The relentless technology scaling calls for reduced supply voltage for dynamic power suppression. On the other hand, transistor threshold voltage cannot be scaled at the same pace to avoid excessive leakage power. Consequently, the noise margin is significantly reduced, leading to the deployment of various noise management systems that handle runtime voltage emergencies. Most of these systems rely on on-chip noise sensors, which are large in size and consume significant power. To tackle this issue, in this paper we propose a sensor-less voltage emergency estimation framework. It explores the relationship between switching activities and noise, and takes advantage of block sparse compressed sensing developed by the signal processing society. Experimental results on a few industrial designs show that by monitoring registers, voltage emergencies can be successfully predicted.