Final answer:
The Strombolian eruption is characterized by alternating layers of hardened cinder particles and stickier, more viscous lava, giving rise to a stratovolcano composite with periodic explosive activity.
Step-by-step explanation:
The type of volcanic eruption characterized by alternating layers of hardened particles (cinders) and the ejection of stickier, more viscous lava is known as a Strombolian eruption. These eruptions are moderate in intensity and have episodic, explosive outbursts of cindery lapilli and ash, accompanied by effusive eruptions of lava flows. The alternating layers create a stratovolcano or composite volcano with a characteristic steep profile and periodic, explosive activity.
Vulcanian eruptions are similar but are usually more violent, with larger pyroclastic fragments. Plinian eruptions, on the other hand, are characterized by continuous gas blast eruptions that eject significant quantities of pumice and ash, and can affect global climate. Phreatomagmatic eruptions are explosive due to water-magma interaction, resulting in fine ash and a wide dispersal.