Week 5- How to minimize Volcanic Hazards in the US: USGS Alert Codes

This week, at the same time everyone is following now-tropical storm Florence on the east coast, Geol9 is exploring the volcanic hazards in different countries and their warning systems. I’ll be focusing on the US.

There are several ways we minimize the danger of volcanic activity (apart from the obvious of ‘getting out of the way’…(J:

·         Forecasting (earthquakes as early warnings -although in 2014 a Japanese volcano erupted without any previous seismicity (livescience article), land swelling before eruption, gas emissions, etc.)

·         Volcanic Alert Codes (USGS): the levels of alert and the aviation code levels commonly change at the same time (chart on right). A non-erupting volcano will have a green icon, and a red one indicates an imminent eruption (see USGS Alert Codes).

Today the US hazards map shows 4 volcanoes as to be above normal background (elevated unrest):

Cleveland and Great Sitkin Alert Level=ADVISORY. Aviation Color Code=Yellow.

Kilauea and Veniaminof Alert Level=WATCH. Aviation Color Code=Orange.

Week 3-Earthquakes

This week we are exploring earthquakes and what countries do to prevent/mitigate the hazard. If I want to know something about earthquakes in a place, the first websites I go to are: the USGS Real Time Earthquakes Website or the IRIS monitoring website.

In the last month, there were 1,336 quakes of 1.5 M or larger.

Re: where quakes are located in the US, the 2014 US map of seismicity (see image below from USGS) shows the (obvious, in pink) ring of fire portion on the West coast but also a central area in the middle of the plate. I’d like to talk a bit more about this non-obvious one. This area, called the New MadridZone was shaken by a M8(!) in 1811. The reason for the activity is a very old intraplate rift placed below the area (see image from http://showme.net).

The San Andreas Fault System is responsible for most of California natural quakes...we had over 550 in the last month...up north, the Cascadia Subduction Zone will be responsible for next big one that area has. So, at least we start to know the 'why' of these quakes.

Re: the 'what to do about it', besides the obvious need for education, I want to focus on the USGS ShakeAlert system, developed for the West coast using some of the existing systems. Today, the technology exists to detect earthquakes, so quickly, that an alert can reach some areas before strong shaking arrives. The purpose of an EEW (Earthquake Early Warning) system is to identify and characterize an earthquake a few seconds after it begins, calculate the likely intensity of ground shaking that will result, and deliver warnings to people and infrastructure in harm’s way. Studies of earthquake early warning methods in California have shown that the warning time would range from a few seconds to a few tens of seconds, depending on the distance to the epicenter of the earthquake.