Tuesday evening, 14 October, at 10:03 p.m. Chile time, a large earthquake struck the Fourth Region, giving a severe jolt both to our mountain facilities and the La Serena compound. The epicenter was located 110 km south of La Serena, near the city of Ovalle. Depth was estimated at 30 km, and the magnitude as 6.8 on the Richter scale. The duration was over two minutes in La Serena. Strong surface waves caused Recinto residences to shake and twist, but there were no injuries and only minor damage---books falling off shelves and the like. Immediately after the shaking stopped, the "neighbor network" went into action, as residents checked on each other by telephone and door to door.
All local TV stations were put out of action, and outside telephone communications lost for several hours. Recinto electrical power was out for only twenty minutes or so, and we were able to communicate with the summit by radio and be assured that there were no significant personal injuries there. Frightened children and pets (and more than a few adults) slowly calmed down as small aftershocks rumbled by under foot.
The Tololo facilities were hit harder. Gas and water lines were ruptured in some locations, and all gas and electricity were promptly turned off until a thorough review could be conducted the next morning. The most significant potential scientific impact was the rupture of an oil pad bellows on the North bearing of the 4-m, which put the telescope out of action. Two of the three water storage tanks were damaged, severely limiting fresh water supplies. Daylight showed some damage to the 4-m prime focus access platform, to one of the dome doors, and to some of the dome-shutter bearings; otherwise the telescope buildings suffered no significant harm. The mountain road had been damaged anew by another rainstorm earlier in the week, and no travel was permitted until earthquake damage could be assessed. Fortunately there was none; meanwhile, radio communications had relieved the fears of mountain personnel regarding their families in La Serena and elsewhere. Although each item of damage on Tololo was generally not a significant impediment to operations (apart from the 4-m bellows), the overall extent of damage was worse than has been seen for at least two decades.
The oil pad bellows fittings permit the pads to accommodate themselves to slight deviations from circularity of the large RA bearings and are essential to operation. In principle they are changed by raising the entire telescope and mounting on hydraulic jacks incorporated into the structure. In practice this exercise was plagued by difficulties, beginning with jacks which did not function after twenty years sitting idle! Jorge Briones and his team (Eduardo Aguirre and Luis Pasten) merit special recognition for their extraordinary effort and ingenious improvisations, which put the telescope back in service within 48 hours of the earthquake without a minute's loss of science time---by chance, this period had been scheduled for engineering work on the drive servos. An instrument change Friday proceeded as planned, and the staff astronomers on the telescope that night noticed nothing more than the need to determine the zero point for telescope pointing. While Jorge and crew restored the 4-m to service, the rest of the mountain staff put in long hours determining the functionality of other telescopes, instruments, and systems.
Damage on Pachón was minimal; a power line break, quickly restored, and a five ton rock, which tumbled onto the road and had to be drilled, blown up, and cleared. Meanwhile, Gemini construction is moving forward rapidly. One measure of the level of activity is that lunchtime meal service for the work crews, provided in a small dormitory on Pachón, now involves three shifts for seating. Back on Tololo, the damaged water tanks are being repaired, with the water shortage remaining the most visible after-effect. However, the earthquake damage comes on the heels of major damage to the road in two particularly severe storms---one of which coincided with the need to transport over 90 truckloads of Gemini dome steel to the summit from a freighter in Coquimbo harbor. As a result, the resources of the Observatory Support Service units have been stretched to the limit for several months now.
While we suffered, fortunately, no more than inconveniences, Nature's toll on the IVth Region was much worse. Initial reports in the first few days after the earthquake failed to convey the extent of damage to small communities inland from the coast and remote from communications. Nine people were killed and more than 300 injured, mostly from collapsing adobe and stone structures. Continuing aftershocks---10 above Richter 4.5 in the following week---kept people out of surviving buildings for fear of further collapse.
Over 40,000 people, about 8% of the total population, suffered serious property damage. Over 4000 homes were destroyed by the quake, and another 6000 so severely damaged as to require demolition; 10,000 more are in need of significant repair. In many smaller communities most or all of the structures were damaged or destroyed. As I write this, in late October, travel to these communities is still difficult, heavy machinery for demolition and clearing is unavailable, stocks of emergency housing are minimal and mostly located outside of the region, and the country's capacity for building more is estimated at only 200 units a day. Some people will be without housing for many weeks. To make matters worse, a severe windstorm the day preceding the quake destroyed a large portion of the spring fruit crop in the Elqui Valley, a major income source for rural communities. Many of the hardest hit areas also expect flooding as the heavy winter snowpack in the high Andes begins to melt. This puts our loss of at most a few photons in sad perspective.
Malcolm Smith (msmith@noao.edu)