Got the shakes – Chile’s March 25 earthquake from Valparaiso (150 miles north of the epicenter)

Photo by Diego Grez via Wikimedia Commons.

Sunday was kind of quiet at the hostel. I had been trying to get through with browsing all my LinkedIn notifications for the past couple days when there was some light rattling caught my attention. At first, I thought it was the return of some household pests we had been trying to get rid of for the past couple weeks, or maybe it was the dogs upstairs. Then I realized, no, this was no animal.

Whenever an earthquake hits, usually there is that fraction of a second where you try to figure out what your reaction should be. Admittedly, most of the quakes you feel here in Chile are very rapid, like a car striking the building, so by the time you decide how to react, the quake is over. This one wasn’t rapid, though.

Sunday’s 7.1-magnitude earthquake transmitted to those of us in Valparaiso the feeling of being on the actual ocean. Being centered down near Talca, about 150 miles (230 kilometers) south of here, it didn’t really feel that strong. Nothing fell off any shelf or table (the 5.1-magnitude that hit on Saturday morning did manage to send a plastic bottle to the floor in the dormitory). But there was the distinct feeling of being on board a ship as the seismic waves passed underneath the building’s foundation.

Naturally, being online, my first reaction was to find out what the scientists were saying about the strength of this quake. It used to be that you had to wait about 15 minutes for that sort of data to come up online at the USGS website. After Saturday morning’s smaller shaker, however, I discovered that the Chilean seismological service actually posts preliminary data much sooner, almost within seconds after the shaking stops. Maybe not completely accurate, but for their report you don’t have to wait.  Sure enough, they maintained this record on Sunday, posting a preliminary magnitude of 5.8 within the minute, locating it near Talca.

After the hostel dueña (owner) checked in by phone from Santiago to make sure that the place was still standing (I jokingly complained of seasickness), I went to take a shower, then returned to check out the news reports. The Chilean national television station TVN gave the surprise news that the preliminary magnitude way underestimated the size of the quake. Chile’s seismological service registered the quake as 6.8. From the United States, the USGS, apparently, had registered a 7.2-magnitude quake, again near Talca. A quick examination of the USGS shakemap on Google Earth showed that we were in a zone that felt the quake only lightly. In Regions VI and VII, Bernardo O’Higgins and Maule, the shaking was classified as “Very Strong” on the Mercali intensity scale.

Eventually, the USGS reduced its estimate to 7.1, bringing themselves closer in line to the Chilean service (usually it’s the Chileans that are considered less accurate, even by locals).

This got me thinking back to the strongest earthquake I had personally experienced. It too took place on a Sunday. While walking between buildings on the University of Alaska Fairbanks campus, I heard the sound of construction work going on within one of the tallest buildings on campus. Then I realized it was Sunday, constructors wouldn’t be at work. I looked around and saw a lamp post oscillating in a way that I had only seen in my wildest imagination. I realized we were in an earthquake only then.

There was hardly any shaking – the campus is on a very stable rock apparently, unlike out in town, where frozen soil transmitted energy without any sort of shock absorption – and after the quake was over, I turned around and went back to the student center, which was just beginning to be evacuated. Apparently the quake sounded inside as if a helicopter was landing, and a single pane of glass in the skylight had cracked. But no one was hurt, and the evacuation into the cold morning air was merely a precaution.

The magnitude of that quake was 6.9. It generated waves even thousands of miles away in a marina at New Orleans, and was considered the strongest quake of 2002 (seismically, it was a dull year). Roads were badly damaged between Anchorage and the Alaska Highway. In particular, the Parks Highway near Healy, the Richardson Highway, running parallel to the Alaska Pipeline, and the Tok Cutoff further east, were ripped apart near the fault, as the land to the south shifted meters eastward relative to the land north of the fault. It took a good couple days to reopen roads destroyed there. The Alaska Pipeline remained intact, but the pipe had shifted to nearly the end of the metal runner beam installed for it in order to keep the pipe from falling to the ground and breaking open. Above-ground diesel tanks fell, a landslide covered a glacier, as damage in the remote mountains near the hundreds of miles of transverse fault movement left people in the more populated areas amazed, and thankful that it didn’t happen where more people lived.

So far tonight, the damage report is fairly light. Other than telephone disruptions from overloaded communication links, the main damage appears to have been to the nerves of those living in regions south of Santiago. Here in Valparaiso, a couple seconds into the shaking, I had decided that I didn’t need to react. I could sit online and continue to read emails as the waves from the 7.1 magnitude quake passed northward toward their eventual dissipation distance. But it was a good reminder of the need to be prepared.

(Shortly after writing these words, the “voice of the government” for Chile, Andres Chadwick, came on CNN-Chile to tell everyone that shortly after ONEMI, the national emergency response agency, cancelled its tsunami alert, Region VII de Maule’s OREMI, the regional emergency response agency, ordered a preventive evacuation of their coast below 40 meters after seeing what appeared to be earthquake-generated waves along the coast. SHOA, the service that monitors weather and coastal waves, had not confirmed these visual sightings, but after losing a few hundred in tsunamis following the 2010 earthquake, it’s understandable that the regional authorities would be extra cautious. Additional updates: the evacuation was withdrawn at midnight. Aftershocks continue to hit the Region VII coast, though.)

The dueña on Thursday had said that some pseudo-scientist had predicted on TV a major earthquake for Friday, apparently based on solar activity. When Friday didn’t produce the 9.2 magnitude he predicted, he claimed that we were only a fraction of a degree off from facing the catastrophe forecasted. So far, we haven’t heard any “told you so” messages on the news. I’m glad for that. A real method of earthquake prediction, something more than the remarkable alert reportedly issued just before last year’s earthquake in Japan, would be a true miracle. Snake oil methods masquerading as a real prediction method being paraded on news channels, particularly as we get closer to achieving the real thing, would just make me sad.

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