots are flying around (noisy birds), and there's the general morning chatter of the rainforest below me.)

The UD Field Ecology students after walking the 1992 lava flow from Arenal.  Front row from left:  Katheryn Miller, Katherine Biernat, Noah Jouett, Lorea Ormazabal, Johanna Weston, Samantha Behrent.  Back row:  Adaire Chatry, Mary Boyum, Richard Marsden, Christopher Gurguis, Adriane Smith.

I demonstrated the use of the 'Panosaurus' panoramic head to the mapping group today, on the University of Dallas Mall. Alas we didn't have time to stitch the resulting images together, but I've just downloaded the images and stitched them. The result is very long and thin, so I've shrunk it and clipped it into two so that it fits in the blog. (we will use thumbnails next week)

MP2KMag.com have just published a 'how the sausage is made' article that I've written:

Using Virtual Earth with OpenLayers

This article concentrates on the Virtual Earth version of our maps, showing how you can use OpenLayers with Virtual Earth. The article example uses OpenLayers to add a SHP shape file layer (served by MapServer using WMS) onto the Virtual Earth base layer.

Our production maps also use OpenLayers to draw the survey grid, and to add KML layers.

The 'Website Technology' page is up. This is an initial page and lists the technologies and data sources that we have used for the site. It will be expanded over the next few weeks to give more information. It may be expanded into multiple pages if I decide to give a more in-depth discussion of specific areas. The page is here:

http://www.ecomapcostarica.com/ref/website.shtml

The descriptions for the website and this blog are only included for completeness. The panoramic photographs and online maps are more interesting.

The volcano page in the reference section is now online. The species descriptions in the same section will be written by students.

Volcan Arenal, by Jorge Barquero Hernandez (Lihssa San Jose, 2006) is the last of the volcano books that I shall be reviewing here. It is also the shortest at 50 pages, but contains the best photographs of Arenal of any of the books reviewed in this blog. It is available directly from the Arenal Volcano National Park (Parque Nacional Volcan Arenal).

The text is bilingual English/Spanish and documents Arenal's activity from 1968 to date.
The only shortcoming is that I would have preferred more text, but the photographs more than make up for this. Photographs include a rare pre-1968 photograph, as well as good coverage of the aftermath of the 1968 Vulcanian eruption, and various activity over the past 40 years. There are lots of good night-time photographs of incandescent lava and Strombolian activity. Also included are some excellent time-lapse stills of pyroclastic flows. These are amongst the best photographs that I've seen for portraying the speed and unpredictability of pyroclastic activity.

Yes a new version of the map but with a Virtual Earth base map is now online.

Virtual Earth gives much better coverage for wider Costa Rica and Central America, but does not work as well when zoomed in (ie. to the Leaves and Lizards property).

Volcanoes, by Peter Francis and Clive Oppenheimer (2nd Edition, Oxford University Press 2004) is probably the best volcano book currently in print. The late Peter Francis wrote the original first edition, which quickly became a classic when it was published in 1993. Clive Oppenheimer has done an admirable job of updating the text and covering more recent eruptions such as Soufriere Hills (Montserrat).

The target audience is definitely an educated audience, but a knowledge of geology is not necessary. Volcanology and igneous petrology both suffer from a lot of jargon, but Francis & Oppenheimer do a good job of concentrating on what is important. There are even some witticisms regarding the more obscure (but loudly argued) areas!

Coverage of Arenal is limited to a few sentences in the discussion of Vulcanian eruptions, and whether the bombs erupted in 1968 really were supersonic. Better coverage and photographs are provided for neighboring Poas which is noted for its phreatic eruptions. Despite these limitations for our study area, this book is strongly recommended for those who want a comprehensive and readable book about modern volcanology.

The initial version of the Costa Rica map is now up and online, here:

http://www.ecomapcostarica.com/map/index.shtml

If you are using a small computer screen, you may need to scroll the page down to see three "Zoom To" buttons and some notes. Select the visible layers by using the "+" button on the upper right of the map.

