Living surrounded by relatively recent geologic catastrophe, I occasionally wonder, “When’s the next one?” I’m in the Basin and Range Province, where every mountain range owes its existence to faults. I’m in the Rio Grande Rift, one of the largest rift valleys in the world. We have several basaltic lava flows and cinder cones nearby, and a slew of igneous mountain ranges. The evidence of volcanism and other geologic calamities is everywhere around me… but should I worry? The faults are there. Some of the lava flows are recent. Who’s next?
Well, I don’t know. Unlike California, where earthquakes reside permanently in the backs of the minds of anyone with an inkling of geologic awareness, or near Yellowstone, which we know will explode disastrously someday, or the Cascade Mountains, with Mount Saint Helens as a constant reminder on the horizon that volcanism is not dead and might well ruin your day… in southern New Mexico I have never heard anyone worry about what our faults are doing or when there might be an eruption. I guess nothing has happened recently enough to worry us. Or the scars of past events are not quite big and spectacular enough. You might think a mile-wide crater from a maar volcano about 30 miles southwest of town might get some attention but hardly anyone in Las Cruces has even heard on Kilbourne Hole, much less visited it or worried about what such explosive potential might mean for our future. Carrizozo, at least, might have reason to be worried with a very recent lava flow just west of town. Yet, if you tried to buy volcano insurance in Carrizozo I suspect you would be met with blank stares by the local insurance agent.
All that above is kind of an excuse to show a really half-assed map:
So, those are the recentish (i.e., not yet buried under sediment) basaltic lava flows I know of in our area. Some (the Grants Malpais and Carrizozo Malpais) are very recent. Maybe we should worry, maybe we shouldn’t, I don’t know. But if I hike Tortugas Mountain on the east side of Las Cruces, I can see on a good day eight igneous mountain ranges, a few isolated cinder cones, a big basaltic lava flow, and five mountain ranges that, although comprised primarily of sedimentary rocks, owe their existence to faults. This ought, at least, to make one wonder. Even if quiescent, the evidence of disaster is around us.