Abstract: A system for near-surface geophysical subsurface imaging for detecting and characterizing subsurface heterogeneities comprises an instrument that outputs probing electromagnetic signals through a ground surface that interact and are affected by scattered signals of acoustic waves that travel through the ground surface and further senses vibrational modes of a subsurface below the ground surface; an imaging device that dynamically generates a time sequence of images of properties of the acoustic waves and maps elastic wave fields of the acoustic waves; and a processor that analyzes dynamic multi-wave data of the images to quantify spatial variations in the mechanical and viscoelastic properties of the subsurface.

Abstract: Aspects of subject technology provide systems and methods for generation and distribution of a stable identifier associated with multiple aliases of a user account. The stable identifier may be provided to various electronic devices by a server, responsive to requests associated with communications to those devices from one of the associated aliases. In this way, messaging applications can utilize the stable identifier to merge conversations from a single user having multiple aliases, and secure access to a secure device can be provided to an authorized user, even if the authorized user attempts access from an unauthorized account alias.

Abstract: A system for near-surface subsurface imaging for detecting and characterizing subsurface heterogeneities comprises a non-contact acoustic source that senses a plurality of acoustic waves that travel through a surface; an instrument that outputs probing electromagnetic signals through the surface that interact and are affected by scattered signals of the acoustic waves and further senses vibrational modes of a subsurface below the surface; an imaging device that dynamically generates a time sequence of images of properties of the acoustic waves and maps elastic wave fields of the acoustic waves; and a processor that analyzes dynamic multi-wave data of the images to quantify spatial variations in the mechanical and viscoelastic properties of the subsurface.

Abstract: A system for near-surface subsurface imaging for detecting and characterizing subsurface heterogeneities comprises a non-contact acoustic source that senses a plurality of acoustic waves that travel through a surface; an instrument that outputs probing electromagnetic signals through the surface that interact and are affected by scattered signals of the acoustic waves and further senses vibrational modes of a subsurface below the surface; an imaging device that dynamically generates a time sequence of images of properties of the acoustic waves and maps elastic wave fields of the acoustic waves; and a processor that analyzes dynamic multi-wave data of the images to quantify spatial variations in the mechanical and viscoelastic properties of the subsurface.

Abstract: A system for near-surface geophysical subsurface imaging for detecting and characterizing subsurface heterogeneities comprises an instrument that outputs probing electromagnetic signals through a ground surface that interact and are affected by scattered signals of acoustic waves that travel through the ground surface and further senses vibrational modes of a subsurface below the ground surface; an imaging device that dynamically generates a time sequence of images of properties of the acoustic waves and maps elastic wave fields of the acoustic waves; and a processor that analyzes dynamic multi-wave data of the images to quantify spatial variations in the mechanical and viscoelastic properties of the subsurface.