I did a little light statistics and during 1997 there were only 17 volcanos that erupted world wide, then in 1998, there wre 22 that erupted world wide. In 1999, there were 20 that erupted, and in 2000, there were over 115 eruptions world wide. This is somewha alarming. I have a feeling that mother Earth is trying to tell us something. It seems that she's getting more restless, and is keeping us awakened with all this she's doing. Is there need for concern or amy I just being paranoid? Not that any of the eruptions have come close to home, but it is causing major problems with the environment, such as air polution. With all those eruptions all year, I can see why there is concern for global warming. That's a lot of heat that is being generated. Thanks for your time and patience. (Hans Hartung)

Doing statistics on such short timescales is frought with uncertainty. I'd like to see the eruption rates - and how much lava was extruded - on longer timescales (decades and centuries) to try to make a connection between volcanoes and global warming. Man-made emissions of CO2 through fossil fuel burning seems the predominant (recent) input of greenhouse gases to the atmosphere.

Why do volcanoes become inactive? Do they ever, after being declared inactive, erupt? Is there anyway to stop a volcano from erupting? Can a volcano be inactive from the time it was formed and not ever erupt? Or is that considered a mountain and not a volcano? (I am a very curious person) (Karli Hansen, Walden III Middle School, Racine, Wisconsin)

Volcanoes become inactive as the source of magma diminishes and stops. This can occur for a number of reasons such as the movement of the plates away from the region melting, - as in the Hawaiian Islands. Deciding between a dormant and inactive volcano is difficult. You need to have information on the frequency of eruptions and when they occurred. The technique of Carbon-14 Dating is very helpful in this respect, and takes advantage of tress/plants, etc. which have been caught up and killed by eruptions - hence the radioactive "clock" starts at that time. If we know about the frequency and timing of the last eruption then maybe we can say something about the next (anticipated) eruption.

I would like to ask you how do you know if a volcano is inactive or not? Also I think your website is cool because it is interesting and I can learn a lot. (Amy Tenuta, Walden III Middle Schoool, Racine, Wisconsin)

Thanks! See the above answer.

What is a Strombolian eruption? (Mila Begun, New York City, NY USA)

Named after the Stomboli volcano in Italy, it is a type of eruptive behavior - intermittent eruption of material - the eruption column being less than 2 km in height (therefore not particularly massive).

How closely related is the activity at one volcano related to the activity of those in close proximity? (Andre, New Jersey)

Good Question - and difficult to answer. There are instances of adjacent volcanoes erupting (almost) simultaneously - for example, people know about the great Mt. Pelee eruption on Martinique in 1902 which killed 30,000 people. However, few people realize taht Soufriere on St. Vincent (about 150 KM away) erupted the day before and killed 2,000 people.

Do you find in CostaRica the variety of lava's morphologies present in Hawaii? Can you find "Hele's Hair" and "Hele's Tears", "Lava Bombs" and the tiny glass bubbles one can find around the peaks in Hawaii's active sites? (Miriam, Santa Barbara, California)

The viscosity of the lavas in Costa Rica is too great to give the characteristic Pelee's hairs and tears of Hawaii's lavas.

One of your answers tell us that predicting volcanic and seismic activity is very difficult. I know that prediction of seismic activity is (to some extent) possible by precisely measuring movement of tectonic plates, and so on. Which means do you have to predict volcanic activity and what are the limitations? Bye from Holland! (Steef de Bruijn, The Netherlands)

Some scientists are pursuing changes in the chemistry of volcanic gases as an indicator of subsurface changes in the interaction between magma and surrounding wallrock. Others are pursuing geophysical techniques. The limitations are in isolating changes in parameter under scrutiny and correlating it with volcanic eruption - a difficult proposition.

Have marine geological searches been done off the west coast of Coast Rica to indentify sources of possible water seepage into the crust, which would contribute to the volcanic steam venting? (Jim Lanier, Oregon State University)

A number of my colleagues in Scripps have been looking at gas seeps in the submarine portions of the Central American margin. Whether the vents represent volatiles associated with magma (my particular interest) or are generated in Situ through break-down reactions of sediments is an example of one type of question they are looking at.

Do you think that a volcanic explosion or group of explosions might ever cause the land mass of Costa Rica to change in such a way that the Atlantic and Pacific Oceans would merge? (Tom Green, Albuquerque, NM)

The Isthmus of Central America (the land mass joining Noth and South America) formed about 5 million years ago as sedimentary material. The closure is a consequence of plate movement as well as the availability of sufficient material. I don't think volcanoes alone would blast a route through - I think that movement of the plates is the predominant factor.

What important aspect of the study characterizes the changes in the subduction zone? (Mia Jackson, Brentwood, California)

We're looking at both the isotope characteristics of the gases of interest (carbon and helium) plus results from differences in the type and amount of subducted sediment that makes it down to the zone of magma generation, and which becomes part of the magma feeding the volcanoes.

What makes volcanic ash such fertile soil? (WG, Racine, WI)

The fertile soil is a result of the breakdown of various minerals - such as olivine, pyroxene, amphibole, and feldspar (the essential ingredients of volcanic ash and lava) which releases iron, magnesium, potassium etc to the soil.

What insight do you expect to gain in the field during
the expedition? What hypothesizes are you collecting data to test?

We're looking at the effects of changes in the subduction parameter on the gas chemistry, as well as the mass balance of various volatile species along the strike of the Central American margins.See the tabs on the home-page.