Stratovolcanoes sometimes have a crater at the summit that is formed by explosive ejection of material from a central vent. Sometimes the craters have been filled in by lava flows or lava domes, sometimes they are filled with glacial ice, and less commonly they are filled with water.
Podiatric management of those with peripheral vascular disease (poor circulation) should include: * A complete evaluation and assessment of the status of the circulation to the foot and communication to you about the risk that the foot is at for complications developing.
You may be wearing clothing (pants) which are too tight is some places which may also restrict blood flow to your feet. If none of these fit your situation, consult your health care provider as you may have a medical problem (high blood pressure, diabetes, old frostbite injuries) which may be contributing to decreased circulation in your feet.