Monday, October 29, 2012

Tsunami Strike! Port Angeles (not) inundated

Compared to the "perfect" storm brewing on the east coast, the 7.7 quake that hit off of the coast of Haida Gwaii this weekend has received only limited attention. The West Coast and Alaska Tsunami Warning Center issued a tsunami warning for the northern part of B.C. and some of Alaska 30 minutes after the 8:04PM earthquake. By 1009PM, the alert had been extended as a "warning" for parts of Hawaii, and then at 1044PM, the alert had been extended at an "advisory level" for parts of the California coast (see this page for a description of the 4-tier tsunami alert system). The coast of Washington in general (including the Pacific Ocean and Strait of Juan de Fuca coasts of the Olympic Peninsula) were only included in the center's alerts at a "for information only" status.

But we did get "hit"...check out these water level data from the NOAA tidal gauge in Port Angeles Harbor:

A wave train of successive ~6 inch waves every 15 minutes for close to 8 hours, starting in earnest around 11pm on Saturday. Clearly, this tsunami posed no risk to communities on the Olympic Peninsula, but such an event always gives one pause...are we ready for a worse-case scenario?

There is a clear difference between the two "types" of tsunami we can expect on the Olympic Peninsula. A "local" tsunami would be very obvious, because it would be preceded by an earthquake that would, most likely, be at least strong enough to knock us off of our feet. Our tsunami warning system for such an event is built-in...if you are knocked off your feet then, if you are able, get to high ground as soon as possible after you can stand up again. For low-lying communities, or parts of communities, the planning that needs to happen is around escape routes, knowing who and where the young and infirm are, and mobilizing resources to get everyone to safety. Distant tsunamis, which are generated far enough away that we can't feel the earthquake associated with their formation, can still be powerful enough to cause damage. For the purposes of planning for inundation, no distinction is drawn between local and distant tsunamis. we have a set of warning systems in place that are worth looking into. Many centralized communities (i.e. Port Angeles, Lower Elwha, Neah Bay, La Push)have tsunami horns in place which are plenty loud to wake everyone up in the event of a tsunami warning. For homeowners who live away from those central areas, there are a series of alternate warning sources that would be put into service in the event of a tsunami warning covering our coast:

1) The Emergency Notification System. Homes can be directly called over their landlines and notified of emergencies of any kind. This system works only with landlines.

2) As of approximately spring 2013, Clallam County will add a new system that individuals can enroll in, which will route an emergency call to any phone (including cell phones/work phones, etc.) entered into the system.

3) Clallam County uses the alert system at to notify subscribers to any community-relevant alerts. A text is sent to your mobile phone...enrolling is free and easy (it took me about one minute).

4) And finally, the old stand-by...Clallam County Sheriff personnel, fire departments, or even the Coast Guard can all be used to directly canvas communities at risk. So, in the event of a tsunami warning, you could get a knock on your door from the sherriff...

Friday, October 5, 2012

Fun with HOBOs

We use HOBOs extensively for our work in the Elwha coastal zone, and I have become a huge fan of these relatively inexpensive but robust little devices. They are inexpensive enough that when I was starting to plan for this quarter's Introduction to Oceanography class I thought that maybe, just maybe, I could figure out a way to get students using them to collect oceanographic data.

My relationship with the Feiro Marine Life Center (I am on their board) paid dividends immediately. I mentioned my desire to build oceanographic "moorings" with students in my class to the FMLC director, Deb Moriarity, and she suggested that we might be able to use a bit of funds that the FMLC and the North Olympic Peninsula Skills Center Natural Resources program (via Dan Lieberman and Tara Morrow) were granted to enhance educational opportunities in the marine sciences for local students. I had a number of local students in my course and they also wanted to create connections with colleges. Perfect! To really do it right though, I needed a few more HOBOs, and I was able to get them simply by making a request of Onset, the company that manufacturers HOBOs. They were fantastic, and quickly donated four additional sensors in support of this education project.

a student engineered mount...for temperature and light measurements on the bottom...

What do HOBOs add? With my class we've taken temperature and salinity measurements off of the P.A. Pier. That was a great exercise, especially because many of my students had never before used any sort of data collection device. We were even able to use a Van Dorn bottle to collect samples from "depth". But single samples are lacking in context - to really start to look at patterns in the ocean we need to collect data in time and space. Usually the instruments to do this are prohibitively expensive or difficult to use, but HOBOs are relatively cheap and very easy to use. So I developed an activity in which my students would build three "oceanographic moorings" with multiple HOBOs on each mooring, deploy them off of the pier, recover them and analyze the temperature and light intensity data that they log every 30 minutes.

a mid-depth sensor. The engineering challenge was to mount the HOBO such that its light sensor is always pointed up towards the sky.

The HOBOs arrived in the mail Thursday morning, and by Thursday afternoon the students from my class had built simple moorings and had them in the water. The feedback was great and students seemed to love the exercise of trying to work out how to best mount and deploy the HOBOs to maximize data quality. This was an element that I had hoped for...if my interest was only in time-series data for my students to look at I could get it off of the NANOOS or NOAA NDBC websites. But the process of building and deploying the moorings was instructive in and of itself. Students had to think about tides and currents and how they might influence their moorings. They had to think about the various sources of energy in shallow water and build a durable enough system to withstand at least a week in the water.

A gentle deployment off of the pier

So they are in the water now...check them out:

There will be more to come as we recover and analyze our data. And once more, I can't thank the FMLC, the North Olympic Peninsula Skills Center Natural Resources program and Onset enough for their contributions.

in the water...if you see them please don't take them home...