The Lumberjack



Students Serving The Cal Poly Humboldt Campus and Community Since 1929

Tag: tsunamis

  • The moving pieces under Humboldt

    by Carlos Pedraza

    Cal Poly Humboldt sits on top of a very seismically active part of the world known as a the Cascadia subduction zone. This area is composed of three tectonic plates under the ocean off of the Pacific coast.

    The Juan de Fuca, Explorer, and Gorda plates are subducting beneath the continental North American Plate, where the Cal Poly Humboldt campus is located.

    As the oceanic plates push against the continental plate, the friction created leads to deformation and faulting.

    “We live on that boundary where this is taking place, which leads to frequent earthquake activity,” said Cal Poly Humboldt geology professor Amanda Admire.

    In addition to the deformation from the Cascadia subduction zone, the Humboldt region is also influenced by the movement along the San Andreas Fault to the south. Humboldt stands on top of an intersection of three different plates pushing against each other.

    The plates themselves move very slowly, only a few centimeters every year. However, they still generate friction as they move against each other. This is the energy released during an earthquake and tsunami.

    Graphic by Carlos Pedraza and August Linton

    In the Pacific Northwest, both earthquakes and tsunamis are important to prepare for. The Redwood Coast Tsunami Work Group, an organization made up of local government officials, tribes, and relief groups, gives information and warnings in their “Living on Shaking Ground”magazine.

    The magazine states that “more than two-thirds of our large historic earthquakes have been located offshore within the Gorda plate.”

    A tsunami is created when an earthquake along a fault ruptures the seafloor, moving the entire water column and releasing that built-up energy, which moves out in all directions.

    The primary local tsunami hazard, the Cascadia subduction zone, is very close to Humboldt’s coastline compared to other regions in the Pacific Northwest.

    According to Admire, a tsunami produced along the fault between the Gorda and North American plates would only take approximately ten minutes to reach the Humboldt shoreline. In Oregon and Washington the fault is further from shore, allowing for more warning time should there be a tsunami.

    This much seismic activity can be exciting to study for geologists and scientists, but for people living in Humboldt it may be nerve racking. Admire said there is no need for panic, but that residents should prepare.

    The last mega earthquake along the Cascadia subduction zone was in 1700. However, there are still smaller instances of seismic activity as the plates move and push against each other.

    So when an earthquake happens: drop, cover and hold on. If you’re near the coastline, head for higher ground in case of a tsunami.

    To find more preparedness tools and tsunami evacuation maps for the region, check out the Redwood Coast Tsunami Work Group.

  • The next great quake is coming

    The next great quake is coming

    It’s only a matter of time before nature blindsides us with a catastrophic earthquake. Geologists predict that the next big one could happen within our lifetime and we are ill-prepared for it.

    According to the Uniform California Earthquake Rupture Forecast (UCERF3), there is a 76 percent chance of an earthquake greater than a magnitude of 7.0 striking Northern California within the next the 30 years.

    We are situated along the Cascadia Subduction Zone (CSZ), a major plate boundary that stretches from Vancouver Island in Canada down to the Lost Coast in Humboldt County. It is capable of triggering “megathrusts” that can exceed 9.0 on the seismograph. Such an earthquake can set off tsunamis capable of wiping out our coastal communities. Buildings will collapse, our utilities will be cut and all hell will break loose. We need to know how to manage ourselves if and when the big one hits.

    It’s easy to forget that we live in Earthquake Country. Also, some of us are emotionally distanced from natural disasters that occur outside of our bubble, because they don’t directly affect us. Unless it hits home, we pay little mind to disasters that happen in other parts of the world. Let’s not get too comfortable, though.

    “Disaster, if we let it, can teach us that we who have not yet suffered are not untouchable; we are not special; we are lucky,” wrote Melissa Batchelor Warnke of the Los Angeles Times. “And luck runs out.”

    Living on Shaky Ground is a free magazine prepared by Humboldt Earthquake Education Center at HSU in cooperation with several relevant organizations. They offer valuable advice to prepare, protect and recover from earthquakes and tsunamis. Download and read the PDF magazine on their website today.

    Finally, we would like to remind you that the annual ShakeOut is happening on campus this Thursday, October 19 at 10:19 a.m.

    The Great California ShakeOut is an opportunity to practice how to be safer during big earthquakes. Remember to Drop, Cover and Hold On.