Ventura Harbor NTWC Tsunami Gauge EarthCache

In October, 2014 the National Tsunami Warning Center (NTWC) installed a tsunami gauge system in Ventura Harbor.  This system utilizes a submersible pressure transducer to measure water depth, You can see the gauge standing at GZ and looking at the rocks on the southeast side of the ramp.

To claim this find, you must use the GCHQ Messenger to send me the following information:

1. The number of people in your group
2. The date and time of your visit
3. Most of the damage in the Columbian Tsunami occurred when free-rolling gangways rolled off their docks at lower-than-engineered tides. Why would that happen?
4. Abnormal flow continued for over 48 hours in 2009 and more than 72 hours in 2011. What explains the reason that would occur?
5. In 2011, the greatest fluctuation occurred 18 hours after the initial wave. What could explain that?
6. How does the daily tide influence the effect of a Tsunami Event?
7. How will the recording Tide Gauge in Ventura Harbor assist NOAA in modeling Tsunamis in the future?

The sensor is secured to the harbor bottom and provides real-time water depth measurements every 15 seconds.  The data collected is sent via the Internet to the NTWC in Palmer, Alaska, for analysis to assist in issuing tsunami warnings and cancellation notifications.  The data is also streamed to the internet for public view.

The web-site to access this data is https://tidesandcurrents.noaa.gov/tsunami/ scroll to VENTURA and hit the "WATER LEVELS" button.

For current tsunami information please visit the NTWC web page.     http://ntwc.arh.noaa.gov/

A tsunami is a traveling ocean wave generated by disturbances associated with earthquakes, volcanoes or major submarine landslides. These waves have a long wavelength (distance from the crest of one wave to the crest of the succeeding wave), normally over 100 miles, and a very low amplitude (height from crest to trough). As these waves approach shallow water, the speed decreases from a deep water speed of over 600 m.p.h. to less than 30 m.p.h., and their energy is transferred from wave speed (velocity) to wave height (amplitude); waves as high as 80-100 feet can be formed. (June 2011 Ventura County Operational Area Tsunami Evacuation Plan)

This description of a Tsunami (Tidal Wave) would lead one to believe that a Tsunami is a single wave crashing on the shore and leaving a path of destruction as far as it can reach. However, video evidence from the Boxing Day 2004 Indonesia Tsunami https://www.youtube.com/watch?v=uEhnApsywOY and the March 11, 2011 Japan earthquake https://www.youtube.com/watch?v=3pBvItnGsbA reveal the reason agencies now refer to them as a "Tsunami event."

Instead of a typical wave, the incident could better be described as the ocean temporarily receding and then rising rapidly as if a super high tide was rising in time-lapse. The ensuing current washes cars, boats, buildings and people inland. Some videos also reveal that the receding water, rushing to return to the ocean, is devastating.

The concept of "a wave" or even a "series of waves" is also a misperception. NOAA modeling of the 2011 Japan Tsunami propagation https://www.youtube.com/watch?v=PBZGH3yieLc reveals that as the Tsunami hits land masses, it bounces or refracts off the land mass. Fairly quickly, the entire Pacific Ocean becomes a washtub of refracted waves behind the leading edge of the tsunami.

Of the Harbors in Southern California, Ventura Harbor experienced the most effects from both the 2009 Colombian Tsunami and the 2011 Japan Tsunami. The Harbor Patrol observed some effects contrary to the public's typical impression of Tsunamis. Use the above information to explain these contrary observations.