Results tagged “arenal” from EcoMap Costa Rica

I've just published all the panoramic photos, and they have been aligned (as best as is possible). Just go to the main menu and go to the panoramas page, and click on one of the thumbnails. This will display the photo comparison program which lets you fade from one year to another. You can also select different locations.

The red lines on the left and right edges mark North. I will make this more explicit in the descriptive text when I get back.

Not much other news: I've taken lots of photos for PhotoSynth, but it isn't practical to do process these until we're back (Microsoft in their wisdom wrote PhotoSynth so that it only processes when online).  Oh, and another big rock/lava fall on the north side of Arenal visible (and audible) from the cabins. Two in one week. Activity does seem to be swinging around to the north side.

This time next week, we'll probably be hiking across an old lava flow in the shadow (and earshot) of Arenal, so time to check the status:

Here is last week's entry from the Smithsonian's volcano pages:

6 May-12 May 2009

OVSICORI-UNA reported that during April activity originating from Arenal's Crater C consisted of gas emissions, sporadic Strombolian eruptions, and occasional avalanches that traveled down the SW, S, and N flanks. Acid rain and small amounts of ejected pyroclastic material affected the NE and SE flanks. Small avalanches of volcanic material traveled down several ravines. Crater D showed only fumarolic activity.

Latest report from the Smithsonian / OVSICORA-UNA:

4 June-10 June 2008

OVSICORI-UNA reported that an incandescent avalanche descended Arenal's SW flank on 6 June producing an 800-m-long scar and depositing a wide debris fan at the base of the volcano. A plume of dust, ash, and gas drifted W and NW, depositing fine ash in a small area downwind. The plume panicked tourists and park rangers 2 km away to the W. The park was immediately closed for the day and the tourists were evacuated. According to a news article, another incandescent avalanche descended the SW flank on 10 June and generated an ash plume. Authorities evacuated people in the area.

Sources: Observatorio Vulcanologico y Sismologico de Costa Rica-Universidad Nacional (OVSICORI-UNA), Nacion

Katherine, Kat, and Adriane are the members of the bird survey group. We are all biology seniors of the University of Dallas. Today, May 20, 2008, we had our first day of Field Ecology. We had our introductory overview of the course and detailed information about volcanology and Costa Rican geology. Specifics on Arenal. We were also assigned our groups and tonight we have plans to start our research. In Costa Rica we will be doing birds counts twice a day at 6am and 4pm. 

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.

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.

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.

Volcan Arenal is only a few miles away, and the study area has excellent views of the volcano when it is not shrouded in clouds.

Arenal is a active basalt-andesite stratovolcano. It is the youngest volcano in Costa Rica and has been erupting continuously since 1968. This is very unusual for an andesitic subduction zone volcano. This long lasting eruption and relatively accessible location, make Arenal one of the top locations in the world if you wish to see an active eruption in progress.

The 1968 eruption started with a Vulcanian explosion, but is now primarily Strombolian with lava flows and occasional pyroclastic flows.

Arenal is showing signs of reduced activity but continues to be very dangerous and has killed people in recent years. Do NOT climb the cone, do NOT enter closed areas, and take heed of ALL warning signs.