A version using Virtual Earth for the underlay should be uploaded in the next 2-3 days.

For those interested in the technical details, most of the map layers are being served by MapServer as WMS tiles to OpenLayer. OpenLayer adds the (KML) Leaves & Lizards layer at the client level.

Active Lavas: Monitoring and Modelling, Edited by Christopher R.J. Kilburn & Giuseppe Luoungo; UCL Press 1993
This out of print book concerns the monitoring and modeling of lava flows with the intention of improving future monitoring and the protection of civilian populations.

As such it is is probably a bit specialized for our needs. However, of interest to us is Chapter 2, The blocky andesitic lava flows of Arenal volcano, Costa Rica (pp 25-72). This takes advantage of the almost-constant effusion of Arenal's lava flows over the preceding 15-20 years to study lava flows on all scales from individual flows up to an entire volcano.

The result is a very good description of the morphology and dynamics of Arenal's lava flows. Of particular note are the field observations of which could be easily mis-interpreted by a field geologist studying an ancient lava field. For example, striations of lava flow levees could be mis-interpreted as fault slickensides. Selective erosion, truncated lava flows, and accretionary levees are also analyzed.

There are some useful lava flow descriptions which I shall be using in my volcano presentation, but otherwise this book is for a technical (field geologist) audience.

The The Volcano Adventure Guide, by Rosaly Lopes (Cambridge University Press 2005) is intended for volcano visitors who want more than what the usual tourist guides can provide. As well as an introductory section on volcanism, chapters cover safety and planning a volcano trip. Most of the book covers a range of volcanoes that are (generally) readily accessible. Volcanoes are chosen according to notoriety, things to see (eg. an eruption in progress), and accessibility.

Regions covered are: Hawai'i; Continental USA; Italy; Greece; Iceland; Costa Rica; and the West Indies.

Volcano coverage includes history, maps, places to visit, and guidelines for repose (or in the case of Arenal, "bad weather"). Lopes also adds personal accounts which range from the human (1 million people living on the slopes of Vesuvius) through to her own potentially hazardous experience on Arenal.

The technical level is aimed at the interested lay reader. Gives a good sound coverage - much better than the average tourist guide, but does not get into technical details that might swamp most readers.

This is an excellent book for someone considering a visit to a volcano or two. It can be used to choose volcanoes to visit, and also to plan your actual visit. Of course volcanoes have a tendency to change, but the book should give you enough information so that you can find out the latest status before your planned visit.

The volcano of Chaiten in Chile abruptly woke up on 2nd May. I have yet to see any official analysis, but reports and photographs suggest a Plinian eruption is in progress. Some impressive photos can be found at Times Online and other newspaper sites. The Smithsonian pages for Chaiten have yet to be updated with news, but include some useful background.
Last eruption was about 9000 years ago. Caldera with rhyolite lava dome - famed as a source of obsidian in archaeological circles.

Chaiten is a long way from Costa Rica but both are home to subduction zone volcanism. Also, Plinian eruptions are relatively rare - there have probably been about half a dozen worldwide during my lifetime - so this is of note.

Regular reports of activity at Arenal are produced by the Observatorio Vulcanologico y Sismologico de Costa Rica - Universidad Nacional (OVSICORI-UNA). English language translations are usually published by the Smithsonian Global Volcanism Program roughly every month. The latest report is typical of recent activity from the past few months:

16 April-22 April 2008

In March, activity originating from Arenal's Crater C consisted of gas emissions, sporadic Strombolian eruptions, and occasional avalanches from lava-flow fronts that traveled down the SW flanks. Volcanic activity was at relatively low levels and few eruptions occurred. Acid rain and small amounts of ejected pyroclastic material affected the NE and SE flanks. Eruptions produced ash plumes that rose about 2.2 km (7,100 ft) asl. Small avalanches of volcanic material traveled down several ravines. Crater D showed only fumarolic activity.