Global Volcanism Program | Image GVP-10162
Thick sequences of bedded phreatomagmatic tephra layers more than 100 m thick are exposed in the southern and western crater walls of Santa Ana volcano. The hydrothermally altered area at the lower right is the inner crater, which contains an acidic lake not visible in this photo. Four crater walls can be seen in this photo; the two outer walls appear on and below the center horizon, beyond the flat line that marks the rim of the 2nd crater.
Photo by Lee Siebert, 2002 (Smithsonian Institution).