Monday, March 31, 2014

How close is too close?

More questions about working in and around volcanoes

Q: Hi I was wanting to know how close do y'all get up to a volcanic eruption.

Thank you for your time.
- Jade B

A: I have personally walked over an active moving flow southeast of Kilauea volcano in Hawai'i. However, this is an effusive flow, not an explosive one. It's pretty rough on your boots, but if you don't stay there long you will be OK. The air above the flow is very hot, however, and the discomfort usually limits our time measuring the edges (or sampling) an active flow. 

We take the dangers of volcanoes very seriously. There are people here in the Cascades Volcano Observatory who personally knew people who are now dead - killed by volcanic explosions or pyroclastic surges. We monitor the telemetered seismic, GPS, and gas data from a restive volcano closely, both to minimize risk to our scientists and to protect the public. For example, during the 2004-2006 eruption at Mount St Helens, both aircraft and hiking exclusion zones were established. The size of an exclusion zone depends on the previous eruptive history of a volcano, something not hard to get in the US, but not readily available on all world volcanoes. Most high-risk and very-high-risk volcanoes in the United States and its possessions have volcano hazard reports written for them. These include maps showing where the danger zones will likely be in case of an eruption. 

Hope this answers your question. 

Tuesday, March 25, 2014

Prediction vs. Forecasting

More detailed questions about earthquake PREDICTION and earthquake FORECASTING

Q: hello, i have looked at your website for information about predicting earthquakes and i learnt that scientists cant tell when an earthquake will exactly happen but they can assume were one will hit (the probability of a major earthquake occurring in the San Francisco Bay over the next 30 years is 67%).

i still had a question asking: what do you use (tool, machine etc) to predict earthquakes ?

i would also like to know who is answering this question.  thanks.

- Louis C

A: You are correct. After more than a century of full-time research by some of the finest minds on the planet, it is apparently not possible to PREDICT an earthquake. It IS possible, however to FORECAST an earthquake, and the example you gave is an excellent one. 

By predict, one means to know beforehand the time, location, and magnitude of an event. To forecast is to calculate the future likelihood of an event in a region that has a history of earthquake activity. In simplest terms, a geologic and instrumental record is assembled of activity in, for example the San Francisco Bay area or the Los Angeles Basin. With sufficient data, one can assemble a statistical distribution of magnitude and frequency of events. From this a forecast can be made.

The details of how this is done, that you may have already seen, can be found here:

Hope this helps answer your question.

More information on the person replying to you can be found here: 
The short version can be found here